LOAN AND SECURITY AGREEMENT


         This LOAN AND SECURITY  AGREEMENT is dated as of January ___, 1996, and
entered into by and between EDITEK,  INC., a Delaware  corporation,  PSYCHIATRIC
DIAGNOSTIC   LABORATORIES  OF  AMERICA,   INC.,  a  Delaware  corporation,   and
DIAGNOSTIX, INC., a Delaware corporation (collectively, "Borrowers"), with their
principal  place of business at 1238 Anthony Road,  Burlington,  North  Carolina
27215,  and HELLER  FINANCIAL,  INC., a Delaware  corporation  ("Lender"),  with
offices at 500 West Monroe Street,  Chicago,  Illinois  60661.  All  capitalized
terms used herein are defined in Section 1 of this Agreement.

         WHEREAS,  Borrowers  desire  that  Lender  extend a credit  facility to
provide  working  capital  financing  and to  provide  funds for  other  general
corporate purposes; and

         WHEREAS,  Borrowers desire to secure their  obligations  under the Loan
Documents by granting to Lender a security  interest in and lien upon certain of
Borrowers' property;

         NOW,  THEREFORE,  in  consideration of the premises and the agreements,
provisions  and  covenants  herein  contained,  Borrowers  and  Lender  agree as
follows:



                                  1 DEFINITIONS

     1.1   Certain Defined Terms. The following terms used in this Agreement 
shall have the following meanings:

         "Accounts"  means,  all  "accounts"  (as defined in the UCC),  accounts
receivable,  contract rights and general  intangibles  relating thereto,  notes,
drafts and other forms of obligations  owed to or owned by a Borrower arising or
resulting from the sale of goods or the rendering of services.

         "Affiliate"  means any Person  (other  than  Lender):  (a)  directly or
indirectly controlling, controlled by, or under common control with, a Borrower;
(b)  directly or  indirectly  owning or holding five percent (5%) or more of any
equity interest in a Borrower;  or (c) five percent (5%) or more of whose voting
stock or other  equity  interest is directly  or  indirectly  owned or held by a
Borrower. For purposes of this definition, "control" (including with correlative
meanings,  the terms  "controlling",  "controlled  by" and "under common control
with") means the  possession  directly or  indirectly  of the power to direct or
cause the direction of the management and policies of a Person,  whether through
the ownership of voting securities or by contract or otherwise.

         "Agreement"  means  this  Loan  and  Security  Agreement  as it  may be
amended, supplemented or otherwise modified from time to time.



         "Asset  Disposition"  means the  disposition,  whether by sale,  lease,
transfer, loss, damage, destruction, condemnation or otherwise, of any or all of
the  assets  of a  Borrower  or any of its  Subsidiaries  other  than  sales  of
Inventory in the ordinary course of business.

         "Availability" means, at any time of determination thereof, the Maximum
Revolving Loan Amount,  less the outstanding  principal balance of the Revolving
Loan.

         "Base  Rate" means a variable  rate of interest  per annum equal to the
higher of (a) the rate of interest  from time to time  published by the Board of
Governors of the Federal Reserve System as the "Bank Prime Loan" rate in Federal
Reserve  Statistical Release H.15(519) entitled "Selected Interest Rates" or any
successor  publication of the Federal  Reserve  System  reporting the Bank Prime
Loan rate or its  equivalent,  or (b) the  Federal  Funds  Effective  Rate.  The
statistical  release  generally  sets  forth a Bank  Prime  Loan  rate  for each
Business Day. In the event the Board of Governors of the Federal  Reserve System
ceases to publish a Bank Prime Loan rate or its equivalent, the term "Base Rate"
shall mean a variable  rate of  interest  per annum  equal to the highest of the
"prime rate",  "reference  rate",  "base rate",  or other similar rate announced
from time to time by any of Bankers Trust  Company,  The Chase  Manhattan  Bank,
National   Association  or  Chemical  Bank,  or  their   successors   (with  the
understanding  that any such  rate may  merely be a  reference  rate and may not
necessarily  represent the lowest or best rate actually  charged to any customer
by any such bank).

         "Blocked  Accounts" has the meaning assigned to that term in subsection
5.6.

         "Borrowers"  has the meaning  assigned to that term in the  preamble to
this Agreement.

         "Borrowing  Base" has the meaning  assigned to that term in  subsection
2.1(B).

         "Borrowing  Base  Certificate"   means  a  certificate  and  assignment
schedule duly executed by an officer of the  applicable  Borrower  appropriately
completed and in substantially the form of Exhibit A.

         "Business  Day" means any day  excluding  Saturday,  Sunday and any day
which is a legal holiday under the laws of the States of Minnesota,  New Jersey,
Illinois,  Pennsylvania  or  North  Carolina  or  is  a  day  on  which  banking
institutions located in any such state are closed.

         "Capital Expenditures" means all expenditures (including deposits) for,
or contracts for expenditures  (excluding  contracts for  expenditures  under or
with respect to Capital  Leases,  but  including  cash down  payments for assets
acquired under Capital Leases) with respect to any fixed assets or improvements,
or for  replacements,  substitutions or additions  thereto,  which have a useful
life of more than one year, including the direct or indirect acquisition of such
assets  by  way of  increased  product  or  service  charges,  offset  items  or
otherwise.

                                       2

         "Capital Lease" means any lease of any property (whether real, personal
or mixed) that,  in conformity  with GAAP,  should be accounted for as a capital
lease.

         "Cash  Equivalents"  means: (a) marketable direct obligations issued or
unconditionally  guarantied  by the United  States  Government  or issued by any
agency thereof and backed by the full faith and credit of the United States,  in
each case maturing  within six (6) months from the date of acquisition  thereof;
(b)  commercial  paper maturing no more than six (6) months from the date issued
and, at the time of acquisition, having a rating of at least A-1 from Standard &
Poor's Corporation or at least P-1 from Moody's Investors Service, Inc.; and (c)
certificates of deposit or bankers'  acceptances  maturing within six (6) months
from the date of issuance  thereof  issued by, or overnight  reverse  repurchase
agreements  from,  any commercial  bank  organized  under the laws of the United
States of  America or any state  thereof  or the  District  of  Columbia  having
combined  capital and surplus of not less than  $250,000,000  and not subject to
setoff rights in favor of such bank.

         "Closing  Certificate"  means a certificate  duly executed by the chief
executive  officer or chief financial  officer of Borrowers in a form reasonably
acceptable to Lender

         "Closing Date" means January ___, 1996.

         "Collateral" has the meaning assigned to that term in subsection 2.7.

         "Collecting  Banks" has the meaning assigned to that term in subsection
5.6.

         "Commitment"  or  "Commitments"  means the commitment or commitments of
Lender to make Loans as set forth in subsections 2.l(A) and 2.1(B).

         "Compliance Certificate" means a certificate duly executed by the chief
executive  officer  or  chief  financial  officer  of  Borrowers   appropriately
completed and in substantially the form of Exhibit B.

         "Default"  means a condition  or event that,  after  notice or lapse of
time or both,  would  constitute an Event of Default if that  condition or event
were not cured or removed within any applicable grace or cure period.

         "Default Rate" has the meaning assigned to that term in subsection 2.2.

                                        3

         "diAGnostix" means diAGnostix,  Inc., a Delaware  corporation,  and its
successors and permitted assigns.

         "EBITDA" means, for any period,  without duplication,  the total of the
following for  Borrowers and their  respective  Subsidiaries  on a  consolidated
basis, each calculated for such period:  (1) net income determined in accordance
with GAAP;  plus, to the extent included in the  calculation of net income,  (2)
the sum of (a)  income  and  franchise  taxes  paid  or  accrued;  (b)  Interest
Expenses,  net of interest income,  paid or accrued;  (c) interest paid in kind;
(d)  amortization  and  depreciation;  (e)  other  non-cash  charges  (excluding
accruals  for cash  expenses  made in the ordinary  course of business)  and (f)
Registration  Payments  paid or  accrued;  less,  to the extent  included in the
calculation  of net  income,  (3) the sum of (a) the income of any Person  other
than  wholly-owned  Subsidiaries  of  Borrowers  in which a Borrower or a wholly
owned  Subsidiary of a Borrower has an ownership  interest unless such income is
received by a Borrower or such wholly-owned  Subsidiary in a cash  distribution;
(b) gains or losses  from  sales or other  dispositions  of assets  (other  than
Inventory  in  the  normal  course  of  business);   and  (c)  extraordinary  or
non-recurring  gains,  but  not net of  extraordinary  or  non-recurring  "cash"
losses.

         "Editek" means EDITEK, Inc., a Delaware corporation, and its successors
and permitted assigns.

         "Eligible Accounts" has the meaning assigned to that term in subsection
2.1(B).

         "Eligible   Inventory"  has  the  meaning  assigned  to  that  term  in
subsection 2.1(B).

         "Employee  Benefit  Plan" means any  employee  benefit  plan within the
meaning of Section 3(3) of ERISA which (a) is  maintained  for  employees of any
Loan Party or any ERISA  Affiliate  or (b) has at any time within the  preceding
six (6) years been maintained for the employees of any Loan Party or any current
or former ERISA Affiliate.

         "Environmental  Claims"  means  claims,  liabilities,   investigations,
litigation,   administrative  proceedings,   judgments  or  orders  relating  to
Hazardous Materials.

         "Environmental  Laws"  means any  present or future  federal,  state or
local law, rule,  regulation or order relating to pollution,  waste, disposal or
the  protection  of human health or safety,  plant life or animal life,  natural
resources or the environment.

         "Equipment"  means all "equipment" (as defined in the UCC),  including,
without limitation, all machinery,  motor vehicles,  trucks, trailers,  vessels,
aircraft  and  rolling  stock  and  all  parts  thereof  and all  additions  and
accessions thereto and replacements therefor.

         "ERISA" means the Employee  Retirement  Income Security Act of 1974, as
amended  from  time to  time,  and any  successor  statute  and  all  rules  and
regulations promulgated thereunder.

                                       4

         "ERISA  Affiliate",  as applied to any Loan Party, means any Person who
is a member of a group which is under common  control  with any Loan Party,  who
together with any Loan Party is treated as a single  employer within the meaning
of Section 414(b) and (c) of the IRC.

         "Event of  Default"  means each of the  events set forth in  subsection
8.1.
         "Excess Cash Flow" means, for any period,  the greater of (A) zero (0);
or (B) without  duplication,  the total of the following for Borrowers and their
respective  Subsidiaries  on a  consolidated  basis,  each  calculated  for such
period:  (1) EBITDA;  plus (2) tax refunds actually  received;  less (3) Capital
Expenditures  (to the extent actually made in cash and/or due to be made in cash
within such period but in no event more than the amount  permitted by subsection
6.5 hereof);  less (4) income and franchise taxes paid or accrued  excluding any
provision for deferred taxes included in the  determination of net income;  less
(5) decreases in deferred income taxes resulting from payments of deferred taxes
accrued in prior periods;  less (6) Interest Expenses paid or accrued;  less (7)
scheduled  amortization  of  Indebtedness  actually  paid  and/or due to be paid
within  such period and  permitted  under  subsection  7.5;  less (8)  voluntary
prepayments of the Term Loans.

         "Federal Funds Effective Rate" means, for any day, the weighted average
of the rates on overnight Federal funds transactions with members of the Federal
Reserve  System  arranged  by  Federal  funds  brokers,   as  published  on  the
immediately  following  Business Day by the Federal Reserve Bank of New York or,
if  such  rate is not  published  for  any  Business  Day,  the  average  of the
quotations  for the day of the  requested  Loan  received  by Lender  from three
Federal funds brokers of recognized standing selected by Lender.

         "Fiscal  Year" means each twelve month period ending on the last day of
December in each year.

         "Fixed Charge  Coverage"  means,  for any period,  Operating  Cash Flow
divided by Fixed Charges.

         "Fixed  Charges"  means,  for any period,  and each calculated for such
period (without duplication), (a) Interest Expenses paid or accrued by Borrowers
and their respective Subsidiaries; plus (b) scheduled payments of principal with
respect to all Indebtedness of Borrowers and their respective Subsidiaries; plus
(c) any  provision  for (to the  extent  it is  greater  than  zero)  income  or
franchise  taxes  included in the  determination  of net income,  excluding  any
provision for deferred taxes;  plus (d) Restricted  Junior Payments made in cash
to the extent  permitted under subsection  7.5(b);  plus (e) payment of deferred
taxes accrued in any prior period.

         "Funding Date" means the date of each funding of a Loan.

                                             5

         "GAAP" means generally accepted accounting  principles set forth in the
opinions and  pronouncements of the Accounting  Principles Board of the American
Institute of Certified Public  Accountants and statements and  pronouncements of
the  Financial   Accounting   Standards   Board  that  are   applicable  to  the
circumstances as of the date of determination.

         "Hazardous Material" means all or any of the following:  (a) substances
that are  defined  or listed  in,  or  otherwise  classified  pursuant  to,  any
Environmental  Laws  or  regulations  as  "hazardous   substances",   "hazardous
materials",  "hazardous  wastes",  "toxic  substances" or any other  formulation
intended  to  define,  list or  classify  substances  by reason  of  deleterious
properties  such  as  ignitability,  corrosivity,  reactivity,  carcinogenicity,
reproductive toxicity or "EP toxicity";  (b) oil, petroleum or petroleum derived
substances,  natural  gas,  natural gas liquids or  synthetic  gas and  drilling
fluids,  produced  waters  and other  wastes  associated  with the  exploration,
development or production of crude oil, natural gas or geothermal resources; (c)
any flammable  substances or explosives or any  radioactive  materials;  and (d)
asbestos  in  any  form  or  electrical  equipment  which  contains  any  oil or
dielectric fluid  containing  levels of  polychlorinated  biphenyls in excess of
fifty parts per million.

         "Indebtedness",  as applied to any Person,  means without  duplication:
(a) all indebtedness  for borrowed money; (b) obligations  under leases which in
accordance  with GAAP constitute  Capital  Leases;  (c) notes payable and drafts
accepted   representing   extensions  of  credit  whether  or  not  representing
obligations for borrowed  money;  (d) any obligation owed for all or any part of
the deferred purchase price of property or services if the purchase price is due
more than six months from the date the obligation is incurred or is evidenced by
a note or similar written  instrument;  and (e) all indebtedness  secured by any
Lien on any property or asset owned or held by that Person regardless of whether
the  indebtedness  secured  thereby shall have been assumed by that Person or is
nonrecourse to the credit of that Person.

         "Intangible   Assets"  means  all  intangible  assets   (determined  in
conformity with GAAP) including, without limitation, goodwill, trademarks, trade
names,  licenses,  organizational  costs,  deferred  amounts,  covenants  not to
compete, unearned income and restricted funds.

         "Intellectual Property" means all present and future designs,  patents,
patent  rights  and  applications  therefor,  trademarks  and  registrations  or
applications therefor, trade names, inventions,  copyrights and all applications
and registrations therefor, software or computer programs, license rights, trade
secrets, methods, processes, know-how, drawings,  specifications,  descriptions,
and  all  memoranda,  notes  and  records  with  respect  to  any  research  and
development,  whether now owned or hereafter  acquired,  all goodwill associated
with any of the  foregoing,  and  proceeds of all of the  foregoing,  including,
without limitation, proceeds of insurance policies thereon.

         "Interest Coverage" means, for any period,  Operating Cash Flow divided
by Interest Expenses.

                                       6



         "Interest  Expenses" means,  without  duplication,  for any period, the
following,  for Borrowers and their respective  Subsidiaries each calculated for
such  period:  interest  expenses  deducted in the determination  of net income
(excluding  (i)  the  amortization  of  fees  and costs  with  respect  to  the
transactions  contemplated  hereunder  on  the Closing  Date  which  have  been
capitalized as transaction costs; and (ii) interest paid in kind).

         "Interest  Rate" has the meaning  assigned  to that term in  subsection
2.2(A).
         "Inventory"  means all  "inventory"  (as defined in the UCC) including,
without  limitation,  finished goods,  raw materials,  work in process and other
materials and supplies used or consumed in a Person's business,  and goods which
are returned or repossessed.

         "IRC" means the Internal  Revenue Code of 1986, as amended from time to
time,  and any  successor  statute  and all  rules and  regulations  promulgated
thereunder.

         "Lender" means Heller Financial,  Inc. together with its successors and
permitted assigns pursuant to
subsection 9.1.

         "Lender's Account" means ABA No.  0710-0001-3,  Account No. 52-98695 at
First National Bank of Chicago,  One First National  Plaza,  Chicago,  IL 60670,
Reference: Heller Business Credit for the benefit of Editek.

         "Liabilities" shall have the meaning given that term in accordance with
GAAP and shall include Indebtedness.

         "Lien" means any lien, mortgage,  pledge, security interest,  charge or
encumbrance  of any kind,  whether  voluntary  or  involuntary,  (including  any
conditional  sale or other title  retention  agreement,  any lease in the nature
thereof, and any agreement to give any security interest).

         "Loan" or  "Loans"  means an advance  or  advances  under the Term Loan
Commitment or the Revolving Loan Commitment.

         "Loan  Documents"  means this  Agreement,  the Term  Notes,  the Pledge
Agreements and all other instruments, documents and agreements executed by or on
behalf  of a  Borrower  and  delivered  concurrently  herewith  or at  any  time
hereafter to or for Lender in connection  with the Loans and other  transactions
contemplated  by this  Agreement,  all as  amended,  restated,  supplemented  or
modified from time to time.

         "Loan Party"  means,  collectively,  Borrowers,  Borrowers'  respective
Subsidiaries  and any other  Person  (other than  Lender)  which is or becomes a
party to any Loan Document.

                                      7


         "Loan  Year"  means  each  period of  twelve  (12)  consecutive  months
commencing on the Closing Date and on each anniversary thereof.

         "Material  Adverse Effect" means a material adverse effect upon (a) the
business, operations,  prospects,  properties, assets or condition (financial or
otherwise) of any Loan Party on an  individual  basis or taken as a whole or (b)
the ability of any Loan Party to perform its obligations under any Loan Document
to which it is a party or Lender to enforce or collect any of the Obligations.

         "Maximum  Revolving Loan Amount" has the meaning  assigned to that term
in subsection 2.1(B).

         "MedTox" means MedTox Laboratories,  Inc., a Minnesota corporation, and
its successors and permitted assigns.

         "MedTox  Acquisition"  means the acquisition by PDLA of the business of
MedTox occurring on or about the Closing Date.

         "MedTox  Acquisition  Agreement"  means  that  certain  Asset  Purchase
Agreement dated effective July 1, 1995, between Editek and MedTox, as amended by
that certain Amendment Agreement dated as of January 2, 1996, between Editek and
MedTox.

         "MedTox Acquisition  Documents" means the MedTox Acquisition  Agreement
and all other  documents,  agreements and  instruments  executed or delivered in
connection with the MedTox Acquisition.

         "Net Worth"  means,  as of any date,  the sum of the capital  stock and
additional paid-in capital plus retained earnings (or minus accumulated deficit)
calculated in conformity with GAAP.

         "Obligations"  means all  obligations,  liabilities and indebtedness of
every  nature of each Loan Party from time to time owed to Lender under the Loan
Documents  including the principal amount of all debts,  claims and indebtedness
(whether  incurred  before or after the  Termination  Date),  accrued and unpaid
interest and all fees, costs and expenses, whether primary,  secondary,  direct,
contingent,  fixed  or  otherwise,  heretofore,  now  and/or  from  time to time
hereafter owing, due or payable.

         "Operating  Cash Flow"  means,  for any period,  (a)  EBITDA;  less (b)
Capital Expenditures; less (c) Registration Payments paid or accrued.

         "PDLA" means Psychiatric  Diagnostic  Laboratories of America,  Inc., a
Delaware corporation, and its successors and permitted assigns.

                                        8


         "Permitted  Encumbrances" means the following types of Liens: (a) Liens
(other  than  Liens  relating  to  Environmental  Claims  or ERISA)  for  taxes,
assessments or other governmental charges not yet due and payable; (b) statutory
Liens of landlords,  carriers,  warehousemen,  mechanics,  materialmen and other
similar  liens  imposed by law,  which are  incurred in the  ordinary  course of
business  for sums not more than thirty (30) days  delinquent;  (c) Liens (other
than any Lien imposed by ERISA) incurred or deposits made in the ordinary course
of business in connection with workers' compensation, unemployment insurance and
other types of social security, statutory obligations,  surety and appeal bonds,
bids,   leases,   government   contracts,   trade  contracts,   performance  and
return-of-money  bonds and other similar  obligations  (exclusive of obligations
for the payment of borrowed money); (d) easements, rights-of-way,  restrictions,
and other  similar  charges or  encumbrances  not  interfering  in any  material
respect  with the  ordinary  conduct of the business of any Loan Party or any of
its Subsidiaries;  (e) Liens for purchase money  obligations,  provided that (i)
the purchase of the asset subject to any such Lien is permitted under subsection
6.5,  (ii)  the  Indebtedness  secured  by any  such  Lien  is  permitted  under
subsection  7.1, and (iii) such Lien encumbers only the asset so purchased;  (f)
Liens in favor of Lender, and (g) Liens set forth on Schedule 1.1(A).

         "Person"  means and includes  natural  persons,  corporations,  limited
partnerships,  general  partnerships,  limited liability companies,  joint stock
companies,  joint  ventures,  associations,   companies,  trusts,  banks,  trust
companies,  land trusts, business trusts or other organizations,  whether or not
legal entities, and governments and agencies and political subdivisions thereof.

         "Pledge  Agreements"  means the stock pledge  agreements to be executed
and  delivered by each of Editek and  Princeton in favor of Lender,  in form and
substance reasonably satisfactory to Lender.

         "PPSA" means the Personal Property  Security Act (Ontario),  as amended
from time to time.

         "Preferred  Stock" means the Series A  Convertible  Preferred  Stock of
Editek, $1.00 par value per share.

         "Princeton" means Princeton Diagnostic Laboratories of America, Inc., a
Delaware corporation, and its successors and permitted assigns.

         "Pro Forma" means the unaudited  consolidated and consolidating balance
sheet of  Borrowers  and their  respective  Subsidiaries  as of the Closing Date
after  giving  effect  to the  MedTox  Acquisition  and the  other  transactions
contemplated  by this  Agreement.  The Pro Forma is annexed  hereto as  Schedule
1.1(B).

                                            9


         "Projections"    means   Borrowers'    forecasted    consolidated   and
consolidating: (a) balance sheets; (b) profit and loss statements; (c) cash flow
statements;  and (d)  capitalization  statements,  all prepared on a division by
division and  Subsidiary  by  Subsidiary  basis and  otherwise  consistent  with
Borrowers' historical financial statements, together with appropriate supporting
details and a statement of underlying assumptions.

         "Registration Payment" means a cash payment made or required to be made
by a Borrower to a holder of Preferred Stock as a result of Editek's  failure to
register  the common stock into which such  Preferred  Stock is  convertible  or
converted,  as provided in Section 2(d) of the Registration Rights Agreements or
any successor or substitute provision.

         "Registration  Rights  Agreements"  means  those  certain  Registration
Rights  Agreements  dated on or about the  Closing  Date,  executed by Editek in
favor of the holders of the Preferred Stock.

         "Restricted   Junior  Payment"   means:   (a)  any  dividend  or  other
distribution, direct or indirect, on account of any shares of any class of stock
of a Borrower or any of its Subsidiaries now or hereafter outstanding,  except a
stock dividend;  (b) any payment or prepayment of principal of, premium, if any,
or interest on, or any redemption, conversion, exchange, retirement, defeasance,
sinking fund or similar payment, purchase or other acquisition for value, direct
or indirect,  of any Subordinated  Debt or any shares of any class of stock of a
Borrower  or any of its  Subsidiaries  now or  hereafter  outstanding;  (c)  any
payment made to retire, or to obtain the surrender of, any outstanding warrants,
options or other rights to acquire shares of any class of stock of a Borrower or
any of its  Subsidiaries  now or  hereafter  outstanding;  (d) any  payment by a
Borrower or any of its  Subsidiaries  of any management  fees or similar fees to
any Affiliate,  whether pursuant to a management agreement or otherwise; (e) any
Registration Payment; and (f) any payment of the Tax Liability.

         "Revolving  Loan"  means  all  advances  made  by  Lender  pursuant  to
subsection  2.1(B)  and  any  amounts  added  to the  principal  balance  of the
Revolving Loan pursuant to this Agreement.

         "Revolving Loan Commitment"  means the commitment of Lender to make the
Revolving Loan in the aggregate not to exceed at anytime $7,000,000.

         "Scheduled  Installment"  has the  meaning  assigned  to  that  term in
subsection 2.1(A).

         "Subsidiary"  means,  with  respect  to any  Person,  any  corporation,
association or other  business  entity of which more than fifty percent (50%) of
the  total  voting  power  of  shares  of  stock  (or  equivalent  ownership  or
controlling  interest)  entitled  (without  regard  to  the  occurrence  of  any
contingency) to vote in the election of directors,  managers or trustees thereof
is at the time owned

                                           10



or controlled,  directly or  indirectly,  by that Person or one or more of the
other subsidiaries of that Person or a combination thereof.

         "Tangible Net Worth" means an amount equal to: (a) Net Worth;  less (b)
Intangible Assets;  less (c) prepaid expenses;  less (d) all obligations owed to
such Person or any of its Subsidiaries by any Affiliate of such Person or any of
its  Subsidiaries;  and  less  (e) all  loans by such  Person  to its  officers,
stockholders or employees;  provided,  however,  that in computing  Tangible Net
Worth hereunder, up to $2,000,000 in book value of patents, trademarks and trade
names shall be deemed not to be Intangible Assets.

         "Tax  Liability"  has the  meaning  assigned to such term in the MedTox
Acquisition Agreement.

         "Term Loans" means, collectively, Term Loan A and Term Loan B.

         "Term Loan A" means the advance made pursuant to subsection 2.1(A)(1).

         "Term Loan B" means the advance made pursuant to subsection 2.1(A)(2).

         "Term Loan Commitment"  means the commitment of Lender to make the Term
Loans as set forth in this Agreement.

         "Term Note" or "Term Notes" means each  promissory note of Borrowers in
a form reasonably acceptable to Lender, issued pursuant to subsection 2.1(E).

         "Termination  Date" means the date this  Agreement is terminated as set
forth in subsection 2.5.

         "Total Loan Commitment"  means the aggregate  commitment of Lender with
respect to the Revolving Loan Commitment and the Term Loan Commitment.

         "UCC" means the Uniform Commercial Code as in effect on the date hereof
in the  State of  Illinois,  as  amended  from time to time,  and any  successor
statute.

         "Working   Capital"  means:  (a)  current  assets;   less  (b)  current
liabilities;  and less (c) the amount of any obligations  owed to such Person or
any  of  its  Subsidiaries  by  any  Affiliate  of  such  Person  or  any of its
Subsidiaries.

                                              11


             1.2  Accounting   Terms.  For  purposes  of  this  Agreement,   all
accounting terms not otherwise  defined herein shall have the meanings  assigned
to  such  terms  in  conformity  with  GAAP.   Financial  statements  and  other
information  furnished to Lender pursuant to subsection 5.1 shall be prepared in
accordance  with  GAAP  (as in  effect  at the  time of such  preparation)  on a
consistent basis. In the event any "Accounting Changes" (as defined below) shall
occur and such changes affect  financial  covenants,  standards or terms in this
Agreement,  then Borrowers and Lender agree to enter into  negotiations in order
to amend such  provisions  of this  Agreement  so as to  equitably  reflect such
Accounting  Changes with the desired result that the criteria for evaluating the
financial condition of Borrowers shall be the same after such Accounting Changes
as if such Accounting  Changes had not been made, and until such time as such an
amendment  shall have been executed and  delivered by Borrowers and Lender,  (A)
all  financial  covenants,  standards  and  terms  in this  Agreement  shall  be
calculated and/or construed as if such Accounting Changes had not been made, and
(B) Borrowers  shall prepare  footnotes to each  Compliance  Certificate and the
financial   statements   required  to  be  delivered  hereunder  that  show  the
differences  between the  financial  statements  delivered  (which  reflect such
Accounting Changes) and the basis for calculating  financial covenant compliance
(without reflecting such Accounting  Changes).  "Accounting  Changes" means: (a)
changes in accounting  principles required by GAAP and implemented by Borrowers;
(b) changes in accounting principles  recommended by Borrowers' certified public
accountants;  and (c) changes in carrying  value of  Borrowers'  or any of their
Subsidiaries'  assets,  liabilities  or equity  accounts  resulting from (i) the
application  of purchase  accounting  principles  (A.P.B.  16 and/or 17 and EITF
88-16  and FASB 109) to the  MedTox  Acquisition  or (ii) any other  adjustments
that, in each case, were applicable to, but not included in, the Pro Forma.  All
such adjustments resulting from expenditures made subsequent to the Closing Date
(including,  but not limited to, capitalization of costs and expenses or payment
of pre-Closing Date liabilities)  shall be treated as expenses in the period the
expenditures  are made and deducted as part of the calculation of EBITDA in such
period.

         1.3     Other  Definitional  Provisions.   References  to  "Sections",
"subsections",  "Exhibits" and  "Schedules"  shall be to Sections,  subsections,
Exhibits  and  Schedules,  respectively,  of  this  Agreement  unless  otherwise
specifically  provided.  Any of the terms defined in subsection 1.1 may,  unless
the context otherwise requires,  be used in the singular or the plural depending
on the  reference.  In this  Agreement,  words  importing any gender include the
other genders;  the words "including,"  "includes" and "include" shall be deemed
to be followed by the words "without  limitation";  references to agreements and
other contractual  instruments shall be deemed to include subsequent amendments,
assignments,  and  other  modifications  thereto,  but only to the  extent  such
amendments,  assignments and other modifications are not prohibited by the terms
of this  Agreement or any other Loan  Document;  references  to Persons  include
their  respective   permitted   successors  and  assigns  or,  in  the  case  of
governmental  Persons,  Persons  succeeding  to the  relevant  functions of such
Persons;  and all references to statutes and related  regulations  shall include
any amendments of same and any successor statutes and regulations.

                                    12


                             2 LOANS AND COLLATERAL

            2.1 Loans.
                  (A)(1)  Term Loan A.  Subject to the terms and  conditions  of
this  Agreement  and in reliance  upon the  representations  and  warranties  of
Borrowers  herein set forth,  Lender  agrees to lend to Borrowers on the Closing
Date Term Loan A,  which is in the  amount of  $2,000,000.  Term Loan A shall be
funded in one drawing.  Amounts  borrowed  under this  subsection  2.1(A)(1) and
repaid may not be reborrowed.  Borrowers  shall make  principal  payments in the
amounts of the applicable Scheduled  Installments of Term Loan A (or such lesser
principal  amount as shall then be  outstanding) on the dates and in the amounts
set forth below.

         "Scheduled  Installment  of Term Loan A means,  for each date set forth
below, the amount set forth opposite such date.

                  Date                               Scheduled Installment
                  ----                               ---------------------
         August 1, 1997                                      $111,111.11
         September 1, 1997                                    111,111.11
         October 1, 1997                                      111,111.11
         November 1, 1997                                     111,111.11
         December 1, 1997                                     111,111.11
         January 1, 1998                                      111,111.11
         February 1, 1998                                     111,111.11
         March 1, 1998                                        111,111.11
         April 1, 1998                                        111,111.11
         May 1, 1998                                          111,111.11
         June 1, 1998                                         111,111.11
         July 1, 1998                                         111,111.11
         August 1, 1998                                       111,111.11
         September 1, 1998                                    111,111.11
         October 1, 1998                                      111,111.11
         November 1, 1998                                     111,111.11
         December 1, 1998                                     111,111.11
         January 1, 1999                                      111,111.13

         If at any time prior to the  commencement of Scheduled  Installments of
Term Loan A set forth above, Term Loan B is fully repaid,  then on the first day
of each month,  commencing on the first day of the month following  repayment of
Term Loan B and continuing through July 1, 1997,  Borrowers shall make principal
prepayments of Term Loan A in the amount of $111,111.11  each, which prepayments
shall be applied to the Scheduled  Installments  of Term Loan A in inverse order
of maturity.
                                      13


                  (A)(2)  Term  Loan B Term  Loan B.  Subject  to the  terms and
conditions  of this  Agreement  and in  reliance  upon the  representations  and
warranties of Borrowers herein set forth,  Lender agrees to lend to Borrowers on
the Closing Date Term Loan B, which is in the amount of $2,000,000.  Term Loan B
shall be funded in one drawing. Amounts borrowed under this subsection 2.1(A)(2)
and repaid may not be reborrowed. Borrowers shall make principal payments in the
amount of the  applicable  Scheduled  Installment of Term Loan B (or such lesser
principal  amount as shall then be  outstanding) on the dates and in the amounts
set forth below

         "Scheduled  Installment of Term Loan B" means,  for each date set forth
below, the amount set forth opposite such date.

                  Date                           Scheduled Installment
                  ----                           ---------------------
         February 1, 1996                                $111,111.11
         March 1, 1996                                    111,111.11
         April 1, 1996                                    111,111.11
         May 1, 1996                                      111,111.11
         June 1, 1996                                     111,111.11
         July 1, 1996                                     111,111.11
         August 1, 1996                                   111,111.11
         September 1, 1996                                111,111.11
         October 1, 1996                                  111,111.11
         November 1, 1996                                 111,111.11
         December 1, 1996                                 111,111.11
         January 1, 1997                                  111,111.11
         February 1, 1997                                 111,111.11
         March 1, 1997                                    111,111.11
         April 1, 1997                                    111,111.11
         May 1, 1997                                      111,111.11
         June 1, 1997                                     111,111.11
         July 1, 1997                                     111,111.13

         (B)  Revolving  Loan.  Subject  to the  terms  and  conditions  of this
Agreement and in reliance upon the  representations  and warranties of Borrowers
herein  set  forth,  Lender  agrees  to lend to  Borrowers  from time to time an
aggregate  amount not to exceed at any time  $7,000,000.  Amounts borrowed under
this  subsection  2.1(B) may be repaid and  reborrowed  at any time prior to the
earlier of (i) the  termination  of the Revolving  Loan  Commitment  pursuant to
subsection 8.3 or (ii) the Termination  Date. Lender shall have no obligation to
make  advances  under this  subsection  2.1(B) to a  Borrower  to the extent the
requested advance would cause the balance of the Revolving Loan of such Borrower
then  outstanding  (after  giving  effect to any  immediate  application  of the
proceeds  thereof) to exceed the Maximum  Revolving Loan Amount of such Borrower
or to the extent any requested  advance would cause the balance of the Revolving
Loan of all  Borrowers  then

                                         14


outstanding  (after giving effect to any immediate application of the proceeds
thereof) to exceed the Revolving  Loan Commitment; provided that Lender may,
in its sole discretion, elect from time to time to make Loans in excess of the
Maximum Revolving Loan Amount of a Borrower or the Revolving Loan Commitment.
Borrowers shall maintain records of the Revolving Loan advanced to or for the
benefit of each Borrower and the amount of all repayments made by each Borrower
of such advances from proceeds of Accounts or otherwise. To the extent that the
outstanding balance of the Revolving  Loan owing by a Borrower  exceeds such
Borrower's  Borrowing Base at any time,  such excess shall be deemed to
constitute an intercompany  loan to such Borrower from another  Borrower whose
outstanding  balance of the Revolving Loan is less than its Borrower's
Borrowing Base, which intercompany loans shall be subordinate in right of
payment to the  Obligations  and shall be subject to the limitations of
subsection 7.1(b).

                  (1) "Maximum  Revolving  Loan Amount"  means,  with respect to
each Borrower, as of any date of determination,  the lesser of (a) the Revolving
Loan Commitment and (b) the Borrowing Base of such Borrower.

                  (2) "Borrowing Base" means, with respect to a Borrower,  as of
any date of determination, an amount equal to the sum of (a) eighty-five percent
(85%) of such  Borrower's  Eligible  Accounts  plus (b) the  lesser  of (i) such
Borrower's  Inventory Sublimit,  and (ii) fifty percent (50%) of such Borrower's
Eligible Inventory,  less in each case such reserves as Lender in its reasonable
discretion elects to establish.

                  (3) "Inventory  Sublimit" means,  with respect to Editek,  the
amount of  $800,000,  with  respect  to PDLA,  the amount of  $500,000  and with
respect to diAGnostix, the amount of $200,000.

          (C)   Eligible Collateral.

         "Eligible  Accounts" means, with respect to a Borrower,  as at any date
of determination, the aggregate of all Accounts of such Borrower that Lender, in
its reasonable  judgment,  deems to be eligible for borrowing purposes.  Without
limiting the generality of the foregoing, unless otherwise agreed by Lender, the
following Accounts are not Eligible Accounts:

                  (1) Accounts  which, at the date of issuance of the respective
invoice  therefor,  were  payable  more than  sixty  (60) days after the date of
issuance of such invoice;

                  (2) Accounts which remain unpaid for more than sixty (60) days
after the due date  specified  in the  original  invoice or for more than ninety
(90) days after invoice date if no due date was specified;

                  (3)  Accounts  which are  otherwise  eligible  with respect to
which the account debtor is owed a credit by a Borrower,  but only to the extent
of such credit;
                                      15

                  (4)  Accounts  due from a customer  whose  principal  place of
business is located  outside the United States of America unless such Account is
backed by a letter of credit,  in form and substance  acceptable to Lender,  and
issued or  confirmed  by a bank that is  organized  under the laws of the United
States of America or a State  thereof,  that is acceptable  to Lender,  provided
that  such  letter  of  credit  has  been  delivered  to  Lender  as  additional
collateral,  or the applicable  Borrower is the beneficiary of credit  insurance
with  respect to such account in such amounts and against such risks as shall be
acceptable to Lender;

                  (5)  Accounts  due from a customer  which  Lender has notified
Borrowers does not have a satisfactory credit standing;

                  (6) Accounts  with respect to which the customer is the United
States of America, any state or any municipality,  or any department,  agency or
instrumentality  thereof,  unless the  applicable  Borrower has, with respect to
such  Accounts,  complied  with the Federal  Assignment of Claims Act (31 U.S.C.
Section  3727) or any  applicable  statute  or  municipal  ordinance  of similar
purpose and effect;

                  (7)  Accounts  with  respect  to  which  the  customer  is  an
Affiliate of a Borrower or a director,  officer, agent,  stockholder or employee
of a Borrower or any of its Affiliates;

                  (8)  Accounts  due from a  customer  if more than  twenty-five
percent (25%) of the  aggregate  amount of Accounts of such customer have at the
time remained unpaid for more than sixty (60) days after due date or ninety (90)
days after the invoice date if no due date was specified;

                  (9)  Accounts  with  respect to which there is any  unresolved
dispute with the respective customer (but only to the extent of such dispute);

                  (10) Accounts  evidenced by an "instrument" or "chattel paper"
(as defined in the UCC) not in the possession of Lender;

                  (11)  Accounts  with  respect to which  Lender does not have a
valid, first priority and fully perfected security interest;

                  (12)  Accounts  subject to any Lien  except  those in favor of
Lender;
                  (13)  Accounts  with  respect  to which  the  customer  is the
subject of any bankruptcy or other insolvency proceeding;

                                           16


                  (14)  Accounts  due from a  customer  to the  extent  that all
Accounts of such  customer  owing to all  Borrowers  exceed in the  aggregate an
amount equal to twenty percent (20%) of the aggregate of all otherwise  Eligible
Accounts of all Borrowers at said date;

                  (15) Accounts with respect to which the customer's  obligation
to pay is conditional  or subject to a repurchase  obligation or right to return
or with respect to which the goods or services  giving rise to such Account have
not been  delivered (or performed,  as applicable)  and accepted by such account
debtor, including progress billings, bill and hold sales, guarantied sales, sale
or return transactions, sales on approval or consignment sales;

                  (16) Accounts with respect to which the customer is located in
Indiana, New Jersey,  Minnesota,  or any other state denying creditors access to
its courts in the  absence of a Notice of  Business  Activities  Report or other
similar filing, unless the applicable Borrower has either qualified as a foreign
corporation  authorized to transact business in such state or has filed a Notice
of Business Activities Report or similar filing with the applicable state agency
for the then current year;

                  (17) Accounts with respect to which the customer is a creditor
of a Borrower, provided, however, that any such Account shall only be ineligible
as to that  portion  of such  Account  which is less than or equal to the amount
owed by such Borrower to such Person.

         "Eligible Inventory" means, with respect to a Borrower,  as at any date
of  determination,  the  value  (determined  at the lower of cost or market on a
first-in,  first-out  basis) of all  Inventory  that is readily  marketable  raw
materials,  supplies in unopened  containers  or finished  goods  consisting  of
pre-packaged  test  kits,  in each case owned by and in the  possession  of such
Borrower  and located in the United  States of America and that  Lender,  in its
reasonable credit judgment, deems to be eligible for borrowing purposes. Without
limiting the generality of the foregoing, unless otherwise agreed by Lender, the
following is not Eligible Inventory: (a) work-in-process;  (b) sample collection
kits;  (c) finished goods which do not meet the  specifications  of the purchase
order for such goods; (d) Inventory which Lender determines, is unacceptable for
borrowing  purposes due to age,  quality,  type,  category and/or quantity;  (e)
Inventory with respect to which Lender does not have a valid, first priority and
fully  perfected  security  interest;  (f) Inventory with respect to which there
exists any Lien in favor of any Person other than Lender; (g) Inventory produced
in violation of the Fair Labor  Standards Act and subject to the so-called  "hot
goods"  provisions  contained in Title 29 U.S.C.  215 (a)(i);  and (h) Inventory
located at any location other than those set forth on Schedule 4.7.

                                   17


         (D) Borrowing  Mechanics.  On any day when a Borrower desires to borrow
under this subsection 2.1, Editek, acting as agent for such Borrower, shall give
Lender telephonic notice of the proposed borrowing by 11:00 a.m. (Chicago time).
Lender shall not incur any liability to Borrowers for acting upon any telephonic
notice  Lender  believes  in good faith to have been given by a duly  authorized
officer or other  person  authorized  to borrow on behalf of a  Borrower  or for
otherwise  acting in good faith under this  subsection  2.1(D).  Lender will not
make any  advance  pursuant  to any  telephonic  notice  unless  Lender has also
received the most recent  Borrowing Base  Certificates  and all other  documents
required  under  subsection  5.1(F).  Each advance made to a Borrower  under the
Revolving  Loan shall be deposited  by wire  transfer in  immediately  available
funds in such account of Editek, as agent for each Borrower,  as Editek may from
time to time  designate  to Lender in  writing,  and Editek  shall  forward  the
appropriate amount of proceeds of each such advance to or for the benefit of the
appropriate Borrower. Unless payment is otherwise timely made by a Borrower, the
becoming  due of any amount  required to be paid under this  Agreement or any of
the other Loan Documents as principal, accrued interest and fees shall be deemed
irrevocably  to be a request by such  Borrower  for a Revolving  Loan on the due
date of, and in the amount required to pay, such principal, accrued interest and
fees,  and the proceeds of each such  Revolving  Loan if made by Lender shall be
disbursed  by  Lender  by way of  direct  payment  of the  relevant  obligation.
Anything herein to the contrary notwithstanding, Lender may elect at any time to
disburse directly to each Borrower advances of the Revolving Loan that are based
upon the Borrowing Base of such Borrower.

         (E) Term Notes.  Borrowers  shall  execute and deliver to Lender a Term
Note to evidence each of the Term Loans,  such Term Notes to be in the principal
amount  of the  respective  Term  Loan  Commitment  and with  other  appropriate
insertions. In the event of an assignment under subsection 9.1, Borrowers shall,
upon surrender of the assigning  Lender's Notes,  issue new Notes to reflect the
new Commitments of the assigning Lender and its assignee.

         (F) Evidence of Revolving Loan Obligations.  The advances  constituting
the Revolving  Loan shall be evidenced by this Agreement and notations made from
time to time by Lender in its books and  records,  including  computer  records.
Lender's  books  and  records  shall  constitute  presumptive  evidence,  absent
manifest error, of the accuracy of the information contained therein. Failure by
the Lender to make any such notation or record shall not affect the  obligations
of Borrowers to Lender with respect to the Revolving Loans.

         2.2  Interest  Interest

         (A) Rate of Interest.  The Loans and all other  Obligations  shall bear
interest from the date such Loans are made or such other Obligations  become due
to the date  paid at a rate per  annum  equal  to (i) one and  one-half  percent
(1.50%) plus the Base Rate with respect to the Revolving  Loan, (ii) two percent
(2.00%)  plus the Base  Rate  with  respect  to Term  Loan A and  (iii)  two and
one-half  percent  (2.50%)  plus the Base Rate with  respect to Term Loan B (the
"Interest

                                 18


Rate"). After the occurrence and during the continuance of an Event of Default,
the Loans and all other  Obligations shall, at Lender's option,  bear interest
at a rate per annum  equal to three percent  (3.0%) plus the  Interest Rate
(the "Default Rate").

         (B) Computation and Payment of Interest.  Interest on the Loans and all
other  Obligations shall be computed on the daily principal balance on the basis
of a 360 day year for the actual  number of days  elapsed  in the period  during
which it  accrues  and shall be  payable  monthly in arrears on the first day of
each month.  Any publicly  announced  change in the Base Rate shall result in an
adjustment to the Interest  Rate on the day such change takes  effect.  Whenever
interest  payable  hereunder is  calculated  on the basis of a year of 360 days,
each rate of interest  determined  pursuant to such calculation  expressed as an
annual rate for the purpose of the Interest Act (Canada) is  equivalent  to such
rate as so  determined  multiplied by the number of days in the calendar year in
which the same is to be ascertained and divided by 360.

         (C)  Interest  Laws.  Notwithstanding  any  provision  to the  contrary
contained in this Agreement or any other Loan Document,  Borrowers  shall not be
required to pay, and Lender  shall not be  permitted  to collect,  any amount of
interest in excess of the maximum  amount of interest  permitted by law ("Excess
Interest").  If any Excess  Interest is provided for or determined by a court of
competent  jurisdiction  to have been  provided for in this  Agreement or in any
other Loan Document,  then in such event:  (1) the provisions of this subsection
shall  govern and  control;  (2) neither  Borrowers  nor any Loan Party shall be
obligated to pay any Excess  Interest;  (3) any Excess  Interest that Lender may
have received  hereunder shall be, at Lender's  option,  (a) applied as a credit
against the  outstanding  principal  balance of the  Obligations  or accrued and
unpaid  interest  (not to exceed  the  maximum  amount  permitted  by law),  (b)
refunded to the payor thereof, or (c) any combination of the foregoing;  (4) the
interest  rate(s)  provided  for herein  shall be  automatically  reduced to the
maximum lawful rate allowed from time to time under applicable law (the "Maximum
Rate"),  and this Agreement and the other Loan Documents shall be deemed to have
been and shall be,  reformed  and modified to reflect  such  reduction;  and (5)
neither  Borrowers nor any Loan Party shall have any action  against  Lender for
any damages  arising out of the payment or  collection  of any Excess  Interest.
Notwithstanding  the  foregoing,  if for  any  period  of time  interest  on any
Obligations  is calculated at the Maximum Rate rather than the  applicable  rate
under this Agreement,  and thereafter such applicable rate becomes less than the
Maximum Rate, the rate of interest payable on such  Obligations  shall remain at
the Maximum Rate until Lender shall have  received the amount of interest  which
Lender would have received  during such period on such  Obligations had the rate
of interest not been limited to the Maximum Rate during such period.

       2.3  Fees. 


         (A) Closing  Fee.  Borrowers  shall pay to Lender on the Closing Date a
closing fee in the amount of $165,000.

                                      19


         (B) Unused Line Fee.  Borrowers  shall pay to Lender a fee in an amount
equal to the Revolving Loan Commitment less the sum of the average daily balance
of the Revolving  Loan during the preceding  month  multiplied by  three-eighths
percent  (0.375) per annum,  such fee to be calculated on the basis of a 360
day year for the actual number of days elapsed and to be payable  monthly in
arrears on the first day of the first month following the Closing Date and the
first day of each month thereafter.

         (C) Prepayment Fees. If Borrowers voluntarily prepay the Obligations in
full  (other  than  voluntary  prepayments  of the  Revolving  Loan which do not
terminate the Revolving  Loan  Commitment,  including  payments of the Revolving
Loan from the Blocked Accounts),  or, in the case of any voluntary prepayment of
any Term Loan, in part, prior to the Termination Date,  Borrowers at the time of
prepayment shall pay to Lender,  as compensation for the costs of being prepared
to make funds available to Borrowers under this Agreement, and not as a penalty,
an amount determined by multiplying the percentage set forth below by (1) in the
case of a  prepayment  in full of the  Obligations,  the sum of the  outstanding
principal  balance  of the Term  Loans at the date of such  prepayment  plus the
amount of the Revolving Loan  Commitment,  or (2) in the case of a prepayment of
the Term Loans only, in whole or in part, the amount of such  prepayment:  three
percent  (3.00%)  upon a  prepayment  during the first Loan  Year;  two  percent
(2.00%) upon a prepayment  during the second Loan Year; and one percent  (1.00%)
upon a prepayment during the third Loan Year.  Borrower shall not be required to
pay  prepayment  fees  in  connection  with  any  mandatory  prepayments  of the
Obligations  pursuant to  subsection  2.4(B) or the last  sentence of subsection
2.1(A)(1).

         (D) Collateral Monitoring Fee. On the Closing Date and on the first day
of each calendar quarter thereafter,  Borrowers shall pay Lender a nonrefundable
collateral monitoring fee of $5,000; provided, however, that if as a result of a
Borrower's merging with another Borrower,  the number of Borrowers  decreases to
two or fewer,  then such  collateral  monitoring  fee shall reduce to $2,500 per
quarter  commencing  on the first day of the  calendar  quarter  following  such
merger.

         (E) Audit  Fees.  Borrowers  agree to pay  Lender an audit fee for each
inspection equal to $650 per auditor per day or any portion  thereof,  excluding
all full  days  spent  by  Lender  traveling  to or from  Borrowers'  locations,
together with  out-of-pocket  expenses,  or the  reasonable  fees,  expenses and
out-of-pocket  costs paid to third party  auditors.  Audit fees shall not exceed
$20,000 per year, plus out-of-pocket expenses, except during the existence of an
Event of Default.

         (F) Other Fees and Expenses. Borrowers shall pay to Lender, for its own
account,  all charges for returned items and all other bank charges  incurred by
Lender,  as well as  Lender's  standard  wire  transfer  charges  for each  wire
transfer made under this Agreement.

                                      20


     2.4  Payments and Prepayments.

         (A)  Manner and Time of  Payment.  In its sole  discretion,  Lender may
charge interest and other amounts  payable  hereunder to the Revolving Loan, all
as set forth on Lender's  books and records.  If Lender elects to bill Borrowers
for any amount due hereunder,  such amount shall be immediately  due and payable
with interest  thereon as provided  herein.  All payments made by Borrowers with
respect to the Obligations shall be made without deduction,  defense,  setoff or
counterclaim.  All payments to Lender hereunder shall, unless otherwise directed
by Lender,  be made in accordance  with  subsection  5.6.  Proceeds  remitted to
Lender's  Account shall be credited to the  Obligations on the day such proceeds
were received, provided, however, for the purpose of calculating interest on the
Obligations,  such funds  shall be deemed  received  on the first  Business  Day
thereafter.  Proceeds  remitted to Lender's  Account by wire  transfer  shall be
credited to the Obligations on the Business Day received; provided, however, for
the  purpose of  calculating  interest  on the  Obligations  such funds shall be
deemed received the first Business Day thereafter.

           (B) Mandatory Prepayments.

                  (1) Overadvance. At any time that the principal balance of the
Revolving Loan exceeds the Maximum Revolving Loan Amount,  Borrowers shall, upon
demand by Lender,  immediately  repay the Revolving Loan to the extent necessary
to reduce the  principal  balance to an amount that is equal to or less than the
Maximum Revolving Loan Amount.

                  (2) Proceeds of Asset Dispositions. For so long as any portion
of either Term Loan remains outstanding,  immediately upon receipt by a Borrower
or any of its  Subsidiaries  of proceeds of any Asset  Disposition  (in one or a
series  of  related  transactions),  which  proceeds  exceed  $10,000  (it being
understood that if the proceeds  exceed $10,000,  the entire amount and not just
the  portion  above  $10,000  shall be  subject to this  subsection  2.4(B)(2)),
Borrowers  shall prepay the Term Loans in an amount equal to such  proceeds.  If
Borrowers  reasonably  expect  the  proceeds  of  any  Asset  Disposition  to be
reinvested  within 180 days to repair or replace  such assets with like  assets,
Borrowers  shall  deliver the proceeds to Lender to be applied to the  Revolving
Loan,  and  Borrowers  may, so long as no Default or Event of Default shall have
occurred  and be  continuing,  reborrow  such  proceeds  only for such repair or
replacement.  If  Borrowers  fail to  reinvest  such  proceeds  within 180 days,
Borrowers  hereby  authorize  Lender to make a Revolving  Loan to repay the Term
Loans as required hereby. All such prepayments shall be applied first in payment
of Scheduled  Installments  of Term Loan B in the inverse  order of maturity and
second in payment of Scheduled  Installments of Term Loan A in the inverse order
of maturity.

                                   21


                  (3)  Prepayments  from  Excess  Cash Flow.  For so long as any
portion of either Term Loan remains  outstanding,  within ninety (90) days after
the end of each Fiscal Year,  Borrowers shall prepay the Term Loans in an amount
equal to fifty  percent  (50%) of Excess  Cash Flow for such prior  Fiscal  Year
calculated on the basis of the audited financial statements for such Fiscal Year
delivered to Lender pursuant to subsection  5.1(C).  All such  prepayments  from
Excess Cash Flow shall first be applied in payment of Scheduled  Installments of
Term Loan B until  repaid in full and then in  repayment  of Term Loan A each in
inverse  order of maturity.  Concurrently  with the making of any such  payment,
Borrowers  shall deliver to Lender a certificate of Borrowers'  chief  executive
officer or chief financial  officer  demonstrating its calculation of the amount
required to be paid.

         (C)  Voluntary  Prepayments  and  Repayments.  Except  as  provided  in
subsection 2.4(B) and except for partial prepayments from the proceeds of equity
securities  issued  by  Borrowers  on or  after  the  Closing  Date,  Borrowers'
Obligations  may only be prepaid in full and not in part.  Borrowers may, at any
time upon not less than three Business Days' prior notice to Lender,  prepay the
Term Loans or terminate the Revolving Loan Commitment;  provided,  however,  the
Revolving  Loan  Commitment  may not be terminated  by Borrowers  until the Term
Loans are paid in full.

         (D)  Payments  on  Business  Days.  Whenever  any  payment  to be  made
hereunder  shall be stated to be due on a day that is not a  Business  Day,  the
payment may be made on the next  succeeding  Business Day and such  extension of
time shall be included in the  computation of the amount of interest or fees due
hereunder.

           2.5    Term of this  Agreement.  This  Agreement  shall be  effective
until December 31, 1998 (the "Termination  Date"). The Commitments shall (unless
earlier terminated) terminate upon the earlier of (i) the occurrence of an event
specified in subsection 8.3 or (ii) the Termination  Date.  Upon  termination in
accordance with subsection 8.3 or on the Termination Date, all Obligations shall
become immediately due and payable without notice or demand. Notwithstanding any
termination,  until all Obligations  have been fully paid and satisfied,  Lender
shall be entitled to retain security interests in and liens upon all Collateral,
and even after payment of all Obligations  hereunder,  Borrowers'  obligation to
indemnify Lender in accordance with the terms hereof shall continue.

           2.6    Statements. Lender shall render a monthly statement of account
to Borrowers within twenty (20) days after the end of each month. Such statement
of account shall  constitute an account  stated  unless  Borrowers  make written
objection thereto within thirty (30) days from the date such statement is mailed
to Borrowers.  Borrowers  promise to pay all of the  Obligations as such amounts
become due or are declared due pursuant to the terms of this Agreement.

                                          22


           2.7    Grant  of  Security  Interest.   To  secure  the  payment  and
performance   of  the   Obligations,   including   all   renewals,   extensions,
restructurings and refinancings of any or all of the Obligations,  each Borrower
hereby grants to Lender a continuing security interest, lien and mortgage in and
to all right, title and interest of such Borrower in the following  property  of
such  Borrower,  whether now owned or existing or hereafter  acquired or arising
and  regardless  of where  located  (all being  collectively  referred to as the
"Collateral"):  (A) Accounts,  and all guaranties and security therefor, and all
goods and rights represented thereby or arising therefrom including the right of
stoppage  in transit,  replevin  and  reclamation;  (B)  Inventory;  (C) general
intangibles  (as defined in the UCC);  (D)  documents (as defined in the UCC) or
other receipts covering,  evidencing or representing  goods; (E) instruments (as
defined in the UCC);  (F) chattel paper (as defined in the UCC);  (G) Equipment;
(H) Intellectual  Property; (I) all deposit accounts of such Borrower maintained
with any bank or  financial  institution;  (J) all cash  and  other  monies  and
property of such  Borrower in the  possession  or under the control of Lender or
any participant;  (K) all books, records,  ledger cards, files,  correspondence,
computer programs, tapes, disks and related data processing software that at any
time evidence or contain  information  relating to any of the property described
above or are  otherwise  necessary  or  helpful  in the  collection  thereof  or
realization  thereon;  and (L) proceeds of all or any of the property  described
above,  including,  without  limitation,  the proceeds of any insurance policies
covering any of the above described property.

             2.8  Capital  Adequacy and Other  Adjustments.  In the event Lender
shall  have  determined  that the  adoption  after  the date  hereof of any law,
treaty,  governmental (or  quasi-governmental)  rule,  regulation,  guideline or
order regarding capital adequacy,  reserve  requirements or similar requirements
or compliance by Lender or any corporation  controlling  Lender with any request
or  directive  regarding  capital  adequacy,  reserve  requirements  or  similar
requirements  (whether or not having the force of law and whether or not failure
to comply  therewith  would be unlawful)  from any central bank or  governmental
agency or body having  jurisdiction  does or shall have the effect of increasing
the amount of  capital,  reserves or other funds  required to be  maintained  by
Lender or any corporation  controlling  Lender and thereby  reducing the rate of
return  on  Lender's  or such  corporation's  capital  as a  consequence  of its
obligations  hereunder,  then  Borrowers  shall from time to time within fifteen
(15) days after  notice and demand from Lender  (together  with the  certificate
referred to in the next sentence) pay to Lender additional amounts sufficient to
compensate  such Lender for such  reduction.  A certificate  as to the amount of
such cost and showing the basis of the  computation  of such cost  submitted  by
Lender to Borrowers  shall,  absent  manifest  error,  be final,  conclusive and
binding for all purposes.

         2.9      Taxes.

         (A)  No  Deductions.  Any  and  all  payments  or  reimbursements  made
hereunder  or under the Term Notes  shall be made free and clear of and  without
deduction  for  any and all  taxes,  levies,  imposts,  deductions,  charges  or
withholdings,  and all liabilities with respect thereto; excluding, however, the
following:  taxes imposed on the net income of Lender by the jurisdiction  under
the  laws of which  Lender  is  organized  or doing  business  or any  political
subdivision  thereof

                                        23



and  taxes imposed on its net income by the  jurisdiction of Lender's applicable
lending office or any political  subdivision  thereof (all such  taxes,  levies,
imposts,  deductions,  charges  or  withholdings  and  all  liabilities   with
respect  thereto  excluding  such  taxes  imposed  on  net  income,  herein "Tax
Liabilities").  If  Borrowers  shall  be  required by law to deduct any such Tax
Liabilities from or in respect of any sum payable  hereunder to Lender, then the
sum payable  hereunder  shall be increased as may be necessary so that, after
making all required deductions, Lender receives an amount equal to the sum it
would have received had no such deductions been made.

         (B) Changes in Tax Laws.  In the event that,  subsequent to the Closing
Date, (i) any changes in any existing law, regulation, treaty or directive or in
the interpretation or application thereof, (ii) any new law, regulation,  treaty
or directive  enacted or any  interpretation  or application  thereof,  or (iii)
compliance  by Lender with any request or  directive  (whether or not having the
force of law) from any governmental authority, agency or instrumentality:

                  (1)  does or  shall  subject  Lender  to any  tax of any  kind
whatsoever with respect to this Agreement, the other Loan Documents or any Loans
made  hereunder,  or  change  the basis of  taxation  of  payments  to Lender of
principal,  fees, interest or any other amount payable hereunder (except for net
income taxes,  or franchise  taxes imposed in lieu of net income taxes,  imposed
generally by federal, state or local taxing authorities with respect to interest
or commitment  or other fees payable  hereunder or changes in the rate of tax on
the overall net income of Lender); or

                  (2) does or shall  impose on Lender  any  other  condition  or
increased  cost in  connection  with the  transactions  contemplated  hereby  or
participations herein; and the result of any of the foregoing is to increase the
cost to Lender of making or continuing any Loan  hereunder,  as the case may be,
or to reduce any amount receivable hereunder,  then, in any such case, Borrowers
shall promptly pay to Lender,  upon its demand, any additional amounts necessary
to compensate Lender, on an after-tax basis, for such additional cost or reduced
amount receivable, as determined by Lender with respect to this Agreement or the
other Loan Documents. If Lender becomes entitled to claim any additional amounts
pursuant to this subsection,  it shall promptly notify Borrowers of the event by
reason  of  which  Lender  has  become  so  entitled.  A  certificate  as to any
additional  amounts  payable  pursuant to the  foregoing  sentence  submitted by
Lender to Borrowers  shall,  absent  manifest  error,  be final,  conclusive and
binding for all purposes.


                     3      CONDITIONS TO LOANS

      3.1 Conditions to Loans. The obligations of Lender to make Loans on the
Closing Date and on each Funding Date are subject to  satisfaction of all of the
conditions set forth below.

                                          24


         (A)  Closing  Deliveries.  Lender  shall  have  received,  in form  and
substance  satisfactory  to Lender,  all documents,  instruments and information
identified on Schedule  3.1(A) and all other  agreements,  notes,  certificates,
orders,  authorizations,  financing  statements,  mortgages and other  documents
which Lender may at any time reasonably request.

         (B)  Security  Interests.   Lender  shall  have  received  satisfactory
evidence that all security  interests  and liens  granted to Lender  pursuant to
this  Agreement  or the  other  Loan  Documents  have been  duly  perfected  and
constitute  first  priority liens on the  Collateral,  subject only to Permitted
Encumbrances.

         (C) Closing Date Availability.  After giving effect to the consummation
of the transactions  contemplated  hereunder on the Closing Date and the payment
by  Borrowers  of all costs,  fees and expenses  relating  thereto,  the Maximum
Revolving Loan Amount on the Closing Date shall exceed the principal  balance of
the Revolving Loans by at least $1,500,000.

         (D) Representations and Warranties.  The representations and warranties
contained  herein and in the Loan Documents shall be true,  correct and complete
in all  material  respects on and as of that  Funding Date to the same extent as
though made on and as of that date,  except for any  representation  or warranty
limited by its terms to a specific  date and taking into account any  amendments
to the Schedules or Exhibits as a result of any disclosures made by Borrowers to
Lender after the Closing Date and approved by Lender.

         (E) Fees.  With  respect  to Loans to be made or issued on the  Closing
Date,  Borrowers  shall pay the fees payable on the Closing Date  referred to in
subsection 2.3 out of the proceeds of the Loan.

         (F) No Default. No event shall have occurred and be continuing or would
result from the consummation of the requested borrowing that would constitute an
Event of Default or a Default.

         (G) Performance of Agreements.  Each Loan Party shall have performed in
all material respects all agreements and satisfied all conditions which any Loan
Document provides shall be performed by it on or before that Funding Date.

         (H) No  Prohibition.  No  order,  judgment  or  decree  of  any  court,
arbitrator or governmental  authority shall purport to enjoin or restrain Lender
from making any Loans.

         (I) No  Litigation.  There shall not be pending or, to the knowledge of
Borrowers,  threatened,  any action,  charge,  claim, demand, suit,  proceeding,
petition, governmental investigation or arbitration by, against or affecting any
Loan Party or any of its  Subsidiaries  or any property of any Loan Party or any
of its  Subsidiaries  that has not been  disclosed by Borrowers in writing,  and
there shall have  occurred no  development  in any such action,  charge,  claim,
demand,

                                       25


suit, proceeding,  petition,  governmental  investigation or arbitration that,
in the opinion of Lender,  would reasonably be expected to have a Material
Adverse Effect.

         (J) Issuance of Preferred Stock. Editek shall have issued the Preferred
Stock for an aggregate  gross purchase price of not less than  $16,000,000,  and
Editek shall have received the net cash proceeds from such issuance in an amount
not less than $15,040,000.

         (K)  MedTox  Acquisition.   The  MedTox  Acquisition  shall  have  been
consummated  on  substantially  the terms set  forth in the  MedTox  Acquisition
Documents. In connection with the MedTox Acquisition, MedTox shall have accepted
shares of Editek's  common stock in payment for not less than  $5,000,000 of the
purchase price for such acquisition.


               4 BORROWERS' REPRESENTATIONS AND WARRANTIES

       To  induce  Lender  to enter  into this  Agreement  and to make  Loans,
Borrowers represent and warrant to Lender that the following  statements are and
will be true, correct and complete:

       4.1   Organization, Powers, Capitalization.

         (A) Organization and Powers.  Each of the Loan Parties is a corporation
duly  organized,  validly  existing and in good  standing  under the laws of its
jurisdiction of  incorporation  and qualified to do business in all states where
such qualification is required except where failure to be so qualified could not
be  reasonably  expected  to have a Material  Adverse  Effect.  Each of the Loan
Parties has all requisite  corporate  power and authority to own and operate its
properties,  to  carry on its  business  as now  conducted  and  proposed  to be
conducted and to enter into each Loan Document.

         (B)  Capitalization.  The authorized  capital stock of each of the Loan
Parties is as set forth on Schedule 4.1(B). All issued and outstanding shares of
capital  stock  of each of the Loan  Parties  are duly  authorized  and  validly
issued, fully paid, nonassessable,  free and clear of all Liens other than those
in favor of Lender and such shares were issued in compliance with all applicable
state and federal laws concerning the issuance of securities.  The capital stock
of each of the Loan Parties is owned by the  stockholders and in the amounts set
forth on  Schedule  4.1(B).  No shares of the  capital  stock of any Loan Party,
other than those  described  above,  are issued and  outstanding.  Except as set
forth on Schedule 4.1(B),  there are no preemptive or other outstanding  rights,
options, warrants, conversion rights or similar agreements or understandings for
the purchase or acquisition  from any Loan Party, of any shares of capital stock
or other securities of any such entity.

                                    26


           4.2   Authorization of Borrowing, No Conflict. Each Borrower has the
corporate  power and authority to incur the  Obligations  and to grant  security
interests in the  Collateral.  On the Closing Date, the execution,  delivery and
performance of the Loan Documents by each Loan Party signatory thereto will have
been duly  authorized by all necessary  corporate and  shareholder  action.  The
execution,  delivery and performance by each Loan Party of each Loan Document to
which it is a party and the  consummation  of the  transactions  contemplated by
this Agreement and the other Loan Documents by each Loan Party do not contravene
and will not be in contravention of any applicable law, the corporate charter or
bylaws of any Loan  Party or any  agreement  or order by which any Loan Party or
any Loan  Party's  property  is bound.  This  Agreement  is,  and the other Loan
Documents,  including the Term Notes,  when executed and delivered  will be, the
legally  valid  and  binding   obligations  of  the   applicable   Loan  Parties
respectively,  each  enforceable  against the Loan Parties,  as  applicable,  in
accordance with their respective terms.

            4.3  Financial  Condition.   All  financial  statements  concerning
Borrowers and their respective Subsidiaries which have been or will hereafter be
furnished by Borrowers and their  respective  Subsidiaries to Lender pursuant to
this  Agreement  have  been  or  will  be  prepared  in  accordance   with  GAAP
consistently  applied  throughout  the  periods  involved  (except as  disclosed
therein)  and  do  or  will  present  fairly  the  financial  condition  of  the
corporations  covered  thereby as at the dates  thereof and the results of their
operations  for the periods then ended.  The Pro Forma was prepared by Borrowers
based on the unaudited  balance sheets of Borrowers dated December 31, 1995. The
Projections  delivered  and to be  delivered  have been and will be  prepared by
Borrowers in light of the past operations of the business of Borrowers and their
respective  Subsidiaries,  and such Projections represent and will represent the
good faith estimate of Borrowers and their senior management concerning the most
probable course of its business as of the date such Projections are prepared and
delivered.

            4.4  Indebtedness  and  Liabilities.  As of the  Closing  Date,  no
Borrower  nor  any of its  Subsidiaries  has  (a)  any  Indebtedness  except  as
reflected on the Pro Forma;  or (b) any  Liabilities  other than as reflected on
the Pro Forma or as incurred in the ordinary  course of business  following  the
date of the Pro Forma.

            4.5  Account Warranties.  Borrowers represent, warrant and covenant
as to each Account that,  at the time of its  creation,  the Account is a valid,
bona fide account, representing an undisputed indebtedness incurred by the named
account debtor for goods actually sold and delivered or for services  completely
rendered; there are no setoffs, offsets or counterclaims,  genuine or otherwise,
against the Account;  the Account does not represent a sale to an Affiliate or a
consignment,  sale or return or a bill and hold transaction; no agreement exists
permitting  any  deduction or discount  (other than the  discount  stated on the
invoice);  a Borrower  is the lawful  owner of the  Account and has the right to
assign the same to Lender; the Account is free of all security interests,  liens
and encumbrances other than those in favor of Lender, and the Account is due and
payable in accordance with its terms.

                                      27


             4.6  Names. Schedule  4.6  sets  forth  all  names,  trade  names,
fictitious names and business names under which each Borrower currently conducts
business or has at any time during the past five years conducted business.

             4.7  Locations; FEIN. Schedule 4.7 sets forth the location of each
Borrower's  principal place of business,  the location of each Borrower's  books
and  records,  the  location  of all  other  offices  of each  Borrower  and all
Collateral locations, and such locations are Borrowers' sole locations for their
business and the Collateral.  Each Borrower's  federal  employer  identification
number is set forth on the signature page hereof.

             4.8  Title to Properties;  Liens.  Each  Borrower  and each of its
Subsidiaries  has  good,  sufficient  and  legal  title,  subject  to  Permitted
Encumbrances,  to all its respective material properties and assets.  Except for
Permitted  Encumbrances,  all such  properties  and assets are free and clear of
Liens.  To the best  knowledge  of  Borrowers  after due  inquiry,  there are no
actual,  threatened  or  alleged  defaults  with  respect  to any leases of real
property under which any Borrower or any of its Subsidiaries is lessee or lessor
which would have a Material Adverse Effect.

             4.9  Litigation; Adverse  Facts. There are no judgments outstanding
against any Loan Party or affecting  any property of any Loan Party nor is there
any action,  charge,  claim, demand, suit,  proceeding,  petition,  governmental
investigation  or arbitration now pending or, to the best knowledge of Borrowers
after  due  inquiry,  threatened  against  or  affecting  any Loan  Party or any
property of any Loan Party which could  reasonably  be expected to result in any
Material Adverse Effect. No Loan Party has received any opinion or memorandum or
legal  advice  from  legal  counsel  to the  effect  that it is  exposed  to any
liability which could  reasonably be expected to result in any Material  Adverse
Effect.

             4.10 Payment of Taxes. All material tax returns and reports of each
Borrower and each of its  Subsidiaries  required to be filed by any of them have
been  timely  filed,  and all taxes,  assessments,  fees and other  governmental
charges upon such Persons and upon their respective  properties,  assets, income
and franchises which are shown on such returns as due and payable have been paid
when due and payable.  As of the Closing Date,  none of the United States income
tax returns of each Borrower or any of its  Subsidiaries are under audit. No tax
liens have been filed and no claims  (except as  otherwise  permitted by Section
5.9) are being  asserted with respect to any such taxes.  The charges,  accruals
and  reserves  on the books of each  Borrower  and each of its  Subsidiaries  in
respect of any taxes or other governmental charges are in accordance with GAAP.

             4.11 Performance of  Agreements.  None of the Loan Parties and none
of their respective Subsidiaries is in default in the performance, observance or
fulfillment of any of the obligations,  covenants or conditions contained in any
contractual  obligation of any such Person,  and no condition  exists that, with
the  giving  of notice or the  lapse of time or both,  would  constitute  such a
default.

                                       28


             4.12 Employee   Benefit   Plans.   Each   Borrower,   each  of  its
Subsidiaries and each ERISA Affiliate is in compliance in all material  respects
with all applicable  provisions of ERISA,  the IRC and all other applicable laws
and the  regulations  and  interpretations  thereof with respect to all Employee
Benefit Plans. No material  liability has been incurred by any Borrower,  any of
its  Subsidiaries  or any ERISA  Affiliate  which  remains  unsatisfied  for any
funding  obligation,  taxes or penalties  with  respect to any Employee  Benefit
Plan.

             4.13 Intellectual   Property.   Each   Borrower  and  each  of  its
Subsidiaries  owns,  is licensed to use or  otherwise  has the right to use, all
Intellectual  Property  used in or necessary  for the conduct of its business as
currently  conducted,  and all  such  Intellectual  Property  is  identified  on
Schedule 4.13.


             4.14  Broker's  Fees.  Except as set  forth on  Schedule  4.14,  no
broker's or finder's  fee or  commission  will be payable with respect to any of
the transactions contemplated hereby.

             4.15  Environmental  Compliance.  Each  Loan  Party has been and is
currently  in  compliance  with all  applicable  Environmental  Laws,  including
obtaining   and   maintaining   in  effect  all   permits,   licenses  or  other
authorizations  required by applicable  Environmental Laws. There are no claims,
liabilities,  investigations,  litigation,  administrative proceedings,  whether
pending  or  threatened,  or  judgments  or  orders  relating  to any  Hazardous
Materials  asserted or threatened against any Loan Party or relating to any real
property currently or formerly owned, leased or operated by any Loan Party.

             4.16 Solvency. As of and from and after the date of this Agreement,
each Borrower:  (a) owns and will own assets the fair salable value of which are
(i)  greater  than the total  amount of its  liabilities  (including  contingent
liabilities)  and (ii)  greater than the amount that will be required to pay the
probable  liabilities  of such Borrower as they mature;  (b) has capital that is
not unreasonably small in relation to its business as presently conducted or any
contemplated  or  undertaken  transaction;  and (c) does not intend to incur and
does not believe  that it will incur debts  beyond its ability to pay such debts
as they become due.  There is no material  fact known to a Borrower  that has or
could have a  Material  Adverse  Effect  and that has not been  fully  disclosed
herein or in such other  documents,  certificates  and  statements  furnished to
Lender for use in connection with the transactions contemplated hereby.

             4.17 Disclosure. No representation or warranty of Borrowers, any of
their  respective  Subsidiaries  or any  other  Loan  Party  contained  in  this
Agreement,  the financial  statements,  the other Loan  Documents,  or any other
document,  certificate or written statement  furnished to Lender by or on behalf
of any such Person for use in connection  with the Loan  Documents  contains any
untrue  statement of a material  fact or omitted,  omits or will omit to state a
material  fact  necessary in order to make the  statements  contained  herein or
therein  not  misleading  in light of the  circumstances  in which the same were
made. The  Projections  and pro forma  financial information

                                   29



contained in such materials are based upon good faith estimates and assumptions
believed by such Persons to be reasonable  at the time made,  it being
recognized by Lender that such  projections  as to  future  events  are not to
be viewed as facts and that actual results during the period or periods covered
by any such  projections may differ from the projected results.  There is no
material fact known to Borrowers that  has had or will  have a  Material Adverse
Effect  and  that has not been disclosed  herein  or in  such  other documents,
certificates  and  statements furnished to Lender for use inconnection with the
transactions  contemplated hereby.

             4.18  Insurance.   Each  Borrower  and  each  of  its  Subsidiaries
maintains adequate insurance policies for public liability,  property damage for
its business and properties,  product liability,  and business interruption,  no
notice of cancellation  has been received with respect to such policies and each
Borrower  and each of its  Subsidiaries  is in  compliance  with all  conditions
contained in such policies.

             4.19 Compliance with Laws. No Borrower nor any of its  Subsidiaries
is in  violation  of  any  law,  ordinance,  rule,  regulation,  order,  policy,
guideline  or other  requirement  of any domestic or foreign  government  or any
instrumentality or agency thereof,  having  jurisdiction over the conduct of its
business or the ownership of its properties,  including, without limitation, any
violation  relating to any use, release,  storage,  transport or disposal of any
Hazardous  Material,  which  violation  would  subject a Borrower  or any of its
Subsidiaries,  or any of their respective officers to criminal liability or have
a Material Adverse Effect and no such violation has been alleged.

             4.20 Bank  Accounts.  Schedule 4.20 sets forth the account  numbers
and locations of all bank accounts of each Borrower and its Subsidiaries.

             4.21 Subsidiaries. Borrowers have no Subsidiaries other than as set
forth on Schedule 4.21.

             4.22 Employee Matters. Except as set forth on Schedule 4.22, (a) no
Loan Party nor any of such Loan Party's  employees is subject to any  collective
bargaining  agreement,  (b) no petition for  certification  or union election is
pending  with  respect  to the  employees  of any  Loan  Party  and no  union or
collective  bargaining unit has sought such  certification  or recognition  with
respect  to the  employees  of any Loan  Party  and (c)  there  are no  strikes,
slowdowns,  work stoppages or controversies pending or, to the best knowledge of
Borrowers  after  due  inquiry,  threatened  between  any  Loan  Party  and  its
respective  employees,  other than employee  grievances  arising in the ordinary
course  of  business  which  could  reasonably  be  expected  to  have,   either
individually or in the aggregate, a Material Adverse Effect. Except as set forth
on Schedule  4.22,  no  Borrower  nor any of its  Subsidiaries  is subject to an
employment contract.

             4.23 Governmental Regulation. None of the Loan Parties is, or after
giving  effect to any loan  will be,  subject  to  regulation  under the  Public
Utility  Holding  Company Act of 1935,  the

                                       30



Federal Power Act or the  Investment Company Act of 1940 or to any federal or
state  statute or  regulation  limiting its ability to incur indebtedness for
borrowed money.

         Borrowers  may,  at any  time  and from  time to time  and  subject  to
subsection 5.13, amend any one or more of the Schedules referred in this Section
4 and any  representation or warranty  contained herein which refers to any such
Schedule  shall  from and  after  the date of any such  amendment  refer to such
Schedule as so amended, provided,  however, that in no event may Borrowers amend
any such Schedule if such amendment would reflect or evidence a Default or Event
of Default.

                         5  AFFIRMATIVE COVENANTS

         Borrowers  covenant and agree that,  so long as any of the  Commitments
hereunder  shall be in effect  and  until  payment  in full of all  Obligations,
unless Lender shall  otherwise give its prior written  consent,  Borrowers shall
perform,  and shall cause each of its Subsidiaries to perform,  all covenants in
this Section 5 applicable to such Person.

         5.1 Financial  Statements and Other  Reports.  Borrowers will maintain,
and  cause  each of their  respective  Subsidiaries  to  maintain,  a system  of
accounting  established  and  administered  in  accordance  with sound  business
practices to permit preparation of financial statements in conformity with GAAP.
Borrowers  will deliver to Lender the  financial  statements  and other  reports
described below.

                  (A) Monthly Financials.  As soon as available and in any event
within thirty (30) days after the end of each month,  Borrowers will deliver (1)
the  consolidated  and  consolidating  balance  sheet  of  Borrowers  and  their
respective Subsidiaries as at the end of such month and the related consolidated
and consolidating  statements of income,  stockholders' equity and cash flow for
such month and for the period from the beginning of the then current Fiscal Year
to the end of such month, and (2) a schedule of the outstanding Indebtedness for
borrowed  money of Borrowers  and their  respective  Subsidiaries  describing in
reasonable  detail each such debt issue or loan  outstanding  and the  principal
amount and amount of accrued and unpaid  interest with respect to each such debt
issue or loan.

                  (B)  Quarterly  Financials.  As soon as  available  and in any
event  within  forty-five  (45) days  after the end of each  quarter of a Fiscal
Year, Borrowers will deliver the consolidated and consolidating balance sheet of
Borrowers and their respective Subsidiaries as at the end of such period and the
related  consolidated  and  consolidating  statements  of income,  stockholders'
equity and cash flow for such  quarter of a Fiscal  Year and for the period from
the  beginning of the then  current  Fiscal Year to the end of such quarter of a
Fiscal Year and such financial  statements shall have been reviewed by a firm of
independent certified public accountants selected by Borrowers and acceptable to
Lender.

                                       31



                  (C) Year-End Financials. As soon as available and in any event
within  ninety  (90) days  after the end of each  Fiscal  Year,  Borrowers  will
deliver:  (1) the  consolidated  balance sheet of Borrowers and their respective
Subsidiaries as at the end of such year and the related consolidated  statements
of  income,  stockholders'  equity  and cash flow for such  Fiscal  Year;  (2) a
schedule of the  outstanding  Indebtedness  of  Borrowers  and their  respective
Subsidiaries  describing  in  reasonable  detail  each such  debt  issue or loan
outstanding  and the principal  amount and amount of accrued and unpaid interest
with  respect to each such debt issue or loan;  (3) a report with respect to the
financial  statements from a firm of independent  certified  public  accountants
selected  by  Borrowers  and  acceptable  to  Lender,   which  report  shall  be
unqualified  as to going  concern  and  scope of audit of  Borrowers  and  their
respective  Subsidiaries  and shall state that (a) such  consolidated  financial
statements  present fairly the consolidated  financial position of Borrowers and
their respective Subsidiaries as at the dates indicated and the results of their
operations  and cash flow for the  periods  indicated  in  conformity  with GAAP
applied on a basis  consistent  with prior years and (b) that the examination by
such accountants in connection with such consolidated  financial  statements has
been made in accordance  with generally  accepted  auditing  standards;  and (4)
copies  of  the  consolidating  financial  statements  of  Borrowers  and  their
respective Subsidiaries, including (a) consolidating balance sheets of Borrowers
and their  respective  Subsidiaries  as at the end of such Fiscal  Year  showing
intercompany  eliminations and (b) related consolidating  statements of earnings
of   Borrowers   and  their   respective   Subsidiaries   showing   intercompany
eliminations.

                  (D) Accountants' Certification and Reports. Together with each
delivery of consolidated  financial statements of Borrowers and their respective
Subsidiaries pursuant to subsection 5.1(C), Borrowers will deliver (1) a written
statement by its independent  certified public  accountants (a) stating that the
examination  has included a review of the terms of this Agreement as same relate
to  accounting  matters  and  (b)  stating  whether,   in  connection  with  the
examination,  any  condition or event that  constitutes a Default or an Event of
Default has come to their  attention  and, if such a condition or event has come
to their  attention,  specifying the nature and period of existence  thereof and
(2) a letter  addressed  to  Lender  from  such  accountants  stating  that such
accountants  have been informed  that a primary  intent of Borrowers was to have
the professional  services such  accountants  provided to Borrowers in preparing
their audit report and the letter referred to in this subsection  5.1(D) benefit
or influence  Lender,  and  identifying  Lenders as a party that  Borrowers have
indicated intends to rely on such professional services provided to Borrowers by
such accountants.  Promptly upon receipt thereof,  Borrowers will deliver copies
of  all  significant  reports  submitted  to  Borrowers  by  independent  public
accountants  in  connection  with each annual,  interim or special  audit of the
financial  statements  of  Borrowers  made by such  accountants,  including  the
comment letter  submitted by such  accountants to management in connection  with
their annual audit.

                  (E) Compliance Certificate. Together with the delivery of each
set of  financial  statements  referenced  in subparts  (A), (B) and (C) of this
subsection  5.1,  Borrowers  will  deliver to

                                          32


Lender a  Compliance  Certificate, together  with  copies of the  calculations
and work-up  employed to  determine Borrowers' compliance or noncompliance
with the financial covenants set forth in Section 6.

                  (F) Borrowing Base  Certificates,  Registers and Journals.  On
the Closing Date and within five (5) Business  Days after both the fifteenth and
the last day of each  month and from time to time upon the  request  of  Lender,
each Borrower shall deliver to Lender: (1) a Borrowing Base Certificate  updated
since the date of the prior Borrowing Base  Certificate,  together with a report
of the outstanding  balance of the Revolving Loan owing by such Borrower and the
amount  of all  intercompany  advances  owing  by and to such  Borrower;  (2) an
invoice  register or sales journal  describing  all sales of such Borrower since
the date of the prior invoice  register,  in form and substance  satisfactory to
Lender, and, if Lender so requests, copies of invoices evidencing such sales and
proofs of delivery relating thereto;  (3) a cash receipts journal describing all
cash  receipts  of such  Borrower  since  the date of the  prior  cash  receipts
journal; (4) an aged trial balance of all its then existing Accounts; and (5) an
aged trial balance of all its then existing accounts payable; and (6) a detailed
inventory  listing and cover summary  report.  All such reports shall be in form
and substance  satisfactory to Lender.  Notwithstanding the foregoing,  upon the
later  of July 1,  1996,  and the  first  day of the  month  following  Lender's
completion of an acceptable  field  examination of each Borrower's  reporting of
its Accounts and  Inventory,  provided that no Default or Event of Default shall
have  occurred  and be  continuing  and  provided  that  Borrowers  continuously
maintain thereafter aggregate Availability of not less than $750,000,  Borrowers
shall be required to deliver to Lender the reports set forth in this  subsection
5.1(F) only once each month,  within  five (5)  Business  Days after last day of
each month.

                  (G)  Management   Report.   Together  with  each  delivery  of
financial statements of Borrowers and their respective  Subsidiaries pursuant to
subdivisions  (A), (B) and (C) of this subsection 5.1,  Borrowers will deliver a
management  report:  (1) describing  the  operations and financial  condition of
Borrowers  and their  respective  Subsidiaries  for the month then ended and the
portion of the  current  Fiscal  Year then  elapsed (or for the Fiscal Year then
ended in the case of year-end financials); (2) setting forth in comparative form
the corresponding  figures for the corresponding  periods of the previous Fiscal
Year and the  corresponding  figures  from the most recent  Projections  for the
current Fiscal Year delivered to Lender  pursuant to 5.1(O);  and (3) discussing
the reasons  for any  significant  variations.  The  information  above shall be
presented in such detail as Lender and Borrowers shall mutually agree within two
(2) months  after the Closing Date (or in the absence of an  agreement,  in such
detail as Lender shall  reasonably  request based upon similar reports  received
from its other  asset-based  lending  borrowers)  and shall be  certified by the
chief financial officer of Borrowers to the effect that such information  fairly
presents the results of  operations  and  financial  condition of Borrowers  and
their respective Subsidiaries as at the dates and for the periods indicated.

                  (H) Appraisals. From time to time, upon the request of Lender,
Borrowers will obtain and deliver to Lender,  at Borrowers'  expense,  appraisal
reports  in form and  substance  and

                                        33


from  appraisers  satisfactory  to  Lender, stating the then  current fair
market and orderly  liquidation  values of all or any portion of the Collateral;
provided, however, so long as no Event of Default is  continuing,  Lender  shall
not  request an  appraisal  as to any  particular category  of  Collateral  to
be  performed  more  than once  every  Loan Year at Borrowers' expense.

            (I)  Government  Notices.  Borrowers  will  deliver  to Lender
promptly after receipt copies of all notices, requests, subpoenas,  inquiries or
other writings  received from any  governmental  agency  concerning any Employee
Benefit Plan, the violation or alleged violation of any Environmental  Laws, the
storage,  use or disposal of any  Hazardous  Material,  the violation or alleged
violation of the Fair Labor  Standards Act or Borrowers'  payment or non-payment
of any taxes including any tax audit.

                  (J) Events of  Default,  etc.  Promptly  upon any officer of a
Borrower  obtaining  knowledge  of any of the  following  events or  conditions,
Borrowers  shall deliver a certificate  of Borrowers'  chief  executive  officer
specifying  the nature and period of  existence  of such  condition or event and
what action  Borrowers  have taken,  are taking and propose to take with respect
thereto:  (1) any  condition  or event that  constitutes  an Event of Default or
Default; (2) any notice of default that any Person has given to Borrowers or any
of their  respective  Subsidiaries  or any other  action taken with respect to a
claimed default; or (3) any Material Adverse Effect.

                  (K)  Trade  Names.  Borrowers  and  each of  their  respective
Subsidiaries  will give Lender at least thirty (30) days advance  written notice
of any change of name or of any new trade name or fictitious business name. Each
Borrower's  use of any  trade  name  or  fictitious  business  name  will  be in
compliance with all laws regarding the use of such names.

                  (L) Locations. Borrowers will give Lender at least thirty (30)
days advance  written  notice of any change in a Borrower's  principal  place of
business  or any  change  in  the  location  of its  books  and  records  or the
Collateral or of any new location for its books and records or the Collateral.

                  (M) Bank Accounts. Borrowers will give Lender prompt notice of
any new bank accounts a Borrower or any of its Subsidiaries intends to establish
prior to its their opening same.

                  (N) Litigation. Promptly upon any officer of a Borrower or its
subsidiaries  obtaining  knowledge of (1) the  institution of any action,  suit,
proceeding,  governmental  investigation or arbitration against or affecting any
Loan  Party or any  property  of any Loan  Party  not  previously  disclosed  by
Borrowers  to  Lender  or (2) any  material  development  in any  action,  suit,
proceeding,  governmental  investigation  or  arbitration  at any  time  pending
against or  affecting  any Loan Party or any property of any Loan Party which is
reasonably  likely to have a Material  Adverse  Effect,  Borrowers will promptly
give  notice  thereof to Lender and  provide  such other  information  as may be
reasonably  available to them to enable  Lender and its counsel to evaluate such
matter.

                                              34


                  (O)  Projections.  As soon as  available  and in any  event no
later  than the last day of  Borrowers'  Fiscal  Year,  Borrowers  will  deliver
consolidated  and  consolidating  Projections of Borrowers and their  respective
Subsidiaries  through the Termination  Date, which Projections shall be month by
month for the forthcoming Fiscal Year and shall be year by year thereafter.

                  (P) Preferred Stock and Indebtedness Notices.  Borrowers shall
promptly  deliver  copies of all notices given or received by a Borrower and any
of its  Subsidiaries  with respect to  noncompliance  with any term or condition
related to the Preferred  Stock or any  Indebtedness,  and shall promptly notify
Lender of any potential or actual event of default with respect to the Preferred
Stock or any Indebtedness.

                  (Q) Other Information.  With reasonable promptness,  Borrowers
will deliver such other information and data with respect to any Loan Party, any
Subsidiary of any Loan Party or the Collateral as Lender may reasonably  request
from time to time.

                  (R) Opening  Balance  Sheet.  As soon as available  and in any
event within ninety (90) days after the Closing Date,  Borrowers will deliver an
audited consolidated and consolidating balance sheet as of the effective date of
the  MedTox  Acquisition  prepared  by a firm of  independent  certified  public
accountants reasonably acceptable to Lender.

         5.2 Access to Accountants.  Borrowers  authorize  Lender to discuss the
financial  condition and financial  statements of Borrowers and their respective
Subsidiaries  with Borrowers'  independent  public  accountants  upon reasonable
notice to Borrowers of its intention to do so, and authorizes  such  accountants
to respond to all of Lender's inquiries.

         5.3  Inspection.  Borrowers  shall  permit  Lender  and any  authorized
representatives  designated by Lender to visit and inspect any of the properties
of  Borrowers  or  any  of  its  Subsidiaries,  including  their  financial  and
accounting  records,  and to make  copies and take  extracts  therefrom,  and to
discuss their affairs, finances and business with their officers and independent
public accountants, at such reasonable times during normal business hours and as
often as may be reasonably requested.  Borrowers acknowledge that Lender intends
to make such inspections on at least a quarterly basis.

         5.4 Collateral  Records.  Borrowers  shall keep full and accurate books
and records  relating to the Collateral and shall mark such books and records to
indicate Lender's security interests in the Collateral.

         5.5 Account  Covenants;  Verification.  Borrowers  shall,  at their own
expense:  (a) cause all invoices  evidencing  Accounts and all copies thereof to
bear a notice that such  invoices are payable to the  lockboxes  established  in
accordance  with  subsection  5.6 and (b) use its best efforts to assure  prompt
payment of all amounts due or to become due under the  Accounts.  No  discounts,

                                          35


credits or  allowances  will be  issued,  granted  or  allowed  with  respect to
Accounts by  Borrowers  to  customers  and no returns  will be accepted  without
Lender's prior written consent;  provided,  that until Lender notifies Borrowers
to the  contrary,  Borrowers may presume  consent.  Borrowers  will  immediately
notify  Lender in the event that a customer  alleges  any  dispute or claim with
respect to an Account or of any other  circumstances known to Borrowers that may
impair the  validity  or  collectibility  of an Account.  Lender  shall have the
right,  at any time or times  hereafter,  to verify the validity,  amount or any
other matter relating to an Account, by mail,  telephone or in person. After the
occurrence of a Default or an Event of Default, Borrowers shall not, without the
prior consent of Lender,  adjust,  settle or compromise the amount or payment of
any Account,  or release  wholly or partly any customer or obligor  thereof,  or
allow any credit or discount thereon.

         5.6 Collection of Accounts and Payments.  Each Borrower shall establish
lockboxes  and  blocked  accounts  (collectively,  "Blocked  Accounts")  in such
Borrower's name with such banks ("Collecting Banks") as are acceptable to Lender
(subject to irrevocable  instructions  acceptable to Lender as  hereinafter  set
forth) to which all account  debtors of such Borrower  shall  directly remit all
payments on Accounts and in which such  Borrower  will  immediately  deposit all
payments  made  for  Inventory  or  other  payments   constituting  proceeds  of
Collateral in the identical form in which such payment was made, whether by cash
or  check.  The  Collecting  Banks  shall  acknowledge  and  agree,  in a manner
satisfactory to Lender,  that all payments made to the Blocked  Accounts are the
sole and exclusive  property of Lender,  and that the  Collecting  Banks have no
right of setoff against the Blocked Accounts and that all such payments received
will be promptly  transferred to Lender's  Account.  Borrowers hereby agree that
all payments  received by Lender,  whether by cash,  check, wire transfer or any
other instrument,  made to such Blocked Accounts or otherwise received by Lender
and whether on the Accounts or as proceeds of other Collateral or otherwise will
be the sole and exclusive  property of Lender.  The  applicable  Borrower  shall
irrevocably  instruct each Collecting Bank to promptly  transfer all payments or
deposits to the Blocked Accounts into Lender's Account.  Each Borrower,  and any
of its Affiliates,  employees,  agents or other Persons acting for or in concert
with a Borrower,  shall, acting as trustee for Lender,  receive, as the sole and
exclusive property of Lender,  any monies,  checks,  notes,  drafts or any other
payments  relating to and/or proceeds of Accounts or other Collateral which come
into the  possession  or under the control of a Borrower or any of a  Borrower's
Affiliates,  employees,  agents or other Persons acting for or in concert with a
Borrower, and immediately upon receipt thereof,  Borrowers or such Persons shall
remit  the  same or cause  the same to be  remitted,  in  kind,  to the  Blocked
Accounts or to Lender at its address set forth in subsection 9.6 below.

         5.7 Endorsement.  Each Borrower hereby  constitutes and appoints Lender
and all Persons  designated by Lender for that purpose as such  Borrower's  true
and lawful  attorney-in-fact,  with power to endorse such Borrower's name to any
of the items of payment or proceeds  described in  subsection  5.6 above and all
proceeds of  Collateral  that come into Lender's  possession  or under  Lender's
control. Both the appointment of Lender as each Borrower's attorney and Lender's
rights and powers are coupled with an interest and are irrevocable until payment
in full and complete performance of all of the Obligations.

                                           36


         5.8 Corporate Existence. Each Borrower will, and will cause each of its
Subsidiaries  to, at all times  preserve  and keep in full  force and effect its
corporate  existence  and all rights and  franchises  material to its  business.
Borrowers  will  promptly  notify  Lender of any change in a  Borrower's  or its
Subsidiaries' ownership or corporate structure.

         5.9  Payment  of Taxes.  Borrowers  will,  and will cause each of their
respective  Subsidiaries to, pay all taxes,  assessments and other  governmental
charges  imposed upon it or any of its  properties  or assets or with respect to
any of its franchises,  business,  income or property before any penalty accrues
thereon  provided  that no such  tax  need be paid if a  Borrower  or one of its
Subsidiaries  is  contesting  same  in good  faith  by  appropriate  proceedings
promptly  instituted  and  diligently  conducted  and if such  Borrower  or such
Subsidiary  has  established  appropriate  reserves  as  shall  be  required  in
conformity with GAAP.

         5.10 Maintenance of Properties;  Insurance. Each Borrower will maintain
or cause to be  maintained  in good  repair,  working  order and  condition  all
material  properties used in the business of such Borrower and its  Subsidiaries
and  will  make or  cause  to be made  all  appropriate  repairs,  renewals  and
replacements  thereof.  Borrowers will maintain or cause to be maintained,  with
financially sound and reputable  insurers,  public liability and property damage
insurance  with respect to their  respective  businesses  and properties and the
businesses  and  properties  of their  respective  Subsidiaries  against loss or
damage of the  kinds  customarily  carried  or  maintained  by  corporations  of
established  reputation  engaged in similar businesses and in amounts acceptable
to  Lender.  Borrowers  shall  cause  Lender  to be named  as loss  payee on all
insurance  policies  relating to any Collateral and as additional  insured under
all liability  policies,  in each case pursuant to appropriate  endorsements  in
form and  substance  satisfactory  to Lender  and shall  collaterally  assign to
Lender as security for the payment of the Obligations all business  interruption
insurance of  Borrowers.  Borrowers  shall apply any proceeds  received from any
policies of insurance relating to any Collateral to the Obligations as set forth
in subsection 2.4(B).

         5.11  Compliance  with Laws. Each Borrower will, and will cause each of
its Subsidiaries to, comply with the requirements of all applicable laws, rules,
regulations and orders of any governmental  authority as now in effect and which
may be imposed in the future in all  jurisdictions in which each Borrower or any
of its  Subsidiaries  is now doing business or may hereafter be doing  business,
other  than those laws the  noncompliance  with which  would not have a Material
Adverse Effect.

         5.12 Further  Assurances.  Each Borrower shall, and shall cause each of
its  Subsidiaries to, from time to time,  execute such guaranties,  financing or
continuation  statements,  documents,  security  agreements,  reports  and other
documents or deliver to Lender such instruments,  certificates of title or other
documents as Lender at any time may reasonably  request to evidence,  perfect or
otherwise implement the guaranties and security for repayment of the Obligations
provided for in the Loan Documents.  At Lender's request,  Borrowers shall cause
any Subsidiaries of Borrowers

                                    37


promptly to guaranty the Obligations and to grant to Lender  security  interests
in the real,  personal and mixed property of such Subsidiary to secure the
Obligations.

            5.13 Collateral  Locations.  Borrowers  will keep the Collateral at
the locations specified on Schedule 4.7. With respect to any new location (which
in any event shall be within the  continental  United  States),  Borrowers  will
execute  such  documents  and take such  actions as Lender  deems  necessary  to
perfect and protect the security interests of the Lender in the Collateral prior
to the transfer or removal of any Collateral to such new location.

           5.14  Bailees. If any Collateral is at any time in the possession or
control of any warehouseman, bailee or any of a Borrower's agents or processors,
such  Borrower  shall,  upon the request of Lender,  notify  such  warehouseman,
bailee,  agent or processor of the security interests in favor of Lender created
hereby and shall  instruct such Person to hold all such  Collateral for Lender's
account subject to Lender's instructions.

         5.15   Use of Proceeds and Margin  Security.  Borrowers shall use the
proceeds  of  all  Loans  for  proper  business  purposes  consistent  with  all
applicable laws, statutes, rules and regulations.  No portion of the proceeds of
any Loan shall be used by a Borrower or any of its  Subsidiaries for the purpose
of  purchasing or carrying of margin stock within the meaning of Regulation G or
Regulation U, or in any manner that might cause the borrowing or the application
of such proceeds to violate Regulation T or Regulation X or any other regulation
of the Board of  Governors  of the  Federal  Reserve  System,  or to violate the
Exchange Act.


                              6  FINANCIAL COVENANTS

      Borrowers  covenant  and agree  that so long as any of the  Commitments
remain in effect and until payment in full of all  Obligations,  Borrowers shall
comply with and shall cause each of their respective Subsidiaries to comply with
all covenants in this Section 6.

      6.1  Tangible Net Worth.  Borrowers  shall  maintain a consolidated
Tangible  Net Worth of at least the  amounts  set forth below at the end of each
quarter of a Fiscal Year set forth below.

                  Fiscal Quarter                               Amount

                  March 31, 1996                             $  500,000
                  June 30, 1996                               1,000,000
                  September 30, 1996                          1,500,000
                  December 31, 1996                           2,000,000
                  March 31, 1997                              2,500,000
                  June 30, 1997                               2,500,000
                  September 30, 1997                          2,700,000

                                                  38


                  December 31, 1997                           3,000,000
                  March 31, 1998                              3,500,000
                  June 30, 1998                               4,000,000
                  September 30, 1998                           4,750,000
                  December 31, 1998 and as of the
                  end of each       of each fiscal quarter
                  thereafter                                   5,250,000


      6.2  Minimum  EBITDA.  Borrowers  shall  at all  times  maintain  a
consolidated EBITDA less Registration Payments paid or accrued of at least the
amount set forth below for the applicable period set forth below.

                                             Editek &
          Period                             diAGnostix     PDLA   Consolidated

Two (2) Months ending February 29,         $  100,000  $    50,000 $  150,000
Three (3) months ending March 31, 1996        100,000      100,000     200,000
Four (4) months ending April 30, 1996         100,000      400,000     500,000
Five (5) months ending May 31, 1996           100,000      800,000     900,000
Six (6) months ending June 30, 1996           200,000    1,000,000   1,200,000
Seven (7) months ending July 31, 1996         200,000    1,400,000   1,600,000
Eight (8) months ending August 31, 1996       200,000    1,800,000   2,000,000
Nine (9) months ending September 30, 1996     200,000    2,100,000   2,300,000
Ten (10) months ending October 31, 1996       300,000    2,400,000   2,700,000
Eleven (11) months ending November 30, 1996   300,000    2,800,000   3,100,000
Twelve (12) month ending December 31, 1996    300,000    3,100,000   3,400,000
Twelve (12) month ending March 31, 1997       350,000    3,100,000   3,450,000
Twelve (12) month ending June 30, 1997        350,000    3,150,000   3,500,000
Twelve (12) month ending September 30, 1997   400,000    3,150,000   3,550,000
Twelve (12) month ending December 31, 1997    400,000    3,200,000   3,600,000
Twelve (12) month ending March 31, 1998       400,000    3,250,000   3,650,000
Twelve (12) month ending June 30, 1998        500,000    3,200,000   3,700,000
Twelve (12) month ending September 30, 1998   500,000    3,250,000   3,750,000
Twelve (12) month ending December 31, 1998
and for the twelve (12) months ending at the
end of each fiscal quarter thereafter         500,000    3,300,000    3,800,000

      6.3  Ratio of Indebtedness to Tangible Net Worth.  The ratio of (a)
Borrowers' consolidated Indebtedness to (b) Borrowers' consolidated Tangible Net
Worth,  shall be no  greater  than the ratio set forth  below at the end of each
quarter of a Fiscal Year set forth below.

                                      39



           Fiscal Quarter                                             Ratio

           March 31, 1996                                                7.5:1
           June 30, 1996                                                 7.5:1
           September 30, 1996                                            7.5:1
           December 31, 1996                                             7.5:1
           March 31, 1997                                                4.5:1
           June 30, 1997                                                 4.5:1
           September 30, 1997                                            4.5:1
           December 31, 1997                                             4.5:1
           March 31, 1998                                                3.0:1
           June 30, 1998                                                 3.0:1
           September 30, 1998                                            3.0:1
           December 31, 1998 and as of the
           end of each       of each fiscal quarter
           thereafter                                                    3.0:1

       6.4   Capital  Expenditure  Limits.  The  aggregate  amount  of  all
Capital Expenditures of Borrowers and their respective  Subsidiaries  (excluding
trade-ins and excluding Capital Expenditures in respect of replacement assets to
the extent funded with casualty insurance  proceeds) will not exceed $950,000 in
any Fiscal Year. In the event that a Borrower or any of its Subsidiaries  enters
into a  Capital  Lease or other  contract  with  respect  to fixed  assets,  for
purposes of calculating  Capital  Expenditures  under this subsection  only, the
amount of the Capital Lease or contract initially capitalized on such Borrower's
or  Subsidiary's  balance  sheet  prepared  in  accordance  with  GAAP  shall be
considered  expended in full on the date that such Borrower or Subsidiary enters
into such Capital Lease or contract.

       6.5   Fixed  Charge  Coverage.  Borrowers  shall  not  permit  their
consolidated  Fixed  Charge  Coverage  for any period set forth below to be less
than the amount set forth below for such period.

                        Period                                        Amount

         Three (3) Months ending March 31, 1996                        0.8
         Six (6) months ending June 30, 1996                           1.0
         Nine (9) months ending September 30, 1996                     1.3
         Twelve (12) month ending December 31, 1996                    1.3

                                       40



         Twelve (12) month ending March 31, 1997                       1.3
         Twelve (12) month ending June 30, 1997                        1.4
         Twelve (12) month ending September 30, 1997                   1.4
         Twelve (12) month ending December 31, 1997                    1.4
         Twelve (12) month ending March 31, 1998                       1.4
         Twelve (12) month ending June 30, 1998                        1.4
         Twelve (12) month ending September 30, 1998                   1.4
         Twelve (12) month ending December 31, 1998
         and for the twelve (12) months ending at the
         end of each fiscal quarter thereafter                          1.4

          6.6    Interest   Coverage.   Borrowers   shall  not   permit   their
consolidated  Interest  Coverage  for any period set forth below to be less than
the amount set forth below for such period.

                       Period                                        Amount

         Three (3) Months ending March 31, 1996                        3.0
         Six (6) months ending June 30, 1996                           3.4
         Nine (9) months ending September 30, 1996                     4.6
         Twelve (12) month ending December 31, 1996                    5.6
         Twelve (12) month ending March 31, 1997                       6.0
         Twelve (12) month ending June 30, 1997                        6.0
         Twelve (12) month ending September 30, 1997                   6.0
         Twelve (12) month ending December 31, 1997                    6.0
         Twelve (12) month ending March 31, 1998                       6.0
         Twelve (12) month ending June 30, 1998                        6.0
         Twelve (12) month ending September 30, 1998                   6.0
         Twelve (12) month ending December 31, 1998
         and for the twelve (12) months ending at the
         end of each fiscal quarter thereafter                         6.0


                          7   NEGATIVE COVENANTS

         Borrowers  covenant  and agree  that so long as any of the  Commitments
remain in effect and until payment in full of all Obligations,  unless Borrowers
have received the prior written consent of Lender,  Borrowers shall not and will
not permit any of their respective Subsidiaries to:

          7.1    Indebtedness and Liabilities.  Directly or indirectly  create,
incur,  assume,  guaranty,  or otherwise become or remain directly or indirectly
liable, on a fixed or contingent basis, with respect to any Indebtedness except:
(a) the  Obligations;  (b)  intercompany  Indebtedness,  not to exceed  $250,000
outstanding at any time in the aggregate,  among  Borrowers;  provided that such

                                          41



Indebtedness  is  subordinated  in  right of  payment  to the  Obligations;  (c)
Indebtedness  (excluding capital leases) not to exceed $100,000 in the aggregate
at any time outstanding  secured by purchase money Liens; (d) Indebtedness under
Capital Leases not to exceed $250,000  outstanding at any time in the aggregate;
and (e)  Indebtedness  existing on the Closing Date and  identified  on Schedule
7.1.  Except for  Indebtedness  described  permitted in the preceding  sentence,
Borrowers will not, and will not permit any of their respective Subsidiaries to,
incur any  Liabilities  except for trade  payables  and normal  accruals  in the
ordinary  course  of  business  not yet due and  payable  or with  respect  to a
Borrower or any of its  Subsidiaries  is  contesting in good faith the amount or
validity  thereof by  appropriate  proceedings  and then only to the extent that
such Borrower or Subsidiary  has  established  adequate  reserves  therefor,  if
appropriate under GAAP.

           7.2   Guaranties. Except for endorsements of instruments or items of
payment for collection in the ordinary course of business, guaranty, endorse, or
otherwise in any way become or be responsible  for any  obligations of any other
Person, whether directly or indirectly by agreement to purchase the indebtedness
of any other Person or through the purchase of goods,  supplies or services,  or
maintenance of working  capital or other balance sheet  covenants or conditions,
or by way of  stock  purchase,  capital  contribution,  advance  or loan for the
purpose of paying or discharging  any  indebtedness  or obligation of such other
Person or otherwise.

         7.3  Transfers, Liens and Related Matters.

         (A) Transfers.  Sell,  assign (by operation of law or  otherwise)  or
otherwise dispose of, or grant any option with respect to any of the  Collateral
or the assets of such Person,  except that Borrowers and their  respective
Subsidiaries  may (i) sell inventory in the ordinary course of business;  and
(ii) make Asset  Dispositions if all of the following  conditions are met:
(1) the market value of assets sold or  otherwise  disposed  of in any  single
transaction  or  series  of  related transactions  does not exceed  $25,000 and
the aggregate  market value of assets sold or otherwise  disposed of in any
Fiscal Year does not exceed  $50,000;  (2) the  consideration  received is at
least equal to the fair market value of such assets; (3) the sole consideration
received is cash;  (4) the net proceeds of such Asset Disposition are applied as
required by subsection  2.4(B);  (5) after giving effect to the sale or other
disposition of the assets included within the Asset  Disposition  and the
repayment  of the  Obligations  with  the  proceeds thereof, Borrowers are in
compliance on a pro forma basis with the covenants set forth in  Section  6
recomputed  for the most  recently  ended  month for which information  is
available  and  is in  compliance  with  all  other  terms  and conditions
contained in this Agreement;  and (6) no Default or Event of Default shall
then exist or result from such sale or other disposition.

     (B) Liens.  Except  for  Permitted  Encumbrances,  directly  or  indirectly
create,  incur, assume or permit to exist any Lien on or with  respect to any
of the  Collateral or the assets of such Person or any proceeds, income or
profits therefrom.

                                  42


     (C) No Negative Pledges.  Enter into or assume any agreement (other than
the Loan Documents) prohibiting the creation or assumption of any Lien upon its
properties or assets, whether now owned or hereafter acquired.

      (D) No Restrictions on Subsidiary  Distributions  to Borrowers.  Except as
provided  herein, directly or  indirectly  create or otherwise  cause or suffer
to exist or become effective any  consensual  encumbrance or restriction of any
kind on the ability of any such  Subsidiary to: (1) pay dividends or make any
other  distribution on any of such Subsidiary's  capital stock owned by a
Borrower or any Subsidiary of a Borrower; (2) subject to subordination
provisions,  pay any indebtedness owed to a Borrower or any other Subsidiary;
(3) make loans or advances to a Borrower or any other  Subsidiary;  or (4)
transfer  any of its  property or assets to a Borrower or any other
Subsidiary.

      7.4  Investments and Loans.  Make or permit to exist investments in
or loans to any other Person,  except:  (a) Cash Equivalents;  and (b) loans and
advances  to  employees  for  moving,  entertainment,  travel and other  similar
expenses in the ordinary course of business in an aggregate  outstanding  amount
not in excess of $50,000 at any time.


     7.5  Restricted  Junior Payments.  Directly or indirectly  declare,  order,
pay, make or set apart any sum for any Restricted Junior Payment, except that:

                  (a)  Subsidiaries  of  Borrowers  may make  Restricted  Junior
         Payments with respect to their common stock to the extent  necessary to
         permit  Borrowers to pay the  Obligations,  to make  Restricted  Junior
         Payments  permitted  under clause (b) below and to permit  Borrowers to
         pay expenses incurred in the ordinary course of business; and

                  (b) Editek may make dividend  payments on the Preferred  Stock
         and may make Registration Payments,  provided that all of the following
         limitations  shall be applicable to dividend  payments and Registration
         Payments:

                           (i)      no Default or Event of Default may be
                  existence at the time of such payment or
                  may be created by any such payment;

                           (ii)     no such payment may be made prior to
                  February 1, 1997;

                           (iii)    no such payment may be made prior to the
                  repayment in full of all principal of and interest on Term
                  Loan B;

                           (iv)     no such  payment may be made in any Fiscal
                  Year prior to the delivery to Lender of Borrowers' audited
                  financial statements for the previous Fiscal Year;

                                       43


                           (v) the  aggregate  amount of dividend  payments  and
                  Registration Payments in a Fiscal Year shall not exceed of the
                  lesser of (A) nine percent  (9%) of the amount of  outstanding
                  Preferred  Stock and (B) one-third of  Borrowers'  Excess Cash
                  Flow  for  the  previous   Fiscal  Year,  as  determined  from
                  Borrower's audited financial  statements  delivered to Lender;
                  and

                            (vi)  after  giving  effect  to  any  such  payment,
                  Availability shall not be less than $500,000.

      7.6 Restriction  on  Fundamental   Changes.  (a)  Enter  into  any
transaction  of merger or  consolidation,  except that a Borrower may merge with
another  Borrower and PDLA may merge with Princeton;  (b) liquidate,  wind-up or
dissolve itself (or suffer any liquidation or  dissolution);  (c) convey,  sell,
lease,  sublease,  transfer or  otherwise  dispose of, in one  transaction  or a
series of  transactions,  all or any substantial part of its business or assets,
or the capital stock of any of its Subsidiaries,  whether now owned or hereafter
acquired;  or (d) except  for the MedTox  Acquisition,  acquire by  purchase  or
otherwise all or any substantial  part of the business or assets of, or stock or
other evidence of beneficial ownership of, any Person.

       7.7  Changes Relating to Preferred Stock. Change or amend the terms
of the Preferred  Stock if the effect of such  amendment is to: (a) increase the
dividend rate thereon;  (b) change the  redemption  provisions  thereof;  or (c)
change or amend any other  term if such  change or  amendment  would  materially
increase the obligations of the obligor or confer additional  material rights on
the holder of such Preferred  Stock in a manner adverse to any Borrower,  any of
its Subsidiaries, or Lender.

     7.8 Transactions  with Affiliates.  Directly or indirectly,  enter
into or  permit  to exist  any  transaction  (including  the  purchase,  sale or
exchange of property or the rendering of any service) with any Affiliate or with
any officer,  director or employee of any Loan Party, except for transactions in
the ordinary course of and pursuant to the reasonable requirements of Borrowers'
business and upon fair and reasonable  terms which are fully disclosed to Lender
and  which are no less  favorable  to  Borrowers  than  they  would  obtain in a
comparable arm's length transaction with an unaffiliated Person.

      7.9  Environmental   Liabilities.   (a)  Violate   any   applicable
Environmental Law; (b) dispose of any Hazardous  Materials (except in accordance
with applicable  law) into or onto or from, any real property  owned,  leased or
operated  by any Loan  Party;  or (c) permit any Lien  imposed  pursuant  to any
Environmental Law to be imposed or to remain on any real property owned,  leased
or operated by any Loan Party.

                                     44



      7.10  Conduct of Business.  From and after the Closing Date,  engage
in any  business  other than  businesses  of the type engaged in by Borrowers or
such Subsidiary on the Closing Date.

     7.11  Compliance with ERISA. Establish any new Employee Benefit Plan
or amend any  existing  Employee  Benefit  Plan if the  liability  or  increased
liability  resulting  from such  establishment  or  amendment  is  material.  No
Borrower  nor any of its  Subsidiaries  shall fail to  establish,  maintain  and
operate each Employee  Benefit Plan in compliance in all material  respects with
the  provisions  of  ERISA,  the IRC  and  all  other  applicable  laws  and the
regulations and interpretations thereof.

      7.12  Tax  Consolidations.  File or consent to the filing of any
consolidated  income tax return  with any Person other than a Borrower or any of
its Subsidiaries.

     7.13  Subsidiaries.  Establish, create or acquire any new Subsidiaries.

     7.14  Fiscal Year.  Change its Fiscal Year.

     7.15  Press Release; Public Offering Materials. Disclose the name of
Lender in any press  release  or in any  prospectus,  proxy  statement  or other
materials  filed with any  governmental  entity relating to a public offering of
the capital stock of any Loan Party except as may be required by law.

     7.16 Bank  Accounts.  Establish any new bank  accounts,  or amend or
terminate any Blocked  Account or lockbox agreement.


                       8   DEFAULT, RIGHTS AND REMEDIES

     8.1 Event of Default.  "Event of Default"  shall mean the  occurrence or
existence of any one or more of the following:

          (A) Payment.  Failure  to make  payment of any of the  Obligations
when due and in the case of interest, such failure shall not be cured within
five (5) days of the applicable due date; or

          (B) Default in Other  Agreements.  (1) Failure of a Borrower or any of
its  Subsidiaries  to pay when due any  principal  or  interest  on any
Indebtedness  (other  than  the Obligations)  or (2)  breach  or  default  of
a  Borrower  or  any  of its  Subsidiaries with  respect  to  any  Indebtedness
(other  than  the Obligations);  if  such  failure to pay, breach or default
entitles  the  holder  to  cause  such  Indebtedness  having an  individual
principal  amount in excess of  $25,000  or having

                                    45


an  aggregate principal amount in excess of $50,000 to become or be declared due
prior to its stated maturity; or

           (C) Breach of Certain  Provisions.  Failure of  Borrowers to perform
or comply with any term or condition contained in subsections 5.1 (A), (B), (C)
and (R),  5.3, 5.5 or 5.6 or contained in Section 6 or Section 7; or

          (D) Breach of Warranty. Any representation, warranty, certification or
other statement made by any Loan Party in any Loan Document or in any statement
or  certificate at any time given by such Person in writing pursuant or in
connection  with any Loan Document is false in any material respect on the date
made; or

         (E) Other  Defaults  Under Loan  Documents.  A Borrower or any other
Loan Party  defaults in the  performance  of or compliance  with any term 
contained in this Agreement or the other Loan  Documents  and such default is
not remedied or waived within ten (10) days after  receipt by Borrowers of
notice  from  Lender of such  default (other than occurrences described in
other provisions of this subsection 8.1 for which a  different  grace  or cure
period  is  specified  or  which  constitute immediate Events of Default); or

        (F) Change  in  Control.  Editek  ceases  to  beneficially  own  and
control,  directly  or indirectly,  one hundred  percent  (100%) of the issued
and  outstanding  shares of each class of capital  stock of PDLA and diAGnostix;
or

        (G) Involuntary Bankruptcy;  Appointment of Receiver,  etc. (1) A court
enters a decree or order for relief  with  respect to a Borrower or any of its
Subsidiaries  in an involuntary  case  under  the  Bankruptcy  Code  or any
applicable  bankruptcy, insolvency  or other  similar law now or  hereafter  in
effect,  which decree or order is not stayed or other similar  relief is not
granted under any applicable federal or state law; or (2) the continuance of any
of the following events for sixty (60) days unless dismissed, bonded or
discharged: (a) an involuntary case is commenced against a Borrower or any of
its Subsidiaries, under any applicable bankruptcy, insolvency or other similar
law now or hereafter in effect; or (b) adecree  or order  of a court  for the
appointment  of a  receiver,  liquidator, sequestrator,  trustee,  custodian or
other officer having similar powers over a Borrower or any of its Subsidiaries,
or over all or a substantial part of their respective  property, is entered; or
(c) an interim receiver,  trustee or other custodian  is  appointed  without
the  consent  of a  Borrower  or  any  of its Subsidiaries,  for all or a
substantial part of the property of such Borrower or Subsidiary; or

         (H) Voluntary  Bankruptcy;  Appointment  of  Receiver,  etc.  (1) An
order  for  relief  is entered with respect to a Borrower or any of its
Subsidiaries,  or a Borrower or any of its Subsidiaries  commences a voluntary
case under the Bankruptcy Code or any applicable  bankruptcy,  insolvency or
other similar law now or hereafter in effect,  or consents to the entry of an
order for relief in an involuntary  case or to the conversion of an involuntary
case to a voluntary case under any such law or  consents  to the  appointment
of or taking  possession  by a  receiver, trustee or other

                               46


custodian for all or a substantial part of its property; or (2) a Borrower or
any of its Subsidiaries makes  any assignment for  the benefit of creditors; or
(3)  the  board  of  directors  of a  Borrower  or  any  of  its Subsidiaries
adopts any resolution or otherwise authorizes action to approve any of the
actions referred to in this subsection 8.1(H); or

         (I)  Liens.  Any lien,  levy or  assessment is filed or recorded with
respect to or otherwise imposed upon all or any part of the Collateral or the as
sets of a Borrower or any of its Subsidiaries by the United States or any
department or instrumentality thereof or by any state, county, municipality or
other governmental agency (other than Permitted Encumbrances) unless such lien,
levy or assessment is stayed, vacated, paid or discharged within ten (10) days
or Borrowers contest the validity thereof in good faith by appropriate
proceedings and establish appropriate reserves on their books in respect
thereof; or

         (J) Judgment and Attachments. Any money judgment, writ or warrant of
attachment,  or similar process involving (1) an amount in any individual case
in excess of $25,000 or (2) an amount in the  aggregate  at any time in excess
of $50,000 (in either  case not  adequately  covered  by  insurance  as to which
the  insurance company has acknowledged coverage) is entered or filed against a
Borrower or any of its Subsidiaries or any of their respective assets and
remains  undischarged, unvacated, unbonded or unstayed for a period of thirty
(30) days or in any event later than five (5) days prior to the date of any
proposed sale thereunder; or

         (K)  Dissolution.  Any  order,  judgment  or decree is entered  against
a Borrower  or any of its  Subsidiaries  decreeing the  dissolution  or split up
of a Borrower or that Subsidiary  and such order  remains  undischarged  or
unstayed  for a period in excess of twenty (20) days; or

         (L) Solvency.  A Borrower  ceases to be solvent (as  represented by
Borrowers in subsection 4.17) or admits in writing its present or prospective
inability to pay its debts as they become due; or

         (M) Injunction.  A Borrower or any of its  Subsidiaries  is enjoined,
restrained  or in any way  prevented  by the order of any court or any
administrative  or  regulatory agency from conducting all or any material part
of its business and such order continues for more than thirty (30) days; or

         (N) Invalidity of Loan  Documents.  Any of the Loan  Documents for any
reason,  other than a partial or full release in accordance  with the terms
thereof,  ceases to be in full  force and  effect or is  declared  to be null
and void,  or any Loan Party denies that it has any further liability under any
Loan Documents to which it is party, or gives notice to such effect; or

         (O)  Failure  of  Security.  Lender  does not have or ceases  to have a
valid  and  perfected first  priority  security  interest  in the  Collateral
(subject  to  Permitted Encumbrances),  in each case, for any reason other than
the failure of Lender to take any action within its control; or

                                    47



         (P) Damage,  Strike,  Casualty.  Any material  damage to, or loss,
theft or destruction of, any Collateral,  whether or not insured, or any strike,
lockout, labor dispute, embargo,  condemnation,  act of God or public  enemy,
or other  casualty  which causes,   for  more  than  fifteen  (15)  consecutive
days,  the  cessation  or substantial  curtailment  of revenue  producing
activities at any facility of a Borrower  or any of its  Subsidiaries  if any
such event or  circumstance  could reasonably be expected to have a Material
Adverse Effect; or

            (Q) Licenses and Permits.  The loss,  suspension or revocation of,
or failure to renew,  any license or permit now held or  hereafter  acquired
by a Borrower  or any of its Subsidiaries,  if such loss,  suspension,
revocation  or failure to renew could have a Material Adverse Effect; or

            (R)  Forfeiture.  There is filed  against a Borrower  any civil
or criminal  action,  suit or proceeding under any federal or state
racketeering  statute (including,  without limitation,  the Racketeer
Influenced  and Corrupt  Organization  Act of 1970), which action,  suit or
proceeding (1) is not dismissed within one hundred twenty (120)  days;
and (2) could  result in the  confiscation  or  forfeiture  of any
material portion of the Collateral; or

      8.2  Suspension of Commitments.  Upon the occurrence of any Default
or Event of Default,  notwithstanding any grace period or right to cure, Lender,
without notice or demand,  may immediately cease making additional Loans and the
Commitments shall be suspended;  provided that, in the case of a Default, if the
subject  condition  or event is waived or cured within any  applicable  grace or
cure period, the Commitments shall be reinstated.

      8.3  Acceleration.  Upon the  occurrence  of any  Event of  Default
described in the foregoing  subsections  8.1(G) or 8.1(H), all Obligations shall
automatically become immediately due and payable,  without presentment,  demand,
protest or other  requirements  of any kind,  all of which are hereby  expressly
waived by Borrowers,  and the Commitments  shall thereupon  terminate.  Upon the
occurrence and during the continuance of any other Event of Default, Lender may,
by written notice to Borrowers, declare all or any portion of the Obligations to
be, and the same shall  forthwith  become,  immediately  due and payable and the
Commitments shall thereupon terminate.

       8.4 Remedies.  If any Event of Default  shall have occurred and be
continuing,  in  addition  to and not in  limitation  of any rights or  remedies
available  to Lender at law or in equity,  Lender may exercise in respect of the
Collateral,  in addition to all other rights and remedies provided for herein or
otherwise  available  to it, all the rights and  remedies of a secured  party on
default  under  the  UCC  (whether  or not  the  UCC  applies  to  the  affected
Collateral)  and may also (a) notify any or all obligors on the Accounts to make
all payments directly to Lender;  (b) require Borrowers to, and Borrowers hereby
agree that they will,  at their  expense and upon  request of Lender  forthwith,
assemble  all or part of the  Collateral  as  directed  by  Lender  and  make it
available to Lender at a place to be  designated  by Lender which is  reasonably
convenient  to both parties;  (c) withdraw all cash in the Blocked  Accounts and
apply such  monies in  payment of the  Obligations  in

                                     48


the  manner  provided  in subsection  8.7; (d) without notice or demand or legal
process,  enter upon any premises of a Borrower and take  possession of the
Collateral;  and (e) without notice except as specified below, sell the
Collateral or any part thereof in one or more parcels at public or private sale,
at any of the  Lender's  offices or elsewhere,  at such time or times, for cash,
on credit or for future  delivery, and at such  price or  prices  and upon  such
other terms as Lender  may deem commercially  reasonable.  Borrowers agree that,
to the extent  notice of sale shall be required by law, at least ten (10) days
notice to Borrowers of the time and place of any public sale or the time after
which any private  sale is to be made shall constitute reasonable notification.
At any sale of the Collateral, if permitted by law,  Lender may bid (which bid
may be, in whole or in part, in the form of cancellation of indebtedness)  for
the purchase of the Collateral or any portion thereof for the account of Lender.
Lender shall not be obligated to make any sale of Collateral regardless of
notice of sale having been given. Borrowers shall remain liable for any
deficiency. Lender may adjourn any public or private sale from time to time by
announcement at the time and place fixed therefor, and such sale may, without
further notice, be made at the time and place to which it was so adjourned.  To
the extent permitted by law, Borrowers hereby specifically waive all rights of
redemption, stay or appraisal which it has or may have under any law now
existing  or  hereafter  enacted.  Lender  shall not be required to proceed
against any Collateral but may proceed against Borrowers directly.

     8.5 Appointment   of   Attorney-in-Fact.   Each  Borrower   hereby
constitutes and appoints Lender as such  Borrower's  attorney-in-fact  with full
authority  in the  place  and  stead  of such  Borrower  and in the name of such
Borrower, Lender or otherwise, from time to time in Lender's discretion while an
Event of Default is continuing to take any action and to execute any  instrument
that Lender may deem  necessary or advisable to accomplish  the purposes of this
Agreement,  including: (a) to ask, demand, collect, sue for, recover,  compound,
receive and give acquittance and receipts for moneys due and to become due under
or in respect of any of the Collateral;  (b) to adjust, settle or compromise the
amount or payment of any  Account,  or release  wholly or partly any customer or
obligor  thereunder  or allow any credit or  discount  thereon;  (c) to receive,
endorse,  and collect  any drafts or other  instruments,  documents  and chattel
paper, in connection  with clause (a) above;  (d) to file any claims or take any
action or institute any proceedings  that Lender may deem necessary or desirable
for the  collection of any of the  Collateral or otherwise to enforce the rights
of Lender with respect to any of the Collateral; and (e) to sign and endorse any
invoices,  freight  or express  bills,  bills of  lading,  storage or  warehouse
receipts, assignments, verifications and notices in connection with Accounts and
other documents  relating to the  Collateral.  The appointment of Lender as each
Borrower's  attorney and Lender's rights and powers are coupled with an interest
and are irrevocable until payment in full and complete performance of all of the
Obligations.

                                 49


     8.6  Limitation  on Duty of  Lender  with  Respect  to  Collateral.
Beyond the safe custody  thereof,  Lender shall have no duty with respect to any
Collateral in its  possession or control (or in the possession or control of any
agent or bailee) or with respect to any income  thereon or the  preservation  of
rights  against prior  parties or any other rights  pertaining  thereto.  Lender
shall  be  deemed  to  have  exercised   reasonable  care  in  the  custody  and
preservation  of the  Collateral in its possession if the Collateral is accorded
treatment  substantially  equal to that which Lender  accords its own  property.
Lender shall not be liable or  responsible  for any loss or damage to any of the
Collateral,  or for any diminution in the value thereof, by reason of the act or
omission of any warehouseman,  carrier,  forwarding  agency,  consignee or other
agent or bailee selected by Lender in good faith.

      8.7  Application  of Proceeds.  Upon the  occurrence and during the
continuance of an Event of Default, (a) Borrowers irrevocably waive the right to
direct the  application of any and all payments at any time or times  thereafter
received  by  Lender  from or on  behalf  of  Borrowers,  and  Borrowers  hereby
irrevocably agree that Lender shall have the continuing exclusive right to apply
and to reapply  any and all  payments  received  at any time or times  after the
occurrence  and  during  the  continuance  of an Event of  Default  against  the
Obligations  in such  manner as Lender may deem  advisable  notwithstanding  any
previous  entry by Lender upon any books and records and (b) the proceeds of any
sale of, or other  realization  upon, all or any part of the Collateral shall be
applied:  first, to all fees, costs and expenses incurred by Lender with respect
to this Agreement,  the other Loan Documents or the Collateral;  second,  to all
fees due and owing to Lender;  third,  to accrued  and  unpaid  interest  on the
Obligations;  fourth, to the principal  amounts of the Obligations  outstanding;
and fifth,  to any other  indebtedness  or  obligations of any Borrower owing to
Lender. Lender shall account to Borrowers for any surplus and Borrowers shall be
liable for any deficiency.

   8.8 License  of  Intellectual   Property.   Each  Borrower  hereby
assigns,  transfers and conveys to Lender, effective during the existence of any
Event of  Default  hereunder,  the  non-exclusive  right and  license to use all
Intellectual  Property owned or used by such Borrower together with any goodwill
associated therewith, all to the extent necessary to enable Lender to realize on
the  Collateral  and any  successor  or  assign  to enjoy  the  benefits  of the
Collateral. This right and license shall inure to the benefit of all successors,
assigns and transferees of Lender and its successors,  assigns and  transferees,
whether  by  voluntary  conveyance,  operation  of  law,  assignment,  transfer,
foreclosure, deed in lieu of foreclosure or otherwise. Such right and license is
granted free of charge, without requirement that any monetary payment whatsoever
be made to Borrowers by Lender.

    8.9  Canadian Remedies. If any Event of Default shall have occurred
and be  continuing,  in addition to and not in limitation of any other rights or
remedies  provided  for herein or any rights or remedies  available to Lender or
otherwise  available to it at law or in equity,  Lender shall have the following
rights, powers and remedies,  subject to compliance with the PPSA, in respect of
any of the Collateral to which the PPSA is applicable:

                                         50


                  (A) to  appoint  any  Person  to be an  agent  or any
         Person to be a receiver, manager or receiver and manager (herein called
         the  "Receiver")  of such  Collateral  and to remove  any  Receiver  so
         appointed  and to appoint  another if the Lender so  desires,  it being
         agreed that any Receiver  appointed  pursuant to the provisions of this
         Agreement will have all of the powers of the Lender  hereunder,  and in
         addition, will have the power to carry on the business of any Borrower;

                  (B) to make payments to parties having prior charges or
         encumbrances on properties on which any Borrower may hold charges or
         encumbrances;

                  (C) to take  possession  of all or any  part  of such
         Collateral  with  power  to exclude the Borrowers, their agents and
         servants therefrom;

                  (D) to preserve, protect and maintain such Collateral
         and make such replacements  thereof and additions thereto as the Lender
         may deem advisable;

                  (E) to enjoy and  exercise  all powers  necessary  or
         incidental to the  performance  of all  functions  provided for in this
         Agreement,  including,  without  limitation,  the power to  purchase on
         credit,  the power to borrow in any  Borrower's  name or in the name of
         the Receiver, the power to borrow on all or any part of such Collateral
         in priority to this  Agreement or otherwise for such purposes as may be
         approved by the Lender to be evidenced by a Receiver's certificate, and
         to advance its own money to the  Borrowers at such rates of interest as
         it may deem  reasonable,  provided  that the  Receiver may borrow money
         only with the prior consent of the Lender;

                 (F) to sell,  lease or  dispose of all or any part of
         such Collateral whether by public or private sale or lease or otherwise
         in such manner and on such terms as to the Lender may seem commercially
         reasonable,  including, without limitation, terms that provide time for
         payment or credit, provided that:

                                 (1) the Lender or the  Receiver  will not be
                  required to sell, lease or dispose of such Collateral, but may
                  peaceably and quietly take,  hold,  use,  occupy,  possess and
                  enjoy  such   Collateral,   without   molestation,   eviction,
                  hindrance or  interruption by any Borrower or any other person
                  or persons whomsoever;

                                  (2)      the  Lender or the  Receiver  may
                  convey,  transfer  and  assign to a purchaser or purchasers
                  the title to any of such Collateral so sold; and

                                  (3) the  Borrowers  will be  entitled  to be
                  credited with the actual  proceeds of any such sale,  lease or
                  other  disposition only when such proceeds are received by the
                  Lender or the Receiver in cash;

                                       51



                           (G) to seize, collect,  demand, enforce,  recover and
         receive all or any part of the Accounts,  and to notify account debtors
         of the  Borrowers to pay such  Accounts to the Lender or the  Receiver,
         and to give valid and binding  receipts and discharges  therefor and in
         respect thereof, and to compromise all or any part of the Accounts that
         may seem bad or  doubtful  to the Lender or the  Receiver,  and to give
         time for payment thereof, with or without security;

                           (H) to enjoy and exercise all of the rights and 
         remedies of a secured  party under the PPSA;

                           (I) to dispose of all or any part of such  Collateral
         in the  condition  in  which it was on the  date  possession  of it was
         taken,  or after any  commercially  reasonable  repair,  processing  or
         preparation for disposition;

                           (J) if such  Collateral is perishable,  or the Lender
         or the Receiver  believes on  reasonable  grounds that any part of such
         Collateral will decline speedily in value, such Collateral is of a type
         customarily sold on a recognized  market,  the cost of care and storage
         of such Collateral is  disproportionately  large relative to its value,
         or the  Receiver  disposes  of such  Collateral  in the  course  of the
         Borrowers' business,  then the Lender or Receiver may sell or otherwise
         dispose  of any  part of such  Collateral  without  giving  any  notice
         whatsoever;

                           (K) to commence,  continue or defend  proceedings  in
         any court of  competent  jurisdiction  in the name of the  Lender,  the
         Receiver  or any  Borrower  for the  purpose of  exercising  any of the
         rights,  powers and remedies set out in this subsection 8.09, including
         the  institution  of  proceedings  for the  appointment  of a receiver,
         manager or receiver and manager of such Collateral; and

                           (L) at the sole option of the Lender, elect to retain
         all or any part of such Collateral in satisfaction of the Obligations.

      8.10  Waivers,  Non-Exclusive  Remedies.  No  failure on the part of
Lender to  exercise,  and no delay in  exercising  and no course of dealing with
respect to, any right under this  Agreement  or the other Loan  Documents  shall
operate as a waiver thereof;  nor shall any single or partial exercise by Lender
of any right under this Agreement or any other Loan Document  preclude any other
or further  exercise  thereof or the exercise of any other right.  The rights in
this Agreement and the other Loan Documents are cumulative and are not exclusive
of any other remedies provided by law.

      8.11 Judgment. 

                                       52


                        (A) If for the purposes of obtaining judgment in any
court it is necessary to convert a sum due hereunder or under any instrument
delivered  hereunder in any currency (the "Original Currency") into another
currency (the "Other Currency"), the parties hereto agree, to the fullest
extent  permitted by law, that the rate of  exchange  used  shall be that at
which in  accordance  with  normal  banking procedures  the Lender  could
purchase  the  Original  Currency  with the Other Currency on the Business
Day preceding that on which the payment is made.

                         (B) The obligation of any Borrower with respect to any
sum due from it to the Lender  hereunder  or  under  such  instrument  shall,
notwithstanding any judgment in any Other  Currency,  be discharged  only  to
the extent that on the Business Day following receipt by the Lender of any sum
adjudged to be so due in the Other Currency, the Lender may, in accordance with
normal  banking  procedures,  purchase  the Original  Currency  with the Other
Currency.  If the amount of the Original Currency so purchased is less than the
sum  originally  due to the Lender in the Original  Currency,  such Borrower
agrees to indemnify the Lender  against such loss,  and if the amount of the
Original  Currency so purchased  exceeds the sum originally  due to the Lender
in the  Original  Currency,  the Lender  agrees to remit  to  the  Borrowers
such  excess.  This  indemnity  shall  constitute  an obligation separate and
independent from the other obligations contained in this Agreement,  shall give
rise to a separate and independent cause of action, shall apply irrespective of
any indulgence granted by the Lender from time to time and shall  continue in
full force and effect  notwithstanding  any judgment or order for a liquidated
sum in  respect  of any  amount  due  hereunder  or under any judgment or order.

                        9      MISCELLANEOUS

    9.1  Assignments and  Participations.  Lender may assign its rights
and delegate its  obligations  under this  Agreement and further may assign,  or
sell  participations  in, all or any part of the Loans,  the  Commitments or any
other interest  herein to an Affiliate or to another  Person.  In the case of an
assignment authorized under this subsection 9.1, the assignee shall have, to the
extent of such assignment, the same rights, benefits and obligations as it would
if it were a Lender  hereunder.  Lender  shall be  relieved  of its  obligations
hereunder with respect to the Commitments or assigned portion thereof. Borrowers
hereby  acknowledge  and agree  that any  assignment  will give rise to a direct
obligation  of  Borrowers  to the  assignee  and  that  the  assignee  shall  be
considered  to be a  "Lender".  Lender may furnish  any  information  concerning
Borrowers and their respective  Subsidiaries in its possession from time to time
to   assignees   and   participants   (including   prospective   assignees   and
participants).

       9.2  Set Off. In addition  to any rights now or  hereafter  granted
under  applicable law and not by way of limitation of any such rights,  upon the
occurrence of any Event of Default,  Lender, each assignee of Lender's interest,
and each participant is hereby  authorized by Borrowers at any time or from time
to time,  without  notice to Borrowers or to any other  Person,  any such notice
being hereby  expressly  waived,  to set off and to appropriate and to apply any
and all balances  held

                                            53


by it at any of its offices for the account of a Borrower or any of its
Subsidiaries  (regardless of whether such balances are then due to a Borrower
or its Subsidiaries) and any other property at any time held or owing by that
Lender or assignee to or for the credit or for the account of a Borrower
against and on account of any of the  Obligations  then  outstanding;  provided,
that no participant  shall exercise such right without the prior written consent
of Lender.

      Borrowers  hereby agree,  to the fullest extent  permitted by law, that
any  Lender,  assignee  or  participant  may  exercise  its right of setoff with
respect to amounts in excess of its pro rata share of the  Obligations  (or,  in
the case of a participant,  in excess of its pro rata participation  interest in
the Obligations) and that such Lender, assignee or participant,  as the case may
be,  shall be deemed to have  purchased  for cash in the amount of such  excess,
participations in each other Lender's or holder's share of the Obligations.

        9.3  Expenses and Attorneys' Fees.  Whether or not the transactions
contemplated  hereby shall be  consummated,  Borrowers agree to promptly pay all
reasonable  fees,  costs and expenses  incurred by Lender in connection with any
matters  contemplated  by or  arising  out of this  Agreement  or the other Loan
Documents  including the  following,  and all such  reasonable  fees,  costs and
expenses shall be part of the Obligations,  payable on demand and secured by the
Collateral:  (a)  reasonable  fees,  costs and  expenses  (including  reasonable
attorneys'  fees,  allocated  costs of internal  counsel and reasonable  fees of
environmental  consultants,  accountants  and other  professionals  retained  by
Lender)  incurred in  connection  with the  examination,  review,  due diligence
investigation, documentation and closing of the financing arrangements evidenced
by the Loan  Documents;  (b)  reasonable  fees,  costs and  expenses  (including
reasonable  attorneys' fees,  allocated costs of internal counsel and reasonable
fees of environmental consultants,  accountants and other professionals retained
by Lender)  incurred in connection  with the review,  negotiation,  preparation,
documentation,  execution and  administration of the Loan Documents,  the Loans,
and any amendments,  waivers,  consents,  forbearances  and other  modifications
relating  thereto  or  any  subordination  or  intercreditor   agreements;   (c)
reasonable  fees,  costs and  expenses  incurred  in  creating,  perfecting  and
maintaining  perfection of Liens in favor of Lender;  (d) reasonable fees, costs
and expenses incurred in connection with forwarding to Borrowers the proceeds of
Loans including Lender's standard wire transfer fee; (e) reasonable fees, costs,
expenses and bank charges,  including bank charges for returned checks, incurred
by Lender in establishing,  maintaining and handling lock box accounts,  blocked
accounts or other  accounts for  collection of the  Collateral;  (f)  reasonable
fees, costs,  expenses (including reasonable attorneys' fees and allocated costs
of internal  counsel) and costs of  settlement  incurred in  collecting  upon or
enforcing  rights  against the  Collateral  or incurred in any action to enforce
this  Agreement or the other Loan  Documents or to collect any payments due from
Borrowers  or any other  Loan  Party  under  this  Agreement  or any other  Loan
Document or incurred in connection with any refinancing or  restructuring of the
credit  arrangements  provided under this Agreement,  whether in the nature of a
"workout" or in connection  with any  insolvency or  bankruptcy  proceedings  or
otherwise.
 
                                           54


      9.4 Indemnity.  In addition to the payment of expenses pursuant to
subsection 9.3,  whether or not the  transactions  contemplated  hereby shall be
consummated,  Borrowers  agree  to  indemnify,  pay  and  hold  Lender,  and the
officers, directors,  employees, agents, consultants,  auditors, persons engaged
by Lender to evaluate or monitor the  Collateral,  affiliates  and  attorneys of
Lender and such holders  (collectively  called the "Indemnitees")  harmless from
and against any and all liabilities,  obligations,  losses, damages,  penalties,
actions, judgments, suits, claims, costs, expenses and disbursements of any kind
or nature whatsoever (including the reasonable fees and disbursements of counsel
for such  Indemnitees in connection with any  investigative,  administrative  or
judicial  proceeding  commenced or  threatened,  whether or not such  Indemnitee
shall be  designated a party  thereto)  that may be imposed on,  incurred by, or
asserted  against that  Indemnitee,  in any manner relating to or arising out of
this Agreement or the other Loan Documents, the consummation of the transactions
contemplated  by this  Agreement,  the  statements  contained in the  commitment
letters,  if any,  delivered  by Lender,  Lender's  agreement  to make the Loans
hereunder,  the use or intended  use of the  proceeds of any of the Loans or the
exercise of any right or remedy hereunder or under the other Loan Documents (the
"Indemnified Liabilities");  provided that Borrowers shall have no obligation to
an Indemnitee hereunder with respect to Indemnified Liabilities arising from the
gross  negligence or willful  misconduct  of that  Indemnitee as determined by a
court of competent jurisdiction.

       9.5   Amendments   and   Waivers.   No   amendment,    modification,
termination  or waiver of any  provision of this  Agreement or of the other Loan
Documents,  or  consent  to any  departure  by  Borrowers  therefrom,  shall  be
effective  unless  the  same  shall be in  writing  and  signed  by  Lender  and
Borrowers.  Each  amendment,  modification,   termination  or  waiver  shall  be
effective only in the specific  instance and for the specific  purpose for which
it was given.

       9.6  Notices.  Unless otherwise  specifically  provided herein, all
notices shall be in writing addressed to the respective party as set forth below
and may be personally served, telecopied or sent by overnight courier service or
United  States mail and shall be deemed to have been given:  (a) if delivered in
person,  when  delivered;   (b)  if  delivered  by  telecopy,  on  the  date  of
transmission if transmitted on a Business Day before 4:00 p.m.  Chicago time or,
if not, on the next  succeeding  Business  Day;  (c) if  delivered  by overnight
courier, two (2) days after delivery to such courier properly addressed;  or (d)
if by U.S.  Mail,  four (4) Business Days after  depositing in the United States
mail, with postage prepaid and properly addressed.


   If to Borrowers:                            Editek, Inc.
                                               1238 Anthony Road
                                               Burlington, North Carolina  27215
                                               Attention: President
                                               Telecopy No.: (910) 229-4471

                                    55



    With a copy to:                        Petree Stockton, L.L.P.
                                           4101 Lake Boone Trail, Suite 400
                                           Raleigh, North Carolina  27607-6519
                                           Attention: James F. Verdonik
                                           Telecopy No.: (919) 420-1800


     If to Lender:                          HELLER FINANCIAL, INC.
                                            Attn:  HBC Portfolio Manager
                                            500 West Monroe Street
                                            Chicago, Illinois 60661
                                            Telecopy No.: (312) 441-6969

     With a copy to:                         HELLER FINANCIAL, INC.
                                             Attn:  Legal Department
                                             500 West Monroe Street
                                             Chicago, Illinois 60661
                                             Telecopy No. (312) 441-7367

or to such other address as the party addressed shall have previously designated
by written notice to the serving party, given in accordance with this subsection
9.6.

      9.7  Survival of Warranties and Certain Agreements. All agreements,
representations  and  warranties  made herein shall  survive the  execution  and
delivery   of  this   Agreement   and  the   making  of  the  Loans   hereunder.
Notwithstanding  anything in this  Agreement or implied by law to the  contrary,
the agreements of Borrowers set forth in  subsections  9.3 and 9.4 shall survive
the payment of the Loans and the termination of this Agreement.

      9.8  Indulgence  Not  Waiver.  No  failure  or delay on the part of
Lender in the exercise of any power, right or privilege shall impair such power,
right or privilege or be construed to be a waiver of any default or acquiescence
therein,  nor shall any single or partial  exercise of any such power,  right or
privilege  preclude  other or further  exercise  thereof or of any other  right,
power or privilege.

     9.9  Marshaling;  Payments Set Aside. Lender shall not be under any
obligation  to marshal  any assets in favor of any Loan Party or any other party
or against or in payment of any or all of the  Obligations.  To the extent  that
any Loan Party  makes a payment or  payments  to Lender or Lender  enforces  its
security  interests  or  exercise  its  rights of  setoff,  and such  payment or
payments or the proceeds of such  enforcement  or setoff or any part thereof are
subsequently invalidated,  declared to be fraudulent or preferential,  set aside
and/or required to be repaid to a trustee, receiver or any other party under any
bankruptcy law, state or federal law, common law or equitable cause, then to the
extent of such recovery,  the Obligations or part thereof originally intended to
be satisfied,  and all Liens, rights and remedies therefor, shall be revived and
continued

                                   56


in full force and effect as if such payment had not been made or such
enforcement or setoff had not occurred.

      9.10  Entire  Agreement.  This  Agreement,  the Term Notes,  and the
other Loan Documents referred to herein embody the final, entire agreement among
the parties  hereto and  supersede  any and all prior  commitments,  agreements,
representations,  and  understandings,  whether written or oral, relating to the
subject  matter  hereof and may not be  contradicted  or varied by  evidence  of
prior,  contemporaneous,  or subsequent  oral  agreements or  discussions of the
parties hereto. There are no oral agreements among the parties hereto.

      9.11 Independence  of Covenants.  All covenants  hereunder shall be
given  independent  effect so that if a  particular  action or  condition is not
permitted  by any of such  covenants,  the fact that it would be permitted by an
exception to, or be otherwise  within the limitations of, another covenant shall
not avoid the  occurrence  of a Default or an Event of Default if such action is
taken or condition exists.

      9.12 Severability.  The invalidity,  illegality or unenforceability
in any  jurisdiction  of any provision in or obligation  under this Agreement or
the other Loan  Documents  shall not affect or impair the validity,  legality or
enforceability of the remaining  provisions or obligations under this Agreement,
or the other Loan  Documents  or of such  provision or  obligation  in any other
jurisdiction.

       9.13  Headings.  Section and  subsection  headings in this Agreement
are included herein for convenience of reference only and shall not constitute a
part of this Agreement for any other purpose or be given any substantive effect.

       9.14  APPLICABLE LAW. THIS AGREEMENT SHALL BE GOVERNED BY, AND SHALL
BE CONSTRUED AND ENFORCED IN ACCORDANCE  WITH, THE INTERNAL LAWS OF THE STATE OF
ILLINOIS, WITHOUT REGARD TO CONFLICTS OF LAWS PRINCIPLES.

      9.15  Successors and Assigns.  This Agreement  shall be binding upon
and inure to the benefit of the parties hereto and their  respective  successors
and assigns  except that  Borrowers  may not assign their rights or  obligations
hereunder without the prior written consent of Lender.
 
     9.16   No Fiduciary Relationship; Limitation of Liabilities. 

                           (A)       No provision in this  Agreement or in any
of the other Loan  Documents  and no course of dealing  between the parties
shall be deemed to create any  fiduciary duty by Lender to Borrowers.

                                     57

                           (B)       Neither Lender, nor any affiliate, officer,
director,  shareholder, employee, attorney, or agent of Lender  shall have any
liability  with  respect  to, and Borrowers  hereby  waive,  release,  and
agree not to sue any of them upon,  any claim for any special,  indirect,
incidental, or consequential damages suffered or incurred  by  Borrowers  in
connection  with,  arising out of, or in any way related to, this  Agreement
or   any   of the   other   Loan  Documents,  or   any   of   the
transactions  contemplated by this Agreement or any of the other Loan Documents.
Borrowers hereby waive,  release, and agree not to sue Lender or any of Lender's
affiliates,  officers, directors,  employees,  attorneys, or agents for punitive
damages in respect of any claim in  connection  with,  arising out of, or in any
way related to, this Agreement or any of the other Loan Documents, or any of the
transactions   contemplated  by  this  Agreement  or  any  of  the  transactions
contemplated hereby.

      9.17  CONSENT TO JURISDICTION.  EACH BORROWER HEREBY CONSENTS TO THE
JURISDICTION  OF ANY STATE OR FEDERAL COURT  LOCATED  WITHIN THE COUNTY OF COOK,
STATE OF ILLINOIS AND IRREVOCABLY AGREES THAT, SUBJECT TO LENDER'S ELECTION, ALL
ACTIONS OR PROCEEDINGS  ARISING OUT OF OR RELATING TO THIS  AGREEMENT,  THE TERM
NOTES OR THE OTHER  LOAN  DOCUMENTS  SHALL BE  LITIGATED  IN SUCH  COURTS.  EACH
BORROWER ACCEPTS FOR ITSELF AND IN CONNECTION WITH ITS PROPERTIES, GENERALLY AND
UNCONDITIONALLY,  THE  NON-EXCLUSIVE  JURISDICTION  OF THE AFORESAID  COURTS AND
WAIVES ANY DEFENSE OF FORUM NON CONVENIENS,  AND IRREVOCABLY  AGREES TO BE BOUND
BY ANY JUDGMENT  RENDERED  THEREBY IN CONNECTION WITH THIS  AGREEMENT,  THE TERM
NOTES, THE OTHER LOAN DOCUMENTS OR THE OBLIGATIONS.

       9.18   WAIVER OF JURY TRIAL.  EACH  BORROWER AND LENDER  HEREBY WAIVE
THEIR  RESPECTIVE  RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION  BASED
UPON OR  ARISING  OUT OF THIS  AGREEMENT,  THE  TERM  NOTES  OR THE  OTHER  LOAN
DOCUMENTS.  BORROWERS  AND  LENDER  ACKNOWLEDGE  THAT THIS  WAIVER IS A MATERIAL
INDUCEMENT TO ENTER INTO A BUSINESS  RELATIONSHIP,  THAT EACH HAS ALREADY RELIED
ON THE WAIVER IN ENTERING INTO THIS AGREEMENT, THE TERM NOTES AND THE OTHER LOAN
DOCUMENTS  AND THAT EACH WILL  CONTINUE  TO RELY ON THE WAIVER IN THEIR  RELATED
FUTURE  DEALINGS.  BORROWERS AND LENDER FURTHER  WARRANT AND REPRESENT THAT EACH
HAS REVIEWED  THIS WAIVER WITH ITS LEGAL  COUNSEL,  AND THAT EACH  KNOWINGLY AND
VOLUNTARILY  WAIVES  ITS JURY TRIAL  RIGHTS  FOLLOWING  CONSULTATION  WITH LEGAL
COUNSEL.

       9.19   Construction.  Each Borrower and Lender each  acknowledge that
it has had the benefit of legal  counsel of its own choice and has been afforded
an  opportunity  to review this  Agreement and the other Loan Documents with its
legal  counsel and that this  Agreement  and the other Loan  Documents  shall be
construed as if jointly drafted by Borrowers and Lender.

                                  58

          9.20  Counterparts;    Effectiveness.   This   Agreement   and   any
amendments,  waivers,  consents, or supplements may be executed in any number of
counterparts and by different parties hereto in separate  counterparts,  each of
which when so executed and  delivered  shall be deemed an  original,  but all of
which  counterparts  together shall  constitute but one and the same instrument.
This Agreement shall become effective upon the execution of a counterpart hereof
by each of the parties hereto.

          9.21  No Duty. All  attorneys,  accountants,  appraisers,  and other
professional  Persons and consultants retained by Lender shall have the right to
act  exclusively in the interest of Lender and shall have no duty of disclosure,
duty of loyalty, duty of care, or other duty or obligation of any type or nature
whatsoever  to  Borrowers  or any of any  Borrower's  shareholders  or any other
Person.

          9.22  Confidentiality.  Lender shall hold all nonpublic  information
identified  as such by  Borrowers in  accordance  with such  Person's  customary
procedures  for  handling  confidential   information  of  this  nature  and  in
accordance  with safe and  sound  business  practices  and in any event may make
disclosure   reasonably  required  by  a  bona  fide  offeree  or  assignee  (or
participation),  or as required or  requested by any  Governmental  Authority or
representative  thereof,  or pursuant to legal process,  or to its  accountants,
lawyers and other  advisors,  and shall require any such offeree or assignee (or
participant)   to  agree  (and  require  any  of  its  offerees,   assignees  or
participants  to agree) to comply  with this  Section  9.22.  In no event  shall
Lender be obligated or required to return any materials  furnished by Borrowers;
provided,  however,  each Offeree shall be required to agree that if it does not
become a assignee (or participant) it shall return all materials furnished to it
by Borrowers in connection herewith.





                      [Signatures appear on following page]


                                     59





         Loan and Security Agreement - Signature Page
                                 

         Witness the due  execution  hereof by the  respective  duly  authorized
officers of the undersigned as of the date first written above.


                                                 HELLER FINANCIAL, INC.


                                                  By:

                                                  Title:
                                                 
                                                  EDITEK, INC.

                                                  By:

                                                  Title:

                                                  FEIN:


                                                  PSYCHIATRIC DIAGNOSTIC
                                                  LABORATORIES OF AMERICA, INC.

                                                   By:

                                                   Title:

                                                   FEIN:


                                                   DIAGNOSTIX, INC.

                                                   By:

                                                   Title:

                                                   FEIN:


                                         60




                           LOAN AND SECURITY AGREEMENT

                          DATED AS OF JANUARY ___, 1996

                                     between

                                  EDITEK, INC.
              PSYCHIATRIC DIAGNOSTIC LABORATORIES OF AMERICA, INC.
                                DIAGNOSTIX, INC.

                                  as Borrowers

                                       and

                             HELLER FINANCIAL, INC.

                                    as Lender


                                        61




                                TABLE OF CONTENTS


         SECTION 1  DEFINITIONS

         1.1      Certain Defined Terms......................................  1
         1.2      Accounting Terms........................................... 11
         1.3      Other Definitional Provisions.............................. 12

         SECTION 2  LOANS AND COLLATERAL

         2.1      Loans...................................................... 12
                  (A)(1)   Term Loan A....................................... 12
                  (A)(2)   Term Loan B....................................... 13
                  (B)      Revolving Loan...................     ............ 14
                  (C)      Eligible Collateral...................   ......... 15
                  (D)      Borrowing Mechanics............................... 17
                  (E)      Term Notes........................................ 18
                  (F)      Evidence of Revolving Loan Obligations............ 18
         2.2      Interest................................................... 18
                  (A)      Rate of Interest......................... ........ 18
                  (B)      Computation and Payment of Interest............... 18
                  (C)      Interest Laws..................................... 18
         2.3      Fees....................................................... 19
                  (A)      Closing Fee....................................... 19
                  (B)      Unused Line Fee................................... 19
                  (C)      Prepayment Fees..................................  19
                  (D)      Collateral Monitoring Fee......................... 20
                  (E)      Audit Fees........................................ 20
                  (F)      Other Fees and Expenses........................... 20
         2.4      Payments and Prepayments................................... 20
                  (A)      Manner and Time of Payment........................ 20
                  (B)      Mandatory Prepayments............................. 21
                           (1)      Overadvance.............................. 21
                           (2)      Proceeds of Asset Dispositions........... 21
                           (3)      Prepayments from Excess Cash Flow........ 21
                  (C)      Voluntary Prepayments and Repayments.............  21
                  (D)      Payments on Business Days......................... 22
         2.5      Term of this Agreement..................................... 22
         2.6      Statements................................................. 22
         2.7      Grant of Security Interest................................. 22
         2.8      Capital Adequacy and Other Adjustments..................... 23

                                                 i


                  (A)      No Deductions..................................... 23
                  (B)      Changes in Tax Laws............................... 23

         SECTION 3  CONDITIONS TO LOANS

         3.1      Conditions to Loans........................................ 24
                  (A)      Closing Deliveries................................ 24
                  (B)      Security Interests................................ 24
                  (C)      Closing Date Availability......................... 24
                  (D)      Representations and Warranties.................... 24
                  (E)      Fees.............................................. 25
                  (F)      No Default........................................ 25
                  (G)      Performance of Agreements......................... 25
                  (H)      No Prohibition.................................... 25
                  (I)      No Litigation..................................... 25
                  (J)      Issuance of Preferred Stock....................... 25
                  (K)      MedTox Acquisition................................ 25

         SECTION 4  BORROWERS' REPRESENTATIONS AND WARRANTIES

         4.1      Organization, Powers, Capitalization....................... 26
                  (A)      Organization and Powers........................... 26
                  (B)      Capitalization.................................... 26
         4.2      Authorization of Borrowing, No Conflict................ ... 26
         4.3      Financial Condition........................................ 27
         4.4      Indebtedness and Liabilities............................... 27
         4.5      Account Warranties......................................... 27
         4.6      Names...................................................... 27
         4.7      Locations; FEIN............................................ 27
         4.8      Title to Properties; Liens................................. 27
         4.9      Litigation; Adverse Facts.................................. 28
         4.10     Payment of Taxes........................................... 28
         4.11     Performance of Agreements.................................. 28
         4.12     Employee Benefit Plans..................................... 28
         4.13     Intellectual Property...................................... 28
         4.14     Broker's Fees.............................................. 29
         4.15     Environmental Compliance................................... 29
         4.16     Solvency................................................... 29
         4.17     Disclosure................................................. 29
         4.18     Insurance.................................................. 29
         4.19     Compliance with Laws....................................... 30
         4.20     Bank Accounts.............................................. 30

                                                       ii


         4.21     Subsidiaries............................................... 30
         4.22     Employee Matters........................................  . 30
         4.23     Governmental Regulation.....................................30

                                                        iii

         SECTION 5  AFFIRMATIVE COVENANTS

         5.1      Financial Statements and Other Reports..................... 31
                  (A)      Monthly Financials................................ 31
                  (B)      Quarterly Financials.............................. 31
                  (C)      Year-End Financials............................... 31
                  (D)      Accountants' Certification and Reports............ 32
                  (E)      Compliance Certificate............................ 32
                  (F)      Borrowing Base Certificates, Registers and
                           Journals.......................................... 32
                  (G)      Management Report........................... ..... 33
                  (H)      Appraisals........................................ 33
                  (I)      Government Notices................................ 33
                  (J)      Events of Default, etc............................ 34
                  (K)      Trade Names....................................... 34
                  (L)      Locations......................................... 34
                  (M)      Bank Accounts..................................... 34
                  (N)      Litigation........................................ 34
                  (O)      Projections....................................... 34
                  (P)      Preferred Stock and Indebtedness Notice........... 34
                  (Q)      Other Information................................. 35
                  (R)      Opening Balance Sheet............................. 35
         5.2      Access to Accountants...................................... 35
         5.3      Inspection................................................. 35
         5.4      Collateral Records......................................... 35
         5.5      Account Covenants; Verification............................ 35
         5.6      Collection of Accounts and Payments........................ 36
         5.7      Endorsement................................................ 36
         5.8      Corporate Existence........................................ 36
         5.9      Payment of Taxes........................................... 36
         5.10     Maintenance of Properties; Insurance....................... 37
         5.11     Compliance with Laws....................................... 37
         5.12     Further Assurances......................................... 37
         5.13     Collateral Locations....................................... 37
         5.14     Bailees.................................................... 38
         5.15     Use of Proceeds and Margin Security........................ 38

         SECTION 6  FINANCIAL COVENANTS

         6.1      Tangible Net Worth......................................... 38
         6.2      Minimum EBITDA............................................. 39
         6.3      Ratio of Indebtedness to Tangible Net Worth................ 39
         6.4      Capital Expenditure Limits................................. 40

                                            iv


         6.5      Fixed Charge Coverage...................................... 40
         6.6      Interest Coverage.......................................... 40

         SECTION 7  NEGATIVE COVENANTS

         7.1      Indebtedness and Liabilities............................... 41
         7.2      Guaranties................................................. 42
         7.3      Transfers, Liens and Related Matters....................... 42
                  (A)      Transfers......................................... 42
                  (B)      Liens............................................. 42
                  (C)      No Negative Pledges............................... 42
                  (D)      No Restrictions on Subsidiary Distributions to 
                           Borrowers......................................... 42
         7.4      Investments and Loans...................................... 43
         7.5      Restricted Junior Payments................................. 43
         7.6      Restriction on Fundamental Changes......................... 43
         7.7      Changes Relating to Preferred Stock........................ 44
         7.8      Transactions with Affiliates............................... 44
         7.9      Environmental Liabilities.................................. 44
         7.10     Conduct of Business........................................ 44
         7.11     Compliance with ERISA...................................... 44
         7.12     Tax Consolidations......................................... 44
         7.13     Subsidiaries............................................... 44
         7.14     Fiscal Year................................................ 44
         7.15     Press Release; Public Offering Materials................... 45
         7.16     Bank Accounts.............................................. 45

         SECTION 8  DEFAULT, RIGHTS AND REMEDIES

         8.1      Event of Default........................................... 45
                  (A)      Payment........................................... 45
                  (B)      Default in Other Agreements....................... 45
                  (C)      Breach of Certain Provisions...................... 45
                  (D)      Breach of Warranty................................ 45
                  (E)      Other Defaults Under Loan Documents............... 45
                  (F)      Change in Control................................. 46
                  (G)      Involuntary Bankruptcy; Appointment of 
                           Receiver, etc..................................... 46
                  (H)      Voluntary Bankruptcy; Appointment of 
                           Receiver, etc..................................... 46
                  (I)      Liens............................................. 46
                  (J)      Judgment and Attachments.......................... 46
                  (K)      Dissolution....................................... 47
                  (L)      Solvency.......................................... 47
                  (M)      Injunction........................................ 47

                                        v


                  (N)      Invalidity of Loan Documents...................... 47
                  (O)      Failure of Security............................... 47
                  (P)      Damage, Strike, Casualty.......................... 47
                  (Q)      Licenses and Permits.............................. 47
                  (R)      Forfeiture........................................ 47
         8.2      Suspension of Commitments.................................. 48
         8.3      Acceleration............................................... 48
         8.4      Remedies................................................... 48
         8.5      Appointment of Attorney-in-Fact............................ 49
         8.6      Limitation on Duty of Lender with Respect to Collateral.... 49
         8.7      Application of Proceeds.................................... 49
         8.8      License of Intellectual Property........................... 50
         8.9      Canadian Remedies.......................................... 50
         8.10     Waivers, Non-Exclusive Remedies............................ 52
         8.11     Judgment................................................... 52

         SECTION 9  MISCELLANEOUS

         9.1      Assignments and Participations..............................53
         9.2      Set Off.................................................... 53
         9.3      Expenses and Attorneys' Fees............................... 53
         9.4      Indemnity.................................................. 54
         9.5      Amendments and Waivers..................................... 55
         9.6      Notices.................................................... 55
         9.7      Survival of Warranties and Certain Agreements.............. 56
         9.8      Indulgence Not Waiver...................................... 56
         9.9      Marshaling; Payments Set Aside............................. 56
         9.10     Entire Agreement........................................... 56
         9.11     Independence of Covenants.................................. 56
         9.12     Severability............................................... 56
         9.13     Headings................................................... 57
         9.14     APPLICABLE LAW............................................. 57
         9.15     Successors and Assigns..................................... 57
         9.16     No Fiduciary Relationship; Limitation of Liabilities....... 57
         9.17     CONSENT TO JURISDICTION.................................... 57
         9.18     WAIVER OF JURY TRIAL....................................... 58
         9.19     Construction............................................... 58
         9.20     Counterparts; Effectiveness................................ 58
         9.21     No Duty.................................................... 58
         9.22     Confidentiality............................................ 58

                                           vi




                                    EXHIBITS

A                 Borrowing Base Certificate
B                 Compliance Certificate


                                    SCHEDULES

1.1(A)   Other Liens
1.1(B)   Pro Forma
3.1(A)   List of Closing Documents
4.1(B)   Capitalization of Loan Parties
4.6               Trade Names (Present and Past Five Years)
4.7               Location of Principal Place of Business, Books
                  and Records and Collateral
4.13              Intellectual Property
4.14              Brokers Fees
4.20              Bank Accounts
4.21              Subsidiaries
4.22              Employee Matters
7.1               Existing Indebtedness

                                               vii






                                    EXHIBIT B

                        [FORM OF COMPLIANCE CERTIFICATE]

                                              _________________, 19___

Heller Business Credit
500 West Monroe Street
Chicago, Illinois  60661

         Re:      Compliance Certificate for EDITEK and Subsidiaries

Ladies and Gentlemen:

         This certificate is given in accordance with subsection  5.1(E) of that
certain Loan and Security Agreement dated as of January ___, 1996 by and between
EDITEK,  Inc.,  Psychiatric   Diagnostic   Laboratories  of  America,  Inc.  and
DiAgnostix,  Inc.  ("Borrowers") and Heller Financial,  Inc. (as the same may be
amended,  supplemented  or  otherwise  modified  from  time to time,  the  "Loan
Agreement").  Capitalized  terms used herein without  definition  shall have the
meanings assigned to such terms in the Loan Agreement. I hereby certify that:

         (a)      I am the [Chief Executive Officer] [Chief  Financial  Officer]
                  of Editek;

         (b)      The enclosed  consolidated and  consolidating  balance sheets,
                  income  statements  and cash flow  statements of Borrowers and
                  their respective  Subsidiaries fairly present the consolidated
                  and consolidating  financial  condition of Borrowers and their
                  respective Subsidiaries as of the dates indicated,  and I have
                  reviewed such statements in preparing this certificate;

         (c)      I have reviewed the terms of the Loan Agreement and have made,
                  or  caused  to be made  under  my  supervision,  a  review  in
                  reasonable detail of the transactions and financial  condition
                  of  Borrowers  during  the  accounting  period  covered by the
                  enclosed financial statements;

         (d)      The  examination  in paragraph (c) did not disclose and I have
                  no knowledge of the  existence of any  condition or event that
                  constitutes a Default or an Event of Default as of the date of
                  this certificate except as set forth below.

                  Described below (or in a separate  attachment  hereto) are the
                  exceptions,  if any, to paragraph (d), listing in detail,  the
                  nature  of   the   condition  or  event,   the  period  during
 
                  which it has existed and the  action  which   Borrowers   have
                  taken,  are taking or propose to  take  with  respect  to each
                  such  condition or event:

                  _____________________________________________________________
                  _____________________________________________________________
                  _____________________________________________________________



         (e)      Except as disclosed in paragraph  (d) above,  Borrowers are in
                  compliance with the financial covenants contained in Section 6
                  of the Loan Agreement,  as detailed in the worksheet  attached
                  as Schedule I.

         The foregoing  certifications  and the financial  statements  delivered
with this Certificate in support hereof are made and delivered this _____ day of
_____________, 19___.

                                                     Name:
                                                     Title:




                                   SCHEDULE I

                          COVENANT COMPLIANCE WORKSHEET

Based upon financial statements dated: _________________________, 19___


1.     TANGIBLE NET WORTH (ss.6.1)

       (A)    Net Worth                                                 $

less   (B)   Intangible Assets (including patents,                      $
             trademarks and trade names)

plus   (C)   Patents, Trademarks and Trade Names                        $
             (up to $2,000,000)

less   (D)   prepaid expenses                                           $

less   (E)   Affiliate obligations                                      $

less   (F)   loans to officers, stockholders

                   or employees                                         $

TANGIBLE NET WORTH (A - B - C - D - E)                                  $

Required TANGIBLE NET WORTH                                             $

                           COMPLIANCE

                         YES          NO

2.      EBITDA (ss.6.2) - Editek and diAGnostix

       (A)    net income                                                $

plus   (B)   to the extent included in the calculation of net           $
             income, income and franchise taxes paid or accrued

plus   (C)   to the extent included in the calculation of net           $
             income, Interest Expense, net of interest
             income, paid or accrued





plus   (D)   to the extent included in the calculation of net           $
             income, amortization and depreciation

plus   (E)   to the extent included in the calculation of net           $
             income, other non-cash charges (excluding
             accruals for cash expenses made in the ordinary
             course of business)

less   (F)   to the extent included in the calculation of net           $
             income, the income of any Person in which
             a Borrower has an ownership interest unless such
             income is received by a Borrower in a cash distribution

less   (G)   to the extent included in the calculation of net           $
             income, gains or losses from sales or other dispositions
             of assets, other than gains or losses from sales
             or other dispositions of Inventories in the normal
             course of business

less   (H)   to the extent included in the calculation of net           $
             income, other extraordinary or non-recurring
             gains, but not net of extraordinary or
             non-recurring "cash" losses

EBITDA (A + B + C + D + E - F - G - H)                                  $

less   Registration Payments                                            $

=      EBITDA - Registration Payments                                   $

Required EBITDA - Registration Payments                                 $


                                COMPLIANCE

                             YES          NO

3.      EBITDA (ss.6.2) - PDLA

       (A)    net income                                                $

plus   (B)   to the extent included in the calculation of net           $



             income, income and franchise taxes paid or accrued

plus   (C)   to the extent included in the calculation of net           $
             income, Interest Expense, net of interest
             income, paid or accrued

plus   (D)   to the extent included in the calculation of net           $
             income, amortization and depreciation

plus   (E)   to the extent included in the calculation of net           $
             income, other non-cash charges (excluding
             accruals for cash expenses made in the ordinary
             course of business)

less   (F)   to the extent included in the calculation of net           $
             income, the income of any Person in which
             a Borrower has an ownership interest unless such
             income is received by a Borrower in a cash distribution

less   (G)   to the extent included in the calculation of net           $
             income, gains or losses from sales or other dispositions
             of assets, other than gains or losses from sales
             or other dispositions of Inventories in the normal
             course of business

less   (H)   to the extent included in the calculation of net           $
             income, other extraordinary or non-recurring
             gains, but not net of extraordinary or
             non-recurring "cash" losses

EBITDA (A + B + C + D + E - F - G - H)                                  $

less   Registration Payments                                            $

=      EBITDA - Registration Payments                                   $

Required EBITDA - Registration Payments                                 $


                                 COMPLIANCE

                               YES          NO




4.      EBITDA (ss.6.2) - Consolidated

       (A)    net income                                                $

plus   (B)   to the extent included in the calculation of net           $
             income, income and franchise taxes paid or accrued

plus   (C)   to the extent included in the calculation of net           $
             income, Interest Expense, net of interest
             income, paid or accrued

plus   (D)   to the extent included in the calculation of net           $
             income, amortization and depreciation

plus   (E)   to the extent included in the calculation of net           $
             income, other non-cash charges (excluding
             accruals for cash expenses made in the ordinary
             course of business)

less   (F)   to the extent included in the calculation of net           $      
             income, the income of any Person in which
             a Borrower has an ownership interest unless such
             income is received by a Borrower in a cash distribution

less   (G)   to the extent included in the calculation of net           $
             income, gains or losses from sales or other dispositions
             of assets, other than gains or losses from sales
             or other dispositions of Inventories in the normal
             course of business

less   (H)   to the extent included in the calculation of net           $
             income, other extraordinary or non-recurring
             gains, but not net of extraordinary or
             non-recurring "cash" losses

EBITDA (A + B + C + D + E - F - G - H)                                  $

less   Registration Payments                                            $

=      EBITDA - Registration Payments                                   $

Required EBITDA - Registration Payments                                 $



                                COMPLIANCE

                              YES          NO

     5.    RATIO OF INDEBTEDNESS TO TANGIBLE NET WORTH (ss.6.3)

             (A) Indebtedness                                           $

             (B) Tangible Net Worth                                     $

INDEBTEDNESS TO TANGIBLE NET WORTH (A / B :1)

Required INDEBTEDNESS TO TANGIBLE NET WORTH

                           COMPLIANCE

                         YES          NO

     6.    CAPITAL EXPENDITURES (ss.6.5)

     Capital   Expenditures   (excluding   trade-ins   and   excluding   Capital
     Expenditures  in respect of  replacement  assets to the extent  funded with
     casualty insurance proceeds)

     for Fiscal Year ended _______________, 19___                       $


CAPITAL EXPENDITURE Limit:                                              $

                          COMPLIANCE

                       YES          NO

5.     FIXED CHARGE COVERAGE (ss.6.6)


       (A)    Sum of:

             (i)    EBITDA for Period                                   $



       less  (ii)  Capital Expenditures                                 $

       less  (iii) Registration Payments                                $       

       =   Operating Cash Flow                                          $

       (B)    Fixed Charges for Period                                  $

FIXED CHARGE COVERAGE (A / B)

Required FIXED CHARGE COVERAGE

                         COMPLIANCE

                       YES          NO

5.     INTEREST COVERAGE (ss.6.7)

       (C)    Sum of:

             (i)    EBITDA for Period                                   $

       less  (ii)  Capital Expenditures                                 $

       less  (iii) Registration Payments                                $

       =   Operating Cash Flow                                          $

       (D)    Interest Expenses for Period                              $

INTEREST COVERAGE (A / B)

Required INTEREST COVERAGE

                              COMPLIANCE

                           YES          NO



                                         Schedule 1.1(A)

                                         Permitted Liens


Debtor              Secured Party                 Jurisdiction       Collateral
MedTox              Hewlett-Packard               Minnesota          See item 1
MedTox              Hewlett-Packard               Minnesota          See item 2
MedTox              Hewlett-Packard               Minnesota          See item 3
MedTox              Hewlett-Packard               Minnesota          See item 6
MedTox              SYVA Co.                      Minnesota          See item 7
MedTox              SYVA Co.                      Minnesota          See item 8
MedTox              Hewlett-Packard               Minnesota          See item 9
Psychiatric         First Wisconsin National      New Jersey         See item 12
Diagnostic          Bank of Milwaukee
Laboratories        First Wisconsin National      New Jersey         See item 13
Princeton           Bank of Milwaukee
Diagnostic
Laboratories
Editek              Graybar Financial Services    Alamance           See item 14
                                                  County      
Psychiatric         SYVA Co.                      New Jersey         See item 20
Diagnostic Lab
Psychiatric         SYVA Co.                      New Jersey         See item 21
Diagnostic Lab
Editek              Graybar Financial Services    North Carolina     See item 26




                                         Schedule 1.1(B)

                                            Pro Forma


               Attached is a copy of the unaudited consolidated balance sheet
               of Borrowers after giving effect to the MedTox Acquisition.





                                         Schedule 3.1(A)

                                    List of Closing Documents



                                         Schedule 4.1(B)


I.     Capitalization of Borrowers and Affiliates


A.     Editek, Inc.

       The authorized capital stock of Editek, Inc. consists of
       31,000,000 shares of which 30,000,000 are designated common
       stock, $0.15 par value and 1,000,000 are designated preferred
       stock, $1.00 par value.  As of the Closing, 10,440,083 shares of
       common stock and 240 shares of preferred stock are outstanding.


B.     diAGnostix, Inc.

       The authorized capital stock of diAGnostix, Inc. consists of
       7,500,000 shares of common stock, $0.01 par value, of which 1,000
       shares are issued and outstanding and are owned by Editek, Inc.


C.     Princeton Diagnostic Laboratories of America, Inc.

       The authorized capital stock of Princeton Diagnostic Laboratories
       of America, Inc. consists of 7,500,000 shares of common stock,
       $0.01 par value, of which 500 shares are issued and outstanding
       and are owned by Editek, Inc.


D.     Psychiatric Diagnostic Laboratories of America, Inc.

       The authorized capital stock of Psychiatric Diagnostic
       Laboratories of America, Inc. consists of 256,000 shares of which
       250,000 shares are designated common stock, $0.004 par value and
       6,000 shares are designated preferred stock, no par value.  As of
       the closing, 500 shares of common stock are issued and
       outstanding and are owned by Princeton Diagnostic Laboratories of
       America, Inc.  No shares of preferred stock are outstanding.


E.     National Consortium For A Drug-Free Workplace, Inc.

       The authorized capital stock of National Consortium For A
       Drug-Free Workplace, Inc. consists of 100 shares of common stock,
       $0.01 par value, of which 50 shares are issued and outstanding
       and are owned by Princeton Diagnostics Laboratories of America,
       Inc.


II.    Outstanding Conversion Rights, Options, Warrants for Purchase of
       Capital Stock of Borrowers and Affiliates

A.     EDITEK, Inc.

       Outstanding options to purchase an aggregate of 449,406 shares of
       Common Stock pursuant to awards under the EDITEK, Inc. 1983
       Incentive Stock Option Plan.

       Outstanding options to purchase an aggregate of 47,864 shares of
       Common Stock pursuant to awards under the EDITEK, Inc. Amended
       and Restated Stock Option Plan for Non-Employee Directors.

       Outstanding option to purchase 7,760 shares of Common Stock
       pursuant to Stock Option Agreement dated January 14, 1993 between
       EDITEK, Inc. and Mark D. Dibner.

       Outstanding subscriptions to purchase an aggregate of 5,446
       shares of Common Stock pursuant to awards under the EDITEK, Inc.
       Qualified Employee Stock Purchase Plan.

       Outstanding options to purchase an aggregate of 33,333 shares of
       Common Stock pursuant to nonqualified stock option agreements
       between EDITEK, Inc. and James D. Skinner.

       Outstanding options to purchase an aggregate of 721,289 shares of
       Common Stock pursuant to awards under the EDITEK, Inc. Amended
       and Restated Equity Compensation Plan.

       Stock Purchase Warrants to purchase an aggregate of 473,229
       shares of Common Stock.

B.     diAGnostix, Inc.

       None.

C.     Princeton Diagnostic Laboratories of America, Inc.

       None.

D.     Psychiatric Diagnostic Laboratories of America, Inc.

       None.

E.     National Consortium For A Drug-Free Workplace, Inc.

       None.


                                          Schedule 4.6


                            Trade Names (Present and Past Five Years)


                                              NONE



                                          Schedule 4.7

                         Location of Principal Place of Business, Books
                                   and Records and Collateral


A.     Editek, Inc.

       Corporate headquarters, research and development, operations and
       administrative functions are located in the NOVA building at 1238
       Anthony Road, Burlington, North Carolina 27215.

       Editek also leases laboratory space and land for its Granite Hall
       Laboratory Animal Facility in Warrenton, North Carolina.  The
       address for the facility is Route 1, Box 110-S, Warrenton, North
       Carolina 27589.

B.     Princeton Diagnostic Laboratories of America, Inc.

       Corporate headquarters are located at the NOVA building at 1238
       Anthony Road, Burlington, North Carolina 27215.

C.     Psychiatric Diagnostic Laboratories of America, Inc.

       Laboratory testing facility including administrative functions
       are located at 100 Corporate Court, South Plainfield, New Jersey
       07080.

       The leases assumed by Psychiatric Diagnostic Laboratories of
       America, Inc., pursuant to the MedTox acquisition are as follows:

       Location                                         Description

       402 West County Road D                     Primary laboratory location
       St. Paul, Minnesota  55112                 and administrative
                                                  offices

       8600 West Catalpa Avenue                   Facility empty
       Chicago, Illinois  60656

       109 West Dudleytown Road                   Service center, local client
       Bloomfield, Connecticut  06002             service and courier service

       6160 Variel Avenue                         Subleased premises to
       Woodland Hills, California  91367          TOXWORX Laboratories


                                          Schedule 4.7
                                           (continued)



D.     diAGnostix, Inc.

       Warehouse and administrative functions located at 5730 Coopers
       Avenue, Unit #27, Mississauga, Ontario Canada L4Z 2E9.


E.     National Consortium For A Drug-Free Workplace, Inc.

       Administrative facilities located at 100 Corporate Court, South
       Plainfield, New Jersey 07080.




                                          Schedule 4.13

                                      Intellectual Property


A.     The following patents are owned by Editek.  The other Borrowers
do not own any patents.

                                                  Patent
Jurisdiction    Patent Name                       Number      Issue Date

U.S.          Rapid Radioimmunoassay              4,399,229    08/16/83
              Product and Method of Making
              and Using Same
U.S.          Rotary Fluid Manipulator            4,938,927    07/03/90
U.S.          Rotary Fluid Manipulator            5,141,875    08/25/92
U.S.          Test Kit For Determining The        4,900,663    02/13/90
              Presence of Organic Materials
              and Method of Utilizing Same
U.S.          Test Kit For Determining The        5,240,844    08/31/93
              Presence of Organic Materials
              and Method of Utilizing Same
U.S.          Suspension Liquid Separator         4,696,797    09/29/87
U.S.          Multi-Layered Test Card For         5,202,268    04/13/93
              The Determination of Substances
              In Liquids
U.S.          Devise For Analysis For             5,435,970    07/25/95
              Constituents In Biological Fluids
U.S.          Animal Cage and Method              4,593,650    06/10/86
U.S.          Method For Preserving Plated        4,709,819    12/01/87
              Media and Products
Australia     Test Kit - Original                   594,942    09/13/85
Australia     Test Kit - Bi-Directional Flow        608,956    03/14/88
              Continuation
Australia     Suspension Liquid Separator           586,849    04/15/85
Belgium       Test Kit - Original                   904,484    03/25/86




                                                   Patent
Jurisdiction     Patent Name                       Number      Issue Date
Belgium          Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
Belgium          Suspension Liquid Separator       Pending     Pending
Canada           Test Kit - Original               1,258,626   08/22/89
Canada           Test Kit - Bi-Directional Flow    Pending     Pending
                 Continuation
Canada           Suspension Liquid Separator       1,271,709   07/17/90
Canada           Multi-Layered Test Card           Pending     Pending
France           Test Kit - Original               2,587,488   04/03/86
France           Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
France           Suspension Liquid Separator       904,484     03/25/86
France           Multi-Layered Test Card           Pending     Pending
Germany          Test Kit - Original               3,606,124   02/26/86
Germany          Test Kit - Bi-Directional Flow    689 19 103  03/13/89
                 Continuation
Germany          Suspension Liquid Separator       Pending     Pending
Germany          Multi-Layered Test Card           Pending     Pending
G. Britain       Test Kit - Original               2,180,645   12/28/89
G. Britain       Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
G. Britain       Suspension Liquid Separator       2,181,662   06/21/89
G. Britain       Multi-Layered Test Card           Pending     Pending
Holland          Test Kit - Original               Pending     Pending
Holland          Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
Holland          Suspension Liquid Separator       Pending     Pending
Holland          Multi-Layered Test Card           Pending     Pending
Italy            Test Kit - Original               1,190,191   02/16/88


                                                   Patent
Jurisdiction       Patent Name                     Number      Issue Date
Italy            Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
Italy            Suspension Liquid Separator       1,190,204   02/16/88
Italy            Multi-Layered Test Card           Pending     Pending
Japan            Test Kit - Original               Pending     Pending
Japan            Test Kit - Bi-Directional Flow    Pending     Pending
                 Continuation
Japan            Suspension Liquid Separator       1916522     03/23/95
Japan            Multi-Layered Test Card           Pending     Pending
Sweden           Test Kit - Original               86,004,546  04/08/93
Sweden           Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
Sweden           Suspension Liquid Separator       86,000,197  04/15/85
Sweden           Multi-Layered Test Card           Pending     Pending
Switzerland      Test Kit - Original               671,467     02/27/86
Switzerland      Test Kit - Bi-Directional Flow    0 333 286   03/13/89
                 Continuation
Switzerland      Suspension Liquid Separator       671,343     02/15/86
Luxembourg       Multi-Layered Test Card           Pending     Pending




                                          Schedule 4.13
                                           (continued)



B.     The following trademarks are owned by Editek:


Trade Mark             Registration Number            Registration Date
EDITEK                     1,879,044                       02/14/95
BIOMAN                       363,506                       11/10/89
LOGO                       1,374,423                       12/10/85
QUIK-CARD                  1,387,168                       03/25/86
EZ-SCREEN                  1,412,788                       10/14/86
DAIRISCREEN                1,629,710                       01/01/91
DAIRYSCREEN                1,629,709                       01/01/91
VERDICT                    1,771,281                       05/18/93
PREDICT                    1,877,141                       01/31/95
RECON                      1,847,306                       07/26/94
EZ-QUANT                   1,917,508                       09/12/95

B.     The following trademarks are owned by Princeton.

Trade Mark             Registration Number            Registration Date
PDLA                       1,477,191                       02/16/88

C.     The following trademarks are owned by PDLA.  The other Borrowers
       do not own any trademarks.

Trade Mark             Registration Number            Registration Date
MEDTOX                     1,542,034                      05/30/89


                                          Schedule 4.14

                                          Broker's Fees


Pursuant to the issuance of the Convertible Preferred Stock, Shoreline
Pacific, The Institutional Division of Financial West Group, will be
paid 6% of the gross proceeds in cash and will be issued warrants to
purchase shares of common stock of Editek, Inc., having a fair market
value and aggregate exercise price equal to 8% of the gross proceeds.

Interstate Johnson Lane will be paid a commission of $122,000 at the closing.





                                          Schedule 4.20

                                          Bank Accounts



Psychiatric Diagnostic Laboratories of America, Inc.

First Fidelity - New Jersey

Account Number:  508-006533-1 (operating account)
Account Number:  508-005627-1 (payroll account)
Account Number:  3000397418 (blocked account)

Norwest - M.N.

Account Number:  3973656691 (operating account)
Account Number:  3973656552 (payroll account)
Account Number:  3973656616 (blocked account)


Editek, Inc.

First Union National Bank of N.C.

Account Number:       2000000009889 (payroll account)
Account Number:       2000000009892 (operating account)
Account Number:       2000000706674 (money market account)
Account Number:       2000000706645 (flexible benefits account)
Account Number:       2000000034825 (401(k) account)
Account Number:       2000000734905 (blocked account)


diAGnostix, Inc.

The Toronto-Dominion Bank

Account Number:       0566 7302749 (operating account)
Account Number:       0566 0314541 (payroll account)



Princeton Diagnostic Laboratories of America, Inc. and National
Consortium For A Drug- Free Workplace, Inc. do not have any bank
accounts.


                                          Schedule 4.21

                                          Subsidiaries



Editek, Inc. owns all of the issued and outstanding stock of: (i)
Princeton Diagnostic Laboratories of America, Inc., a Delaware
corporation; and (ii) diAGnostix, Inc., a Delaware corporation.

Princeton Diagnostic Laboratories of America, Inc., in turn, owns all of
the issued and outstanding stock of: (i) Psychiatric Diagnostic
Laboratories of America, Inc., a Delaware corporation; and (ii) National
Consortium For A Drug-Free Workplace, Inc., a Delaware corporation.
National Consortium For A Drug-Free Workplace, Inc. has no assets.


                                          Schedule 4.22

                                        Employee Matters

A.     Employment and Other Contracts

       1.      Editek, Inc.

               a.     Employment Agreement with James Skinner, dated on
                      or about January 25, 1996;

               b.     Employment Agreement with Peter Heath, dated on or
                      about January 25, 1996;

               c.     Employment Agreement with Michael Terretti, dated
                      on or about January 25, 1996; and

               d.     Severance Agreement with James S. Arrington, dated
                      on or about January 25, 1996.


       2.      Princeton Diagnostic Laboratories of America, Inc.

               NONE


       3.      Psychiatric Diagnostic Laboratories of America, Inc.

               a.     Letter dated February 15, 1995 regarding the
                      employment of Dr. Lawrence J. Felice;

               b.     Employment Agreement with Harry G. McCoy, dated on
                      or about January 25, 1996;

               c.     Employment Agreement with D. Gary Hemphill, dated
                      on or about January 25, 1996;

               d.     Employment Agreement with Jennifer S. Collins,
                      dated on or about January 25, 1996;

               e.     Employment Agreement with Jacquelyn L. Heytens,
                      dated January 25, 1996;

               f.     Employment Agreement with Susan E. Puskas, dated
                      on or about January 25, 1996;

               g.     Employment Agreement with Barbara S. Mayer, dated
                      on or about January 25, 1996; and
 

                                          Schedule 4.22
                                           (continued)

               h.     Employment Agreement with Gregory A. Lowery, dated
                      on or about January 25, 1996.


       4.      diAGnostix, Inc.

               NONE


       5.      National Consortium For A Drug-Free Workplace, Inc.

               NONE


                                          Schedule 7.1

                                      Existing Indebtedness




                                                     
Editek, Inc.

North Carolina Biotechnology                              $ 62,834.75
Center (NCBC) Promissory Note
due August 15, 1996

Novamann International, Final                               14,497.85
payment due for purchase of
Bioman Products, Inc.

Dr. Samuel C. Powell, 90 Day                               100,000.00
Note due March 17, 1996
(Unsecured loan made by Dr.
Powell to provide operating funds
prior to recently completed private
placement)

First Union National Bank of NC,                            15,700.00    (est)
Promissory Note secured by
1996 Ford Pickup Truck, Serial #
1FTEF15Y3TLA11649
                                                          $193,032.60



Psychiatric Diagnostic Laboratories of America, Inc.

Norwest Loan #031597                                      $407,853.27 (to be paid at 1/29/96 closing)
Norwest Loan #033095                                       437,463.95 (to be paid at 1/29/96 closing)
Norwest Equipment Loans                                    368,906.20 (to be paid at 1/29/96 closing)

                                                        $1,214,223.42
                                                           __________

                                                        $1,407,256.02



                                          Schedule 7.1
                                           (continued)



Princeton Diagnostic Laboratories of America, Inc.

NONE

diAGnostix, Inc.

NONE

National Consortium For A Drug Free Work Place, Inc.

NONE