Serial Number [           ]
                                                     ---------------------------

         Void after 5:00 p.m., New York Time, on May 15, 2001(unless extended as
provided below)

                                                     Option to Purchase certain
                                                     Shares of Common Stock,
                                                     dated May 16, 1996.

                                 CERTIFICATE OF
                         OPTION TO PURCHASE COMMON STOCK
                                       OF
                            CHEUNG LABORATORIES, INC.

This Is To Certify That,  FOR VALUE  RECEIVED,  _______________________________,
his/her  nominees,  or assigns  (hereinafter,  the  "Holder(s)") are entitled to
purchase, subject to the provisions of this Option (its successors, divisions or
additions),  from Cheung  Laboratories,  Inc., a corporation duly organized,  in
good standing  within its domicile,  and whose offices as of the date hereof are
at 10220-I Old Columbia Road, Columbia,  MD 21046 (hereinafter,  the "Company"),
________________________________(  )shares of  restricted  and  legended  common
stock of the Company  ("Common  Stock") at a purchase price (the "Stock Purchase
Price") equal to Thirty Five Cents ($00.35 U.S.)per share in such amounts and at
such times as are provided herein.  The Stock Purchase Price and, in some cases,
the number of shares purchasable hereunder are subject to adjustment as provided
in Section 3 of this  Option.  This Option shall be  exercisable  in whole or in
part at any time after May 16, 1996 (the " Commencement Date"),  unless extended
in  accordance  with Section 9, not later than 5:00 P.M.  (New York Time) on the
Expiration  Date (as  defined  below),  upon  surrender  to the  Company  at its
principle office at 10220-I Old Columbia Road,  Columbia,  Maryland  21046-1705,
Attention:  Chairman of the Board of Directors (or at such other location as the
Company may advise  Holder(s) in writing) of this Option properly  endorsed with
the form of Subscription Agreement attached hereto duly filled in and signed and
upon payment in cash or cashier's  check of the aggregate  Stock  Purchase Price
for the number of shares for which this Option is being exercised  determined in
accordance  with the  provisions  hereof.  Unless  extended in  accordance  with
Section 9, this Option and all rights hereunder,  to the extent not exercised in
the manner set forth  herein  shall  terminate  and become  null and void on the
Expiration  Date."Expiration  Date" means 5:00 P.M. (New York Time) on the fifth
anniversary of the  Commencement  Date. In the event that the Holder(s) does not
exercise  this  Option  pursuant to the terms of this  Option,  then this Option
shall expire, be canceled, and be null and void.

         This Option is subject to the following terms and conditions:

         1. Exercise:  Issuance of Certificates;  Payment for Shares; Conversion
            Right.
            --------------------------------------------------------------------

                  1.1 Duration of Exercise of Option. This Option is exercisable
         at the option of the  Holder(s)  at any time or from time to time after
         the  Commencement  Date but not later than 5:00 P.M. (New York Time) on
         the Expiration  Date(unless extended in accordance with Section 9), for
         all  or a  portion  of the  shares  of  Stock  which  may be  purchased
         hereunder.  The Company agrees that the shares of Stock purchased under
         this Option  shall be and are deemed to be issued to  Holder(s)  as the
         record  owner of such  shares at the close of  business  on the date on
         which this Option shall have been surrendered and payment made for such
         shares.  Subject to the provisions of Section 2,  certificates  for the
         shares of Stock so  purchased,  together  with any other  securities or
         property to which  Holder(s) is entitled upon such  exercise,  shall be
         delivered  to  Holder(s)  by the Company or its  transfer  agent at the
         Company's expense within a reasonable time after the rights represented
         by this Option have been exercised. Each stock certificate so delivered
         shall  be in  such  denominations  of  Stock  as  may be  requested  by


                                       1


         Holder(s)  and shall be  registered  in the name of  Holder(s)  or such
         other name as shall be designated  by  Holder(s).  If, upon exercise of
         this  Option,  fewer than all of the shares of Stock  evidenced by this
         Option are purchased prior to the Expiration  Date of this Option,  one
         or more new options  substantially in the form of, and on the terms in,
         this Option will be issued for the remaining  number of shares of Stock
         not purchased upon exercise of this Option.

         2.  Shares  to Be  Fully  Paid:  Reservation  of  Shares.  The  Company
covenants  and  agrees  that all  shares of Stock  which may be issued  upon the
exercise of this Option (the "Option  Shares")  shall,  upon  issuance,  be duly
authorized,  validly  issued,  fully  paid and  nonassessable  and free from all
preemptive  rights of any stockholder and free of all taxes,  liens, and charges
with respect to the issuance thereof.  The Company will take all such reasonable
actions as may be necessary to assure that such shares of Stock may be issued as
provided herein without violation of any applicable law or regulation, or of any
requirements of any domestic  securities  exchange or automated quotation system
upon which the Stock may be listed.

         3.  Adjustment of Stock Purchase Price and Number of Shares.  The Stock
Purchase  Price and, in some cases,  the number of shares  purchasable  upon the
exercise of this Option  shall be subject to  adjustment  from time to time upon
the occurrence of certain events described in this Section 3.

                  3.1 Split or Combination of Stock and Stock Dividend:  In case
         the Company shall at any time subdivide its outstanding shares of Stock
         into a greater  number of shares or declare a  dividend  upon its Stock
         payable  solely in shares of Stock,  the Stock Purchase Price in effect
         immediately   prior  to  such  subdivision  or  declaration   shall  be
         proportionally reduced, and the number of shares issuable upon exercise
         of the Option shall be proportionately  increased.  Conversely, in case
         the outstanding shares of Stock of the Company shall be combined into a
         smaller  number of shares (such as a reverse  stock  split,  but not to
         include the anticipated  redemption of 20,000,000  shares of stock from
         Mr. Gao Yu Wen) the Stock Purchase Price in effect immediately prior to
         such combination shall be proportionately  increased, and the number of
         shares  issuable upon  exercise of the Option shall be  proportionately
         reduced.

                  3.2  Dilutive  Issuances.   If  prior  to  completion  of  the
         Company's Next Public Offering,  the Company shall sell or issue at any
         time  after  the  Commencement  Date of this  Option  and  prior to its
         termination,  shares of Common Stock at a consideration  per share less
         than $00.35,  or convertible  securities with conversion rate less than
         $00.35 per share,  or Warrants or Options  with strike  price less than
         $00.35 per share, then, upon such sale or issuance,  the Stock Purchase
         Price shall be reduced to the lowest of the above.


                  3.3 Notice of  Adjustment.  Promptly  after  adjustment of the
         Stock  Purchase  Price or any  increase  or  decrease  in the number of
         shares  purchasable upon the exercise of this Option, the Company shall
         give written notice  thereof,  by first-class  mail,  postage  prepaid,
         addressed to the registered  Holder(s) of this Option at the address of
         such  Holder(s) as shown on the books of the Company.  The notice shall
         be signed by the  Company's  President or Chief  Executive  Officer and
         shall state the effective date of the adjustment and the Stock Purchase
         Price resulting from such  adjustment and the increase or decrease,  if
         any,  in the  number  of  shares  purchasable  at such  price  upon the
         exercise of this Option,  setting forth in reasonable detail the method
         of calculation and the facts upon which such calculation is based.

                  3.4      Notices.  If at any time:
                           -------

                           3.4.1 the Company  shall  declare  any cash  dividend
                  upon its Stock;

                           3.4.2 the Company shall declare any dividend upon its
                  Stock payable in stock (other than a dividend  payable  solely
                  in  shares of Stock)  or make any  special  dividend  or other
                  distribution to the Holder of its Stock;


                                        2



                           3.4.3 there shall be any  consolidation  or merger of
                  the  Company  with  another  corporation,  or a sale of all or
                  substantially   all  of  the   Company's   assets  to  another
                  corporation; or

                           3.4.4  there  shall  be a  voluntary  or  involuntary
                  dissolution, liquidation or winding-up of the Company

         then,  in any one or more of said  cases,  the Company  shall give,  by
         certified  or  registered  mail,  postage  prepaid,  addressed  to  the
         registered Holder(s) of this Option at the address of such Holder(s) as
         shown on the books of the Company,  (i) at least 30 days prior  written
         notice of the date on which the books of the  Company  shall close or a
         record shall be taken for such dividend,  distribution  or subscription
         rights  or for  determining  rights  to vote  in  respect  of any  such
         dissolution,  liquidation  or  winding-up;  (ii) at least 10 days prior
         written  notice  of the date on which the  books of the  Company  shall
         close or a record  shall be taken  for  determining  rights  to vote in
         respect of any such  reorganization,  reclassification,  consolidation,
         merger  or sale,  and  (iii)  in the  case of any such  reorganization,
         reclassification, consolidation, merger, sale, dissolution, liquidation
         or  winding-up,  at least 30 days  written  notice of the date when the
         same shall take place.  Any notice given in accordance  with clause (i)
         above  shall  also  specify,   in  the  case  of  any  such   dividend,
         distribution  or option  rights,  the date on which the Holder of Stock
         shall be entitled  thereto.  Any notice given in accordance with clause
         (iii) above shall also specify the date on which the Holder(s) of Stock
         shall be  entitled  to exchange  their  Stock for  securities  or other
         property  deliverable  upon  such   reorganization,   reclassification,
         consolidation, merger, sale, dissolution, liquidation or winding-up, as
         the case may be. If the  Holder(s) of the Option does not exercise this
         Option prior to the occurrence of an event described  above,  except as
         provided in Sections 3.1 and 3.5, the  Holder(s)  shall not be entitled
         to receive the  benefits  accruing to existing  holders of the Stock in
         such event.  Notwithstanding anything herein to the contrary, if and to
         the extent the  Holder(s)  chooses to exercise  this Option  within the
         10-day period following  receipt of the notice specified in clause (ii)
         above,  the  Holder(s) may elect to pay the  aggregate  Stock  Purchase
         Price by  delivering  to the Company  cash or a cashier's  check in the
         amount  of the  aggregate  par  value  of the  shares  of  Stock  to be
         purchased and the Holder's full recourse  Promissory Note in the amount
         of the balance of the aggregate Stock Purchase Price,  which Note shall
         be payable to the order of the  Company in a single sum on the 30th day
         following the date of receipt of such notice and shall bear interest at
         the  lowest   applicable   federal   short-term   rate  (using  monthly
         compounding) as established pursuant to Section 1274(d) of the Internal
         Revenue Code of 1986, as amended, or any successor provision; provided,
         however, that if the Holder(s) elects to deliver such a Promissory Note
         to the  Company,  the  Holder(s)  will  pledge to the Company all Stock
         issued in connection with the exercise of this Option,  and the Company
         shall retain  possession  of the  certificates  evidencing  such Stock,
         until such time as the Note is paid in full.

                  3.5  Changes  in  Stock.  In case at any  time  following  the
         Commencement  Date  hereof,  the  Company  shall  be  a  party  to  any
         transaction (including,  without limitation,  a merger,  consolidation,
         sale  of  all  or   substantially   all  of  the  Company's  assets  or
         recapitalization  of the  Stock)  in which the  previously  outstanding
         Stock shall be changed into or exchanged  for  different  securities of
         the Company or common stock or other securities of another  corporation
         or  interests in a  noncorporate  entity or other  property  (including
         cash) or any combination of any of the foregoing (each such transaction
         being herein called the  "Transaction"  and the date of consummation of
         the Transaction being herein called the "Consummation Date"), then as a
         condition of the consummation of the  Transaction,  lawful and adequate
         provisions shall be made so that each Holder,  upon the exercise hereof
         on or before the Consummation  Date, shall be entitled to receive,  and
         this Option shall thereafter represent the right to receive, in lieu of
         the Stock issuable upon such exercise prior to the  Consummation  Date,
         the highest amount of securities or other property to which such Holder
         would   actually  have  been   entitled  as  a  stockholder   upon  the
         consummation  of the  Transaction  if such  Holder had  exercised  such
         Option  immediately  prior thereto.  The provisions of this Section 3.5
         shall similarly apply to successive Transactions.


                                        3



         4. Issue Tax. The issuance of certificates for shares of Stock upon the
exercise of the Option  shall be made  without  charge to the  Holder(s)  of the
Option for any issue tax in respect thereof, provided, however, that the Company
shall not be  required  to pay any tax which may be  payable  in  respect of any
transfer  involved in the issuance and  delivery of any  certificates  in a name
other than that of the then Holder(s) of the Option being exercised.

         5. No Voting or  Dividend  Rights;  Limitation  of  Liability.  Nothing
contained in this Option shall be construed  as  conferring  upon the  Holder(s)
hereof the right to vote or to consent or to receive  notice as a stockholder in
respect of meetings of stockholders for the election of directors of the Company
or any other matters or any rights  whatsoever as a stockholder  of the Company.
Except for the adjustment to the Stock Purchase Price pursuant to Section 3.1 in
the event of a dividend on the Stock payable in shares of Stock, no dividends or
interest  shall be payable or accrued in respect of this Option or the  interest
represented  hereby or the shares  purchasable  hereunder until, and only to the
extent that, this Option shall have been exercised. No provisions hereof, in the
absence of affirmative  action by the Holder(s) to purchase shares of Stock, and
no mere enumeration  herein of the rights or privileges of the Holder(s) hereof,
shall give rise to any liability of such  Holder(s) for the Stock Purchase Price
or as a  stockholder  of the Company  whether such  liability is asserted by the
Company or by its creditors.

                6. Exchange, Assignment or Loss of Option. Subject to applicable
securities  laws and the terms of the legend set forth in  Section  7.2  hereof,
this Option  certificate is fully  exchangeable and (by definition)  assignable,
without expense, at the option of the Holder(s), upon presentation and surrender
hereof to the Company or at the office of its stock transfer  agent, if any, for
other Option  certificates  of different  denominations  entitling the Holder(s)
hereof to purchase in the  aggregate  the same number of shares of Common  Stock
purchasable hereunder.

Any  assignment  hereof shall be made by surrender of this Option to the Company
or at the office of its stock transfer agent,  if any, with a written,  executed
assignment,  instructions  and funds  sufficient  to pay  transfer tax (if any);
whereupon the Company shall,  without  charge,  execute and deliver a new Option
certificate  in  the  name  of the  assignee(s)  named  in  such  instrument  of
assignment and this Option  certificate shall promptly be canceled.  This Option
may be divided upon  presentation  hereof at the office of the Company or at the
office of its stock  transfer  agent,  if any,  together with a written  notice,
specifying  the names and  denominations  in which new Options are to be issued,
and signed by the Holder hereof. The terms "Option" and "Options" as used herein
include any Options issued in substitution for or replacement of this Option, or
into which this Option may be divided or exchanged.

Upon  receipt by the Company of evidence  reasonably  satisfactory  to it of the
loss, theft, destruction or mutilation of this Option, and, in the case of loss,
theft or  destruction,  of  reasonably  satisfactory  indemnification,  and upon
surrender  and  cancellation  of this  Option,  if  mutilated,  the Company will
execute and  deliver a new Option of like  tenure and date.  Any such new Option
executed and delivered shall constitute an additional  contractual obligation on
the part of the Company,  whether or not this Option so lost, stolen,  destroyed
or mutilated shall be at any time enforceable by anyone.  Nevertheless,  neither
the Company or the Holder(s) anticipate that this Option or any successor Option
shall  itself  be  registered  (rather  that  the  underlying  shares  shall  be
registered),  the Company shall not impose unreasonable burdens on the Holder(s)
with respect to indemnification if same becomes necessary.


         7.  Restrictions  on  Transferability  of Securities;  Compliance  with
             Securities Act.
             -------------------------------------------------------------------

                  7.1 Restrictions on Transferability. This Option or the Option
         Stock or any other  security  issued or issuable  upon exercise of this
         Option may not be sold,  transferred or otherwise disposed of except to
         a person who, in the opinion of counsel reasonably  satisfactory to the
         Company,  is a person to whom  this  Option  or such  Option  Stock may
         legally  be  transferred  pursuant  to this  Section  6 hereof  without
         registration and without the delivery of a current prospectus under the
         Securities Act with respect  thereto;  and then only against receipt by
         the  Company  of an  agreement  from such  person  to  comply  with the
         provisions  of this  Section  7 with  respect  to any  resale  or other
         disposition of such securities.


                                        4



                  7.2 Restrictive  Legend.  Each  certificate  representing  the
         Securities or any other securities  issued in respect of the Securities
         upon  any  stock  split,  stock  dividend,  recapitalization,   merger,
         consolidation or similar event, shall be stamped or otherwise imprinted
         with a legend  substantially  in the following form (in addition to any
         legend required under applicable state securities laws):


         THE SECURITIES  REPRESENTED  HEREBY HAVE NOT BEEN REGISTERED  UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED,  OR ANY STATE  SECURITIES  LAWS AND
         NEITHER THE SECURITIES NOR ANY INTEREST  THEREIN MAY BE OFFERED,  SOLD,
         TRANSFERRED,  PLEDGED OR  OTHERWISE  DISPOSED OF EXCEPT  PURSUANT TO AN
         EFFECTIVE  REGISTRATION  STATEMENT  UNDER  SUCH ACT OR SUCH  LAWS OR AN
         EXEMPTION FROM REGISTRATION  UNDER SUCH ACT AND SUCH LAWS WHICH, IN THE
         OPINION OF COUNSEL  FOR THE  HOLDER,  WHICH  COUNSEL  AND  OPINION  ARE
         REASONABLY SATISFACTORY TO COUNSEL FOR THIS COMPANY, IS AVAILABLE.

         8.  Registration  Rights.  The  Holder(s) of this Option shall have the
registration rights set forth as follows:

                      8.1 Demand  Registration.  If at any time,  after the Next
         Public  Offering  of  registered  Common  Shares  of  the  Company  the
         Holder(s)  shall  decide to sell or  otherwise  dispose of Option Stock
         then owned or to be owned upon intended  exercise of this Option by the
         Holder(s) , then the Holder(s)  may give written  notice to the Company
         of the proposed disposition,  specifying the number of shares of Option
         Stock to be sold or disposed of and requesting that the Company prepare
         and file a registration  statement under the Securities Act of 1933, as
         amended (the "Securities Act"), covering such Option Stock.

         The Company shall within 10 days  thereafter give written notice to the
         other Holders of Option or Option Stock of such request and each of the
         other  Holders  shall  have the  option  for a period of 30 days  after
         receipt by it (them) of notice  from the Company to include its (their)
         Option Stock in such registration statement.  The Company shall use its
         best  efforts  to  cause an  appropriate  registration  statement  (the
         "Registration  Statement")  covering such Option Stock to be filed with
         the Securities and Exchange Commission (the "Commission") and to become
         effective as soon as  reasonably  practicable  and to remain  effective
         until the  completion  of the  distribution  of the Option  Stock to be
         offered  or sold;  provided,  however,  that not more  than once in any
         twelve month period the Company  shall have the right to postpone for a
         period of up to 60 days any demand made  pursuant to this Option if the
         underwriters  for such  offering  advise the  Company  in writing  that
         market conditions make such a postponement advisable to the Company.

         The Holder(s)  whose Option Stock is (are)  included in a  Registration
         Statement   is  (are)   hereinafter   referred   to  as  the   "Selling
         Shareholder(s)".

         Each  notice  delivered  by a  Selling  Shareholder(s)  to the  Company
         pursuant to this Section 8.1 shall specify the Option Stock intended to
         be  offered  and  sold by such  Selling  Shareholder(s),  express  such
         Selling  Shareholder(s)  present intent to offer such Common Shares for
         distribution,   and   contain   the   undertaking   of   such   Selling
         Shareholder(s) to provide all information and materials and to take all
         action as may be required in order to permit the Company to comply with
         all applicable  requirements  of the Securities  Act, and any rules and
         regulations promulgated  thereunder,  and to obtain acceleration of the
         effective date of such Registration Statement.


                                        5



         The Company shall not be obligated to file more than three Registration
         Statements  pursuant to the  foregoing  provisions of this Section 8.1.
         The Company  shall bear all of the Costs and Expenses of the first such
         registration.  The  Selling  Shareholder(s)  shall  bear the  costs and
         expenses of all further  registrations  pursuant to this Section 8.1. A
         demand for  registration  under this Section 8.1 will not count as such
         until the Registration Statement has become effective.

                         8.2 Shelf  Registration By Original Holder. At any time
         and from time to time during the term of this Option or its successors,
         the original Holder(s), and only the original Holder(s) may demand (and
         actually  expects) that the Company will file a Registration  Statement
         with the Commission for the registration of underlying  shares issuable
         upon exercise of this Option or any part  thereof,  whether or not said
         Option has,  in the  interim  been  assigned  or  re-assigned  to other
         parties.

         In this event,  the Company  shall pay all of the Costs and Expenses of
         said  Registration for each such demand except that the Holder(s) shall
         be responsible, if such demand is made by the Holder(s) during a period
         in which the Company is unable or  unqualified  to file a "short  form"
         S-3 Statement (or its then relevant  equivalent)  for paying all of the
         Costs and Expenses of said  Registration  which are estimated to exceed
         costs for a similar  Registration  assuming the Company had been, as of
         the date of the  demand,  a  reporting  Company for three (3) years and
         could file a "short form" statement. In this case, the costs payable by
         the  Holder(s)  shall be  determinable  by  securities  counsel  to the
         Company and both the Company and the  Holder(s) are entitled to rely on
         such an estimate.

         Once filed,  the Company  shall be  obligated  to continue  this "shelf
         registration"  for the maximum time  allowable  under the then relevant
         regulations, at its sole expense.

                     8.3  Incidental  Registration.  Other than as  covering  in
         Section 8.2 hereof, if at any time the Company shall propose the filing
         of a Registration Statement on an appropriate form under the Securities
         Act for the registration of any securities of the Company, other than a
         registration  statement  on Form S-4 or S-8 or any  equivalent  form of
         registration  statement then in effect, then the Company shall give the
         Holder(s) notice of such proposed registration and shall include in any
         Registration  Statement relating to such securities all or a portion of
         the Option  Stock then  owned or to be owned by such  Holder(s),  which
         such Holder(s) shall request (such Holder(s) to be considered  "Selling
         Shareholder(s)"), by notice given by such Selling Shareholder(s) to the
         Company  within 15 business days after the giving of such notice by the
         Company,  to be so  included.  In the event of the  inclusion of Option
         Stock  pursuant to this Section  8.3, the Company  shall bear the Costs
         and Expenses of such registration;  provided,  however that the Selling
         Shareholder(s)  shall  pay the fees  and  disbursements  of  their  own
         counsel and,  pro-rata  based upon the number of shares of Option Stock
         included  therein as these relate to the total number of Common  Shares
         to be  offered  or  sold,  the  Securities  Act  registration  fees and
         underwriters  discounts and compensation  attributable to the inclusion
         of such Option  Stock.  Nothing in this  Section 8.3 shall  require the
         registration  of  Option  Stock in a  Registration  Statement  relating
         solely to (a) securities to be issued by the Company in connection with
         the acquisition of the stock or the assets of another  corporation,  or
         the merger or  consolidation  of any other  corporation  by or with the
         Company  or any of its  subsidiaries,  or an  exchange  offer  with any
         corporation, (b) securities to be offered to the then existing security
         holders of the Company, or (c) securities to be offered to employees of
         the Company. In the event the distribution of securities of the Company
         covered by a Registration Statement referred to in this Section 8 is to
         be underwritten,  then the Company's obligation to include Option Stock
         in such a Registration Statement shall be subject, at the option of the
         Company, to the following further conditions:

                    (a)  The   distribution  for  the  account  of  the  Selling


                                       6



         Shareholders  shall be  underwritten by the same  underwriters  who are
         underwriting  the distribution of the securities for the account of the
         Company  and/or any other persons whose  securities are covered by such
         Registration  Statement and the Selling Shareholder(s) shall enter into
         an agreement with such underwriters containing customary provisions.

                    (b)  If  the  Selling   Shareholders  are  included  in  the
         Registration  Statement and if the underwriting  agreement entered into
         with the aforesaid  underwriters contains restrictions upon the sale of
         securities of the Company,  other than the  securities  which are to be
         included in the proposed  distribution,  for a period not  exceeding 90
         days from the effective date of the Registration  Statement,  then such
         restrictions  shall be binding  upon the  Selling  Shareholder(s)  with
         respect to any Option Stock not covered by the  Registration  Statement
         and, if requested by the underwriter,  the Selling Shareholder(s) shall
         enter into a written agreement to that effect.

                    (c) If  the  underwriters  shall state in writing  that they
         are  unwilling  to include  any or all of the  Selling  Shareholder(s)'
         Option Stock in the proposed  underwriting because such inclusion would
         materially  interfere  with the orderly  sale and  distribution  of the
         securities being offered by the Company, then the number of the Selling
         Shareholder(s)'  shares of Option Stock to be included shall be reduced
         pro  rata  on the  basis  of the  number  of  shares  of  Option  Stock
         originally requested to be included by such Selling Shareholder(s),  or
         there shall be no inclusion of the shares of the Selling Shareholder(s)
         in the Registration Statement not proposed distribution,  in accordance
         with such statement by the underwriters.

         However, if in such an event, the Holder(s) hereof shall not be able to
         include at least fifty  percent  (50%) of the Option  Stock  originally
         requested  to be included,  then the Company  shall agree to pay all of
         the Costs and Expenses of a Shelf  Registration  to be filed at a later
         date.


             9. Renewal of Exercise Rights. If, while this Option or any portion
of it remains in effect,  Holder(s)  wish to extend their rights to exercise all
or a portion of this Option  which would  otherwise  expire and be lost to them,
they may do so by paying to the  Company  Five  Cents($00.05)  per common  share
pertaining  to that  portion of the Option  which  would  otherwise  expire (the
"Renewal  Fee") and the Company  shall  extend that  portion of the Option for a
further  period of five (5) years from the date of receipt  of the  Renewal  Fee
but, in no case,  beyond 5:00 p.m.,  New York Time,  on May 15, 2006,  and shall
issue a new Option,  identical in every respect to this Option, except that such
new Option shall reflect the fact that Holder(s)  shall have an additional  five
(5) years to exercise  their rights to purchase that portion of the Option Stock
for which they have paid a Renewal Fee.  Payment of the Renewal Fee will confirm
no new rights  upon the  Holder(s)  except to extend  and renew the time  period
during which  Holder(s)  may exercise  existing  rights under this Option.  This
provision extends to this Option and all successor Option issuable hereunder.

            10.  Modification  and Waiver.  This Option and any provision hereof
may be changed,  waived,  discharged  or  terminated  only by an  instrument  in
writing signed by the party against which enforcement of the same is sought.

         11.  Notices.  Any  notice,  request  or  other  document  required  or
permitted to be given or delivered to the Holder(s)  hereof or the Company shall
be delivered or shall be sent by certified or registered mail,  postage prepaid,
to each such  Holder at its  address as shown on the books of the  Company or to
the Company at the address  indicated  therefor in the first  paragraph  of this
Option.

         12.  Fractional  Shares.  No  fractional  shares  shall be issued  upon
exercise of this Option.  The Company  shall,  in lieu of issuing any fractional
share pay the  Holder(s)  entitled  to such  fraction a sum in cash equal to the
fair market  value of any such  fractional  interest  as it shall  appear on the
public market, or if there is no public market for such shares, then as shall be
reasonably determined by the Company.

         13. Description Headings and Governing  Law.  The  descriptive headings


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of the  several  sections  and  paragraphs  of  this  Option  are  inserted  for
convenience only and do not constitute a part of this Option.  This Option shall
be construed  and  enforced in  accordance  with,  and the rights of the parties
shall be governed by, the internal laws of the State of Maryland.

             14. Validity.  If any term,  provision,  covenant or restriction of
this Option is held by a court of competent  jurisdiction to be invalid, void or
unenforceable,  the  Company  agrees  that such  term,  provision,  covenant  or
restriction  shall be  reformed  to the  extent  possible  consistent  with such
judicial holding to reflect the intent of the Company and the original Holder as
stated  herein  and  the  remainder  of the  terms,  provisions,  covenants  and
restrictions  of this Option  shall remain in full force and effect and shall in
no way be  affected,  impaired  or  invalidated.  It is  hereby  stipulated  and
declared to be the  intention  of the Company that it would have  executed  this
Option  including the remaining  terms,  provisions,  covenants and restrictions
without including any of such provision of term which may be hereafter  declared
invalid, void or unenforceable.

         IN  WITNESS  WHEREOF,   the  Company  has  caused  this   Option(Serial
Number:_________) to be executed by its officer, thereunto duly authorized as of
this 16th day of May, 1996.

                                    CHEUNG LABORATORIES, INC.

                                    By:___________________________
                                       Signature

                                    By: Augustine Y. Cheung
                                        -------------------
                                        Print Name

                                    Title: President and Chief Executive Officer
                                           -------------------------------------


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