EXHIBIT 10.44

February 21, 1997


McKesson Corporation
One Post Street
San Francisco, CA  94194
Attention: Alan M. Pearce,
           Assistant Treasurer


Dear Alan:

     Bank of America National Trust and Savings Association (the "Bank") is
pleased to make available to McKesson Corporation, a Delaware corporation (the
"Company") the following revolving credit facility, subject to the following
terms and conditions (terms not defined herein have the meanings assigned to
them on Attachment 1 hereto):

I.   Commitment:
     ---------- 

     The Bank agrees, on and subject to the terms and conditions set forth
     herein, to make loans to the Company (each such loan, a "Loan") from time
                                                              ----
     to time on any Business Day during the period from the Closing Date to the
     Revolving Termination Date, in an aggregate amount not to exceed at any
     time outstanding U.S. $525,000,000 (the "Commitment"). This is a revolving
                                              ----------                        
     credit facility and, within the limits of the Commitment and subject to the
     other terms and conditions hereof, the Company may borrow under this
     Agreement, prepay under Section II(F) and reborrow under this Agreement.

II.  Availability; Repayment; Etc.:
     ----------------------------- 

     A. Each Loan shall be made upon the Company's irrevocable written notice
        delivered to the Bank (which notice must be received by the Bank prior
        to 9:00 a.m. (San Francisco time) one Business Day prior to the
        requested borrowing date for Base Rate Loans or three Business Days
        prior to the requested borrowing date for Offshore Rate Loans),
        specifying (i) whether the requested Loan will be a Base Rate Loan or an
        Offshore Rate Loan (each, a "type" of Loan); (ii) the amount of the
                                     ---- 
        Loan, which shall be in a minimum amount of $10,000,000 or any integral
        multiple of $1,000,000 in excess thereof; and (iii) the requested
        borrowing date, which shall be a Business Day.

    B.  At the Company's option, each Loan shall bear interest (i) based on the
        Offshore Rate (referred to as an "Offshore Rate Loan") with an Interest
                                          ------------------                   
        Period of one, two or three months (subject to the limitations in the
        definition of Interest Period) or such period shorter than one month or
        longer than three months as the Company may request and the Bank may
        agree to in a particular instance in its sole discretion, or (ii) based
        on the Base Rate (referred to as a "Base Rate Loan").
                                            --------------   

 
    C.  Interest on any Offshore Rate Loan shall be payable on the last day of
        each Interest Period applicable to such Loan and on the Revolving
        Termination Date; provided that if any Interest Period for an Offshore
                          --------                                            
        Rate Loan exceeds three months, interest on such Loan shall also be
        payable on the date that falls three months after the beginning of such
        Interest Period. Interest on any Base Rate Loan shall be payable on the
        last Business Day of any calendar quarter and on the Revolving
        Termination Date.

    D.  At the Company's option, upon its irrevocable written notice delivered
        to the Bank (which notice must be received by the Bank prior to 9:00
        a.m. (San Francisco time) one Business Day prior to the requested
        conversion date for conversion into Base Rate Loans, or three Business
        Days prior to the requested conversion/continuation date for conversion
        into or continuation as Offshore Rate Loans), the Company may elect on
        the last day of any Interest Period applicable to an Offshore Rate Loan,
        or on any Business Day in the case of a Base Rate Loan, to convert any
        such Loan into a Base Rate Loan or Offshore Rate Loan, as applicable,
        or, on the last day of the applicable Interest Period, to continue an
        Offshore Rate Loan. Such prior written notice shall describe the
        Business Day of the proposed conversion or continuation, the portion of
        the Loans to be converted or continued (which shall be not less than
        $10,000,000 or any integral multiple of $1,000,000 in excess thereof),
        the type of Loans resulting from such conversion or continuation and, if
        applicable, the duration of the requested Interest Period (subject to
        the limitations contained in the definition of Interest Period). If the
        Company fails to give a notice of conversion or continuation or an Event
        of Default then exists, Offshore Rate Loans shall be automatically
        converted to Base Rate Loans at the end of the applicable Interest
        Period.

    E.  The Loans shall be evidenced by one or more loan accounts or records
        maintained by the Bank in the ordinary course of business. Any failure
        to record any Loan or any error in doing so shall not, however, limit or
        otherwise affect the obligation of the Company hereunder to pay any
        amount owing with respect to the Loans or otherwise owing hereunder or
        under any note given in connection herewith. In addition, the Bank may
        at any time, in its discretion, require the Company to sign one or more
        promissory notes as further evidence of such indebtedness.

    F.  Subject to Section VI(C), the Company may, at any time or from time to
        time, upon its irrevocable notice delivered to the Bank (which must be
        received by the Bank no later than 9:00 a.m. (San Francisco time) three
        Business Days prior to the proposed prepayment date, in the case of a
        prepayment of Offshore Rate Loans, or one Business Day prior to the
        proposed prepayment date, in the case of a prepayment of Base Rate
        Loans), prepay Loans in whole or in part, in minimum amounts of
        $10,000,000 or any integral multiple of $1,000,000 in excess thereof.
        Such notice of prepayment shall specify the date and amount of such
        prepayment and the type(s) of Loans to be prepaid. If such notice is
        given by the Company, the Company shall make such prepayment and the
        payment amount specified in such notice shall be due and payable on the
        date specified therein, together with accrued interest to each such date
        on the amount prepaid and any amounts required pursuant to Section
        VI(C).

    G.  The Company may, upon not less than five Business Days' prior notice to
        the Bank, terminate the Commitment, or permanently reduce the Commitment
        by a minimum amount of $10,000,000, or any integral multiple of
        $1,000,000 in excess thereof; unless, after giving effect thereto and to
                                      ------                                    
        any prepayments of Loans made on the effective date thereof, the then-
        outstanding principal amount of the Loans would

                                      -2-

 
        exceed the amount of the Commitment then in effect.  Once reduced in
        accordance with this Section II(G), the Commitment may not be increased.

    H.  The Company shall repay to the Bank on the Revolving Termination Date
        the aggregate principal amount of all Loans outstanding on such date.

III. Pricing:
     ------- 

     A. Each Loan shall bear interest at a rate per annum equal to the Offshore
        Rate or the Base Rate, as the case may be, plus the Applicable Margin.
                                                   ----                       

     B. The Company shall pay to the Bank a facility fee equal to 0.04% per
        annum times the amount of the Commitment (regardless of usage), computed
        on a quarterly basis in arrears on the last Business Day of each
        calendar quarter. Such facility fee shall accrue from the Closing Date
        to the Revolving Termination Date and shall be due and payable quarterly
        in arrears on the last Business Day of each calendar quarter, with the
        final payment to be made on the Revolving Termination Date. The facility
        fee provided in this subsection shall accrue at all times after the
        Closing Date, including at any time during which one or more conditions
        in Section IV are not met.

     C. The Company shall pay a non-refundable upfront fee for this facility in
        the amount of $65,000, payable on the Closing Date.

     D. All interest based on the Bank's reference rate (as defined in the
        definition of Base Rate) shall be calculated on the basis of a 365/366
        day year and actual days elapsed. All other interest and fees shall be
        calculated on the basis of a year of 360 days and actual days elapsed
        which results in greater interest and higher fees than if a 365 day year
        were used.

     E. Any amount not paid when due shall bear interest at a rate per annum
        equal to the sum of the Base Rate plus 1%.

IV.  Conditions for use of Facility:
     ------------------------------ 

     A. The obligation of the Bank to make its initial Loan hereunder is subject
        to the condition that the Bank has received on or before the Closing
        Date all of the following, in form and substance satisfactory to the
        Bank:

        (i)   Agreement.  This Agreement, executed by the Company;
              ---------                                           

        (ii)  Resolutions; Incumbency.  (a)  Copies of the resolutions of the
              -----------------------                                        
              board of directors of the Company authorizing the transactions
              contemplated hereby, certified as of the Closing Date by the
              Secretary or an Assistant Secretary of the Company; and (b) a
              certificate of the Secretary or an Assistant Secretary of the
              Company certifying the names and true signatures of the officers
              of the Company authorized to execute, deliver and perform, as
              applicable, this Agreement, and all other documents to be
              delivered by it hereunder;

        (iii) Organization Documents; Good Standing.  Each of the following
              -------------------------------------                        
              documents: (a) a certificate from the Secretary or Assistant
              Secretary of the Company as of the Closing Date certifying that
              the restated certificate of incorporation and the bylaws of the
              Company delivered to the Bank in connection with the 364-day
              Syndicated Credit Agreement are in full force and effect and
              unamended (except as set forth in such certificate, in which case
              such amendments shall be attached thereto) as of the Closing Date;
              and (b) a good standing and tax

                                      -3-

 
              good standing certificate for the Company from the applicable
              Secretary of State (or similar, applicable governmental authority)
              of the States of Delaware and California dated as of a recent
              date;

        (iv)  Legal Opinion.  A favorable opinion of counsel to the Company,
              -------------                                                 
              addressed to the Bank, with respect to such legal matters relating
              hereto as the Bank may reasonably request;

        (v)   Payment of Fees. Evidence of payment by the Company of all accrued
              --------------- 
              and unpaid fees, costs and expenses to the extent then due and
              payable on the Closing Date, including the fee referenced in
              Section III(C);

        (vi)  Officer's Certificate. A certificate from a responsible officer of
              ---------------------
              the Company certifying that:

              (a)  the representations and warranties in Section V are true and
              correct on and as of the Closing Date with the same effect as if
              made on and as of the Closing Date (except to the extent such
              representations and warranties expressly refer to an earlier date,
              in which case they shall be true and correct as of such earlier
              date);

              (b)  no event which, with the giving of notice or passage of time,
              or both, would constitute an Event of Default (a "Default") or
                                                                -------
              Event of Default exists or will result from the execution and
              delivery of this Agreement; and

              (c)  there has occurred since March 31, 1996, no Material Adverse
              Effect;

        (vii) Consummation of Acquisition.  Evidence satisfactory to the Bank
              ---------------------------                                    
              that the acquisition of General Medical Inc. has occurred or will
              occur on the Closing Date, including such approvals, opinions,
              certificates or materials related to such acquisition as the Bank
              may reasonably request;

       (viii) Other Documents.  Such other approvals, opinions, documents or
              ---------------                                               
              materials as the Bank may reasonably request; and

        (ix)  Closing Date.  The Closing Date shall have occurred on or before
              ------------                                                    
              March 31, 1997.

     B. Conditions to All Loans.  The obligation of the Bank to make any Loan
        -----------------------                                              
        (including the initial Loan) or to continue or convert any Loan under
        Section II(D) is subject to the satisfaction of the following conditions
        precedent on the relevant borrowing date or conversion/continuation
        date:

        (i)   Notice of Borrowing or Conversion/Continuation. The Bank shall
              ----------------------------------------------
              have received a notice of borrowing or a notice of
              conversion/continuation, as applicable;

        (ii)  Continuation of Representations and Warranties. The
              ----------------------------------------------
              representations and warranties in Section V shall be true and
              correct on and as of such borrowing date or
              conversion/continuation date with the same effect as if made on
              and as of such borrowing date or conversion/continuation date
              (except to the extent such representations and warranties
              expressly refer to an earlier date, in which case they shall be
              true and correct as of such earlier date); and

        (iii) No Existing Default.  No Default or Event of Default shall exist
              -------------------                                             
              or shall result from such Loan or continuation or conversion.

                                      -4-

 
          Each notice of borrowing and notice of conversion/continuation
          submitted by the Company hereunder shall constitute a representation
          and warranty by the Company hereunder, as of the date of each such
          notice and as of each borrowing date or conversion/continuation date,
          as applicable, that the conditions in Section IV(B) are satisfied.

     V.   Representations and Warranties. Each of the representations and
          ------------------------------
          warranties set forth in Article V (other than in Section 5.07 thereof)
          of the 364-day Syndicated Credit Agreement are incorporated herein by
          reference as if fully set forth herein, without giving effect to any
          termination of the 364-day Syndicated Credit Agreement and the Company
          hereby makes such representations and warranties to the Bank. The
          Company further represents and warrants to the Bank that the proceeds
          of the Loans are to be used solely for purposes of financing the
          acquisition of General Medical Inc. and working capital purposes
          related to such acquisition, and no part of the proceeds of any Loan
          will be used to purchase or carry any margin stock or to extend credit
          to others for the purpose of purchasing or carrying any margin stock
          or for any purpose which violates, or would be inconsistent with, the
          provisions of Regulations G, U, T and X of the Board of Governors of
          the Federal Reserve System.

     VI.  Covenants. Until the Commitment has terminated and all indebtedness of
          ---------
          Company hereunder and under any note or other document or instrument
          given in connection herewith to the Bank has been paid in full, the
          Company agrees that it shall:

          A. Comply with all of the covenants set forth in Articles VI (other
             than in Section 6.09 thereof) and VII of the 364-day Syndicated
             Credit Agreement, which are incorporated herein by reference as if
             fully set forth herein (without giving effect to any termination of
             the 364-day Syndicated Credit Agreement).

          B. Reimburse or compensate Bank, upon demand, for all costs incurred,
             losses suffered or payments made by the Bank which are applied or
             allocated by the Bank to the transactions contemplated herein (all
             as determined by the Bank in its sole and absolute discretion) by
             reason of:

             (i)   Any and all present or future reserve, deposit, capital
                   adequacy or similar requirements against (or against any
                   class of or change in or in the amount of) assets or
                   liabilities of, or extensions of credit by, the Bank; and

             (ii)  Compliance by the Bank with any direction, requirements or
                   request from any regulatory authority, whether or not having
                   the force of law.

          C. Reimburse the Bank and hold the Bank harmless from any loss or
             expense which the Bank may sustain or incur as a consequence of:
             (a) the failure of the Company to make on a timely basis any
             payment of principal of any Loan; (b) the failure of the Company to
             borrow, continue or convert any Loan after the Company has given a
             notice of borrowing; (c) the failure of the Company to make any
             prepayment in accordance with any notice delivered under Section
             II(F); (d) the prepayment or other payment (including after
             acceleration thereof) of an Offshore Rate Loan on a day that is not
             the last day of the relevant Interest Period; or (e) the automatic
             conversion under Section II(D) of any Offshore Rate Loan to a Base
             Rate Loan on a day that is not the last day of the relevant
             Interest Period.

          D. Not deduct any foreign taxes from any payments it makes to the
             Bank, if any payments to the Bank under this Agreement are made
             from outside the United States and, if any such taxes are imposed
             on any payments made by the Company (including payments under this
             Section), shall pay the taxes and will also pay to the

                                      -5-

 
             Bank, at the time interest is paid, any additional amount which the
             Bank specifies as necessary to preserve the after-tax yield the
             Bank would have received if such taxes had not been imposed. The
             Company will confirm that it has paid the taxes by giving the Bank
             official tax receipts (or notarized copies) within 30 days after
             the due date.

          E. Use the proceeds of the Loans solely for the purposes of financing
             the acquisition of General Medical Inc. and working capital
             purposes related to such acquisition and not in contravention of
             any requirement of law or of the provisions of this Agreement.

          F. The agreements of the Company in Sections VI(B),(C) and (D) above
             shall survive termination of the Commitment and payment of all
             other obligations of the Company hereunder or under any other
             document or agreement given in connection herewith.

     VII. Default.  If any of the following events ("Events of Default") shall
          -------                                                             
     occur:

          A. The Company fails to pay, (i) when and as required to be paid
             herein, any amount of principal of any Loan, or (ii) within five
             days after the same becomes due, any interest, fee or any other
             amount payable hereunder or under any other document or agreement
             given in connection herewith; or

          B. Any representation or warranty made or deemed made by the Company
             to the Bank in this Agreement or any other documents or agreements
             given in connection herewith is false or incorrect in any material
             respect on or as of the date made or deemed made;

          C. The Company shall fail to perform or observe any of its covenants
             contained in Sections 6.04(a) or Article VII of the 364-day
             Syndicated Credit Agreement, as incorporated herein by reference
             pursuant to Section VI(A) hereof;

          D. The Company shall fail in any material respect to perform or
             observe any term, covenant or agreement contained in Section VI(A)
             of this Agreement on its part to be performed or observed (other
             than those referred to in Section VII(C) above) and any such
             failure shall remain unremedied for 20 days after the earlier of
             (i) in the case of any provision in Article V or VI of the 364-day
             Syndicated Credit Agreement, as incorporated herein by reference
             pursuant to Section VI(A) hereof, the date upon which a Responsible
             Officer knew of such failure or (ii) the date upon which written
             notice thereof is given to the Company by the Bank;

          E. The Company fails to comply in any material respect with any other
             condition, covenant or obligation contained herein or in any other
             documents or agreements given in connection herewith (other than
             those referred to in Section VII(C) and (D) above), and any such
             failure shall remain unremedied for 20 days after written notice
             thereof shall have been given to the Company by the Bank; or

          F. An Event of Default occurs under the 364-day Syndicated Credit
             Agreement; provided that if the 364-day Syndicated Credit Agreement
             is terminated, the Events of Default set forth in Section 8.01(e)
             through (h) of the 364-day Syndicated Credit Agreement shall be
             incorporated herein by reference as though fully set forth herein;

          THEN, the Bank may (i) declare any Commitment by the Bank to extend
          additional credit hereunder to be terminated, whereupon any such
          Commitment shall be terminated, and (ii) declare all sums outstanding
          hereunder or under any instrument executed in connection herewith to
          be immediately due and payable together with all interest thereon,

                                      -6-

 
          all without notice of default, presentment or demand for payment,
          protest or notice of nonpayment or dishonor, or other notices or
          demands of any kind or character, all of which are hereby expressly
          waived; provided, however, that upon the occurrence of any event
                  --------  -------
          specified in subsection (f) or (g) of Section 8.01 (in the case of
          clause (i) of subsection (g) upon the expiration of the 60-day period
          mentioned therein) of the 364-day Syndicated Credit Agreement, any
          Commitment by the Bank to extend additional credit hereunder shall
          automatically terminate, and all sums outstanding hereunder or under
          any instrument executed in connection herewith shall become
          immediately due and payable together with all interest thereon, all
          without notice of default, presentment or demand for payment, protest
          or notice of nonpayment or dishonor, or other notices or demands of
          any kind or character, all of which are hereby expressly waived.

VIII. Miscellaneous.
      ------------- 

     A. The Company shall pay the Bank, on demand, all out-of-pocket expenses
        and Attorney Costs incurred by Bank in connection with the development,
        preparation, delivery, administration and execution of, and any
        amendment, supplement, waiver or modification to (in each case, whether
        or not consummated), and the enforcement of this Agreement and any
        instruments or agreements executed in connection with this Agreement.

     B. This Agreement shall be governed by and construed in accordance with the
        laws of the State of California, to the jurisdiction of whose courts,
        both state and federal all signatories hereto submit.

     C. Except as may be specifically provided herein, this Agreement supersedes
        all prior agreements and oral negotiations with respect to the subject
        matter of this Agreement. This Agreement is not assignable by the
        Company without the prior written consent of the Bank, and is not
        assignable by the Bank except as provided in Section VIII(E).

     D. Whether or not the transactions contemplated hereby are consummated, the
        Company shall indemnify, defend and hold the Bank and each of its
        officers, directors, employees, counsel, agents and attorneys-in-fact
        (each, an "Indemnified Person") harmless from and against any and all
                   ------------------                                        
        liabilities, obligations, losses, damages, penalties, actions,
        judgments, suits, costs, charges, expenses and disbursements (including
        Attorney Costs) of any kind or nature whatsoever which may at any time
        (including at any time following repayment of the Loans) be imposed on,
        incurred by or asserted against any such person in any way relating to
        or arising out of this Agreement or any document contemplated by or
        referred to herein, or the transactions contemplated hereby, or the
        acquisition of General Medical Inc. and any transaction related thereto
        or any action taken or omitted by any such person under or in connection
        with any of the foregoing, including with respect to any investigation,
        litigation or proceeding (including any insolvency proceeding or
        appellate proceeding) related to or arising out of this Agreement or the
        Loans or the use of the proceeds thereof, whether or not any Indemnified
        Person is a party thereto (all the foregoing, collectively, the
        "Indemnified Liabilities"); provided, that the Company shall have no
         -----------------------    --------  
        obligation hereunder to any Indemnified Person with respect to
        Indemnified Liabilities resulting solely from the gross negligence or
        willful misconduct of such Indemnified Person. The agreements in this
        Section VIII(D) shall survive termination of the Commitment and payment
        of all other obligations of the Company hereunder or under any other
        document or agreement given in connection herewith.

                                      -7-

 
     E. (i)   The Bank may at any time and from time to time, with the prior
              written consent of the Company, at all times other than during the
              existence of an Event of Default, which consent shall not be
              unreasonably withheld (provided, that no consent of the Company
                                     --------
              shall be required in connection with any assignment and delegation
              by the Bank to an affiliate of the Bank), assign and delegate to
              one or more commercial banks (each an "Assignee") all, or any part
                                                     --------
              of all, of the Loans, the Commitment and the other rights and
              obligations of the Bank hereunder, in a minimum amount of
              $10,000,000; provided, however, that the Company may continue to
                           --------  -------  
              deal solely and directly with the Bank in connection with the
              interest so assigned to an Assignee until written notice of such
              assignment, together with payment instructions, addresses and
              related information with respect to the Assignee, shall have been
              given to the Company by the Bank and the Assignee.

        (ii)  The Bank may at any time and from time to time, with the prior
              written consent of the Company, at all times other than during the
              existence of an Event of Default, which consent shall not be
              unreasonably withheld (provided, that no consent of the Company
                                     --------                                
              shall be required in connection with any sale of a participating
              interest by the Bank to an affiliate of the Bank) sell to one or
              more financial institutions (a "Participant") participating
                                              -----------                
              interests in any Loans, the Commitment and the other interests of
              the Bank hereunder and under the other loan documents.

        (iii) Notwithstanding any other provision in this Agreement, the Bank
              may at any time create a security interest in, or pledge, all or
              any portion of its rights under and interest in this Agreement in
              favor of any Federal Reserve Bank in accordance with Regulation A
              of the Board of Governors of the Federal Reserve System or 31 U.S.
              Treasury Regulation CFR (S)203.14, and such Federal Reserve Bank
              may enforce such pledge or security interest in any manner
              permitted under applicable law.

     F. All payments to Bank shall be made by wire transfer to its Global
        Payments Operations, 1850 Gateway Ave., Concord, California 94520 in
        same day funds; for credit to Incoming Money Transfer Account #12331-
        83980, ABA #121-000-358; Ref: McKesson Corporation.

     G. No delay or omission by Bank to exercise any right under this Agreement
        or under any document related hereto shall impair such right, nor shall
        it be construed as a waiver thereof. No waiver of any breach or default
        shall be deemed a waiver of any subsequent breach or default. Any
        waiver, consent or approval under this Agreement must be in writing to
        be effective.

     H. Section headings in this Agreement are for reference only and shall not
        affect the interpretation of any provision of this Agreement. Any
        defined terms, schedules or exhibits referenced in provisions of the 
        364-day Syndicated Credit Agreement which are incorporated herein by
        reference shall be incorporated herein as well (without giving effect to
        any termination of such 364-day Syndicated Credit Agreement). Provisions
        of the 364-day Syndicated Credit Agreement which are incorporated herein
        by reference shall be deemed to include the following interpretive
        changes: (i) references to "this Agreement" or "the Agreement" shall be
        deemed to be references to this Agreement and references to "Notes" or
        "Note" shall be deemed to be references to any note given in connection
        herewith; (ii) references to the "Agent", the "Banks", the "Majority
        Banks" or to any "Bank" or any combination thereof shall be deemed to be
        references to the Bank; (iii) references to the "Closing

                                      -8-

 
        Date" shall be deemed to be references to the Closing Date hereunder;
        (iv) references to a "Material Adverse Effect" shall be deemed to be
        references to a Material Adverse Effect as defined herein; and (v)
        references to an "Event of Default" or "Default" shall be deemed to be
        references to such events under the 364-day Syndicated Credit Agreement
        or hereunder.

     I. THE COMPANY AND THE BANK EACH WAIVE THEIR RESPECTIVE RIGHTS TO A TRIAL
        BY JURY OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF OR
        RELATED TO THIS AGREEMENT, THE OTHER DOCUMENTS GIVEN IN CONNECTION
        HEREWITH, OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY, IN ANY
        ACTION, PROCEEDING OR OTHER LITIGATION OF ANY TYPE BROUGHT BY ANY OF THE
        PARTIES AGAINST ANY OTHER PARTY, WHETHER WITH RESPECT TO CONTRACT
        CLAIMS, TORT CLAIMS, OR OTHERWISE. THE COMPANY AND THE BANK EACH AGREE
        THAT ANY SUCH CLAIM OR CAUSE OF ACTION SHALL BE TRIED BY A COURT TRIAL
        WITHOUT A JURY.

     J. This letter may be signed in counterparts, and by each party on separate
        counterparts, each of which, when so executed, shall be deemed an
        original, and all of said counterparts taken together shall be deemed to
        constitute but one and the same instrument.

                                      -9-

 
       Please indicate your acceptance of the foregoing terms and conditions by
signing and returning a copy of this letter to my attention no later than March
31, 1997.


                               Sincerely yours,

                               BANK OF AMERICA NATIONAL TRUST
                               AND SAVINGS ASSOCIATION

                               By:_____________________________

                               Name:___________________________


                               Title:__________________________

Agreed and Accepted:

MCKESSON CORPORATION


By:___________________________
   
Name:_________________________

Title:________________________


By:___________________________

Name:_________________________

Title:________________________


Date:   ________________, 1997

                                      -10-

 
                                  ATTACHMENT 1
                                  ------------



Agreement:    means this letter loan agreement, as it may be modified, amended,
- ---------     or supplemented from time to time.
              
Applicable
- ----------
Margin:       means (i) with respect to Offshore Rate Loans, 0.11% per annum,
- ------        and (ii) with respect to Base Rate Loans, 0.00% per annum.
              
Attorney
- --------
Costs:        means and includes all fees and disbursements of any law firm or
- -----         other external counsel, the allocated cost of internal legal
              services and all disbursements of internal counsel.  
              
Base
- ----
Rate:         means, for any day, the higher of: (a) 0.50% per annum above the
- ----          latest Federal Funds Rate, which means, for any day, the rate set
              forth in the weekly statistical release designated as H.15(519),
              or any successor publication, published by the Federal Reserve
              Bank of New York (including any such successor, "H.15(519)") on
              the preceding Business Day opposite the caption "Federal Funds
              (Effective)"; or, if for any relevant day such rate is not so
              published on any such preceding Business Day, the rate for such
              day will be the arithmetic mean as determined by the Bank of the
              rates for the last transaction in overnight Federal funds arranged
              prior to 9:00 a.m. (New York City time) on that day by each of
              three leading brokers of Federal funds transactions in New York
              City selected by the Bank; and (b) the rate of interest in effect
              for such day as publicly announced from time to time by the Bank
              in San Francisco, California, as its "reference rate." (The
              "reference rate" is a rate set by the Bank based upon various
              factors including the Bank's costs and desired return, general
              economic conditions and other factors, and is used as a reference
              point for pricing some loans, which may be priced at, above, or
              below such announced rate.) Any change in the reference rate
              announced by the Bank shall take effect at the opening of business
              on the day specified in the public announcement of such change.

Business Day: means any day other than a Saturday, Sunday or other day on which
- ------------  commercial banks in San Francisco are authorized or required by
              law to close and, if the applicable such Business Day relates to
              an Offshore Rate Loan, also means such a day on which dealings are
              carried on in the applicable offshore dollar interbank market.
                                                                  
Closing
- -------
Date:         means the date on which all conditions precedent set forth in
- ----          Section IV(A) are satisfied or waived by the Bank.

Interest
- --------
Period:       means, (a) as to any Offshore Rate Loan, the period commencing on
- ------        the borrowing date of such Loan or on the date on which the Loan
              is converted into or continued as an Offshore Rate Loan, and
              ending on the date one, two



 
              or three months thereafter as selected by the Company in its
              notice of borrowing or notice of conversion/continuation and (b)
              as to any Offshore Rate Loan, the period commencing on the
              borrowing date of such Loan or on the date on which the Loan is
              converted into or continued as such type of Loan, such period
              shorter than one month or longer than three months as the Company
              may request and the Bank may agree to in a particular instance in
              its sole discretion; provided, that:
                                   --------------

              (i)   if any Interest Period would otherwise end on a day that is
                    not a Business Day, that Interest Period shall be extended
                    to the following Business Day unless, in the case of an
                    Offshore Rate Loan, the result of such extension would be to
                    carry such Interest Period into another calendar month, in
                    which event such Interest Period shall end on the preceding
                    Business Day;

              (ii)  any Interest Period pertaining to an Offshore Rate Loan that
                    begins on the last Business Day of a calendar month (or on a
                    day for which there is no numerically corresponding day in
                    the calendar month at the end of such Interest Period) shall
                    end on the last Business Day of the calendar month at the
                    end of such Interest Period; and

              (iii) no Interest Period for any loan shall extend beyond the
                    Revolving Termination Date as determined by subsection (a)
                    of the definition of that term.

Material
- --------
Adverse
- -------
Effect:       means (a) a material adverse change in, or a material adverse
- ------        effect upon, the operations, business, properties, condition
              (financial or otherwise) or prospects of the Company and its
              Subsidiaries taken as a whole or any Material Subsidiary; (b) a
              material impairment of the ability of the Company to perform under
              this Agreement or any document related hereto and to avoid any
              Event of Default; or (c) a material adverse effect upon the
              legality, validity, binding effect or enforceability against the
              Company of this Agreement or any document or agreement given in
              connection herewith.

Offshore
- --------
Rate:         means, for any Interest Period, with respect to an Offshore Rate
- ----          Loan, the rate of interest per annum (rounded upward to the next
              1/16th of 1%) determined by the Bank as follows:
              
              Offshore Rate=                 LIBOR
                               ------------------------------------
                               1.00 - Eurodollar Reserve Percentage

              Where,

                   "Eurodollar Reserve Percentage" means for any day for any
                    -----------------------------                           
              Interest Period the maximum reserve percentage (expressed as a
              decimal, rounded upward to the next 1/100th of 1%) in effect on
              such day (whether or not applicable to the Bank) under regulations
              issued from time to time by the Board of Governors of the Federal
              Reserve System for determining the maximum reserve requirement
              (including any emergency, supplemental or other marginal

                                      -2- 

 
              reserve requirement) with respect to Eurocurrency funding
              (currently referred to as "Eurocurrency liabilities"); and

                   "LIBOR" means the rate of interest per annum determined by
                    -----
               the Bank as the rate of interest at which dollar deposits in the
               approximate amount of the Loan to be made or continued as, or
               converted into, an Offshore Rate Loan and having a maturity
               comparable to such Interest Period would be offered by the Bank
               to major banks in the London interbank market at their request at
               approximately 11:00 a.m. (London time) two Business Days prior to
               the commencement of such Interest Period.

                   The Offshore Rate shall be adjusted automatically as to all
               Offshore Rate Loans then outstanding as of the effective date of
               any change in the Eurodollar Reserve Percentage.

Revolving
- ---------
Termination
- -----------
Date:          means the earlier to occur of (a) the date which is 180 days
- ----           after Closing Date, and (b) the date on which the Commitment
               terminates in accordance with the provisions of this Agreement.

               
364-day
- -------
Syndicated
- ----------
Credit
- ------
Agreement:    means the Credit Agreement dated as of November 4, 1996 among the
- ---------     Company, the financial institutions party thereto, The Chase
              Manhattan Bank, as Co-Agent, and Bank of America National Trust
              and Savings Association, as Agent, as the same may be amended,
              modified, supplemented, extended, or restated, or as the terms
              thereof may be modified or waived by any amendment, modification,
              supplement, extension, restatement or waiver.

                                      -3-