Document:

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                                                                  EXHIBIT 10.26

[DAS LOGO]

DRUGABUSE SCIENCES, INC.
1430 O'Brien Drive, Suite E
Menlo Park, CA 94025
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TEL: (650) 462-1000     FAX: (650) 462-1003      EMAIL: ppouletty@sangstat.com

December 26, 1999

Stanley A. Kaplan, Ph.D.
2 Trinity Court
Menlo Park, CA  94025

Dear Stanley:

         This letter confirms the agreement between you and DrugAbuse
Sciences, Inc. (the "Company") regarding your separation from employment with
the Company.

         1.       Your employment with the Company will continue through and
                  until December 31, 1999. (the "Termination Date"). Effective
                  immediately and continuing through the Termination Date (the
                  "Transition Period"), you will serve as the Company's
                  President, reporting to Dr. Philippe Pouletty. Your tasks as
                  President throughout the Transition Period will be assigned at
                  Dr. Pouletty's sole discretion. You hereby agree that you
                  resign your positions as a member of the Company's Board of
                  Directors and as the Company's Chief Executive Officer
                  effective immediately.

         2.       On the Termination Date, the Company will pay you all of your
                  accrued but unused vacation pay (8 days) and all of your
                  salary earned through the Termination Date. In addition,
                  pursuant to the offer letter executed by you and the Company
                  on September 4, 1998, on the Termination Date the Company will
                  pay you a lump-sum payment of $30,834.00, less all applicable
                  withholdings, which is equal to 2 months of your current base
                  salary. You agree that the only payments and benefits that you
                  are entitled to receive from the Company in the future are
                  those specified in this letter.

         3.       Provided that you execute this letter, you and the Company
                  agree that you will serve as a part time consultant to the
                  Company for a three-month period beginning January 10, 2000
                  and continuing through April 9, 2000 (the "Consultant
                  Period"). As a consultant to the Company, you will report
                  to the Company's CEO, and will be responsible for writing
                  and seeking research grants and filing grant applications.
                  During the Consultant Period, the Company will pay you
                  $7,800 per month for 20 hours of effective work per week,
                  upon

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                  receiving corresponding work reports and invoices; you
                  will be responsible for the payment of all applicable
                  federal, state and local taxes. Throughout the Consultant
                  Period your relationship to the Company will be that of an
                  independent contractor. As an independent contractor, you
                  will not be eligible to participate in any of the Company's
                  employee benefit plans, fringe benefit programs, group
                  insurance arrangements or similar programs. You agree that
                  during the Consultant Period you will be responsible for
                  maintaining, at your own expense, a place of work, any
                  necessary equipment and supplies, and appropriate
                  communications facilities.

         4.       You understand and agree that you hold an option granted on
                  September 8, 1998, for 547,689 shares of the Company's
                  common stock at an exercise price of $0.05 (the "First
                  Option"). In addition, you hold a second option for 547,689
                  shares granted on September 8, 1998 at an exercise price of
                  $0.05 (the "Second Option"). As of the Termination Date,
                  182,489 shares of the First Option will have vested in
                  full, and 365,200 shall remain unvested. Although you are
                  not otherwise entitled to vesting of the Second Option,
                  provided that you execute this letter agreement, the Board
                  of Directors, in its sole discretion, has agreed that as of
                  the Effective Date of this letter agreement, 109,538 of the
                  shares subject to the Second Option vest in full and
                  438,051 shall remain unvested. You agree that except as
                  provided herein, all vesting of the First and Second
                  Options shall cease as of the Termination Date. You
                  acknowledge that you have no other stock rights in the
                  Company (or any parent or subsidiary) other than those
                  rights enumerated in this paragraph and all terms,
                  conditions and limitations applicable to the First and
                  Second Options as set forth in the applicable stock option
                  agreements and the Company's Stock Option Plan shall remain
                  in full force and effect. You agree to execute lock up
                  agreements requested by underwriters upon a public
                  offering, and the company will provide you with
                  corresponding stock certificates.

         5.       In consideration for entering into the above-described
                  consultant relationship with the Company, and receiving the
                  vesting of the Second Option as described above, you waive
                  and release and promise never to assert any claims or
                  causes of action, whether or not now known, against the
                  Company or its predecessors, successors, or past or present
                  subsidiaries, officers, directors, agents, employees,
                  assigns, and employee benefit plans with respect to any
                  matter, including but not limited to, any matter related to
                  your employment with the Company or the termination of that
                  employment, including, without limitation, claims of
                  wrongful discharge, emotional distress, defamation, fraud,
                  breach of contract, breach of the covenant of good faith
                  and fair dealing, any claims of discrimination or
                  harassment based on sex, age, race, national origin,
                  disability or on any other basis, under Title VII of the
                  Civil Rights Act of 1964, the California Fair Employment
                  and Housing Act, the Age Discrimination in Employment Act
                  of 1967, and all other laws and regulations relating to
                  employment.

         6.       You expressly waive and release any and all benefits under
                  Section 1542 of the CIVIL CODE OF THE STATE OF CALIFORNIA (or
                  any analogous law of any other state), which reads as follows:
                  "A general release does not extend to claims which the

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                  creditor does not know or suspect to exist in his favor at the
                  time of executing the release which, if known by him, must
                  have materially affected his settlement with the debtor."

         7.       Nothing contained in this letter shall constitute or be
                  treated as an admission by you or the Company of liability, of
                  any wrongdoing, or of any violation of law.

         8.       At all times in the future, you will remain bound by the
                  Company's Proprietary Information and Invention Agreement
                  signed by you on June 1, 1999, a copy of which is attached.

         9.       You agree that you will not disclose to others the fact or
                  terms of this letter, except that you may disclose such
                  information to your attorney or accountant in order for such
                  individuals to render services to you.

        10.       You agree that at all times in the future you will not make
                  any negative or disparaging remarks of any kind regarding the
                  Company, its employees, officers, directors, affiliates,
                  products, investors, business practices or operations. In
                  addition, you agree that you will have no communications of
                  any kind, or enter into any agreement of any kind, whether
                  oral, written or otherwise, with any current Company investor,
                  business partner, research affiliate, collaborator, advisor or
                  grant provider on matters regarding or related to the Company
                  without the prior express consent of the CEO.

        11.       You agree that except as expressly provided in this letter,
                  this letter renders null and void any and all prior agreements
                  between you and the Company. You and the Company agree that
                  this letter constitutes the entire agreement between you and
                  the Company regarding the subject matter of this agreement,
                  and that this letter may be modified only in a written
                  document signed by you and a duly authorized officer of the
                  Company.

        12.       This agreement shall be construed and interpreted in
                  accordance with the laws of the State of California.

        13.       Any controversy involving the construction or application of
                  any terms, covenants or conditions of this letter, or any
                  claims arising out of any alleged breach of this letter will
                  be governed by the rules of the American Arbitration
                  Association and submitted to and settled by final and binding
                  arbitration in Santa Clara County, California, except that any
                  alleged breach of the Company's Proprietary Information and
                  Inventions Agreement shall not be submitted to arbitration and
                  instead the Company may seek all legal and equitable remedies,
                  including, without limitation, injunctive relief.

        14.       You have up to twenty-one (21) days after receipt of this
                  letter within which to review it, and to discuss it with an
                  attorney of your own choosing regarding whether or not you
                  wish to execute it. Furthermore, you have seven (7) days after
                  you have signed this letter during which time you may revoke
                  this agreement.

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        15.       If you wish to revoke this agreement, you may do so by
                  delivering a letter of revocation to me. Because of this
                  revocation period, you understand that the agreement set forth
                  in this letter shall not become effective or enforceable until
                  the eighth day after the date you sign this letter (the
                  "Effective Date").

        Please indicate your agreement with the above terms by signing below.

                                          Sincerely,

                                          /s/ Philippe Pouletty, M.D.
                                          ------------------------------------
                                          Philippe Pouletty, M.D.

        My agreement with the terms of this letter is signified by my
signature below. Furthermore, I acknowledge that I have read and understand
this letter and that I sign this release of all claims voluntarily, with full
appreciation that at no time in the future may I pursue any of the rights I
have waived in this letter.

Dated: 12/31/99                         /s/ Stanley A. Kaplan
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                                        Stanley A. Kaplan, Ph.D.

Attachment:  Proprietary Information and Inventions Agreement<PAGE>
                                                                  EXHIBIT 10.27

[DAS LOGO]

DRUGABUSE SCIENCES, INC.
1430 O'Brien Drive, Suite E
Menlo Park, CA 94025
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     TEL:  (650) 462-1000     FAX: (650) 462-1003   E-MAIL: daskaplan@aol.com

October 18, 1999

Donald R. Wesson, MD
28 Sereno Circle
Oakland, CA  94619

          Re:  Employment Agreement

Dear Don:

On behalf of DrugAbuse Sciences, I am pleased and delighted to confirm the
terms of our agreement for you to become a DrugAbuse Sciences employee. This
offer is conditional upon your acceptance of the terms and conditions of this
offer of employment and your execution of the attached Employee Confidential
Information and Inventions Agreement.

Your position with DrugAbuse Sciences, Inc. will be Vice President, Clinical
Development, reporting to the President and CEO. As we discussed, your
position is a full-time position and your employment will commence on or
before November 15, 1999. (The date your employment commences is referred to
as your Start Date.)

Your full time base salary will be $180,000 per year, payable at the
frequency and in accordance with DrugAbuse Sciences' regularly established
payroll policies. All payments to you will be subject to legally required
withholding. It is DrugAbuse Sciences' policy to review salary and
compensation levels periodically. Accordingly, your base salary and other
compensation may be adjusted from time to time at DrugAbuse Sciences' sole
discretion; raises in compensation are not guaranteed. In addition to your
base salary, you may receive within three months following each yearend, at
the Board of Directors sole discretion, up to a 15% bonus (i.e. 15% of the
paid base salary) subject to meeting specific annual milestones (Attachment
A).

DrugAbuse Sciences also has a company Stock Option Plan (which the company
may modify from time to time) that may permit our employees to participate in
the equity ownership of the company. We expect to include you as a
participant in that plan and will recommend to the Company's Board of
Directors that you be granted a stock option for 300,000 shares; with the
exercise price equal to the fair market value on the date of grant or your
start date, whichever is later. These options will be subject to the terms of
the then applicable Stock Option Plan, and to the following vesting schedule:
(i) 37,500 shares would vest solely upon the first anniversary of continuous
employment; (ii) 3125 shares would vest monthly over the three years
subsequent to the first year anniversary; (iii) 150,000 shares would vest
solely upon the sixth anniversary of continuous employment, subject to
potential partial acceleration as follows: for each calendar year following
the Start Date, vesting for 37,500 shares may be fully accelerated at the
sole discretion of the Board of Directors, subject to fully and timely
achieving specific milestones defined annually by the Board. For year 2000,
the milestones are defined in Attachment A).

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Donald R. Wesson
October 18, 1999
Page 2

You will also be eligible to participate in the employee benefits
collectively available to our employees. We are currently evaluating several
plans including health, life, disability and 401K. Until such benefits are in
place, DrugAbuse Sciences will reimburse your Cobra medical coverage, up to a
maximum of $ 500 per month. As a regular employee of the Company, you will
accrue annually a total of twelve days vacation and be entitled to the
standard Company holidays.

You will devote your best efforts to the performance of your job for
DrugAbuse Sciences. While employed at DrugAbuse Sciences, you will not
undertake any other activity requiring your business time and attention, nor
will you support any activity that is competitive with DrugAbuse Sciences'
business or pose a conflict of interest with that business. You will follow
all DrugAbuse Sciences' policies and procedures (including our policies
protecting other employees against discrimination and sexual harassment) as
made available to you from time to time. As a condition of your employment,
you will execute DrugAbuse Sciences' Employee Confidential Information and
Inventions Agreement.

Your employment with DrugAbuse Sciences will be "at will"; in other words,
either you or DrugAbuse Sciences will have the right to terminate your
employment with DrugAbuse Sciences at any time, for any reason, with or
without notice and with or without cause, in your or our sole discretion. No
severance will apply to termination.

Don, we are very excited about your joining us. Please sign and return a copy
of this letter and the attached Employee Confidential Information and
Inventions Agreement to me, keeping a copy of each for your records. The
terms set forth in this letter supersede all prior agreements, understandings
and representations between us concerning the subject matter of this letter.
Changes to your employment agreement would apply only if in writing and
signed by the Company's CEO. We look forward to you becoming a member of our
team!

Sincerely,

/s/ Stanley A. Kaplan

Stanley A. Kaplan
President and CEO

I, Donald R. Wesson, understand and agree to the above terms. I understand
that my employment with DrugAbuse Sciences is at will, and I acknowledge that
no representations or promises other than those set forth above have been
made to me with regard to the terms and conditions of my employment.

Signed: /s/ Donald R. Wesson                  Date:    October 21, 1999
        --------------------------------            ------------------------

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Donald R. Wesson
October 18, 1999
Page 3

                                  ATTACHMENT A

I.    First year potential 15% Cash Bonus based on fully and timely achieving
      three key milestones over the first twelve months, and at the sole
      discretion of the board of directors:

      (1) For 5%: Complete Naltrel Clinical Studies and Clinical Section for
          NDA filing, such FDA and European filing being completed by the end
          of year 2000 and accepted for regulatory review.

      (2) For 5%: During 2000 design, place, implement and complete four (4)
          "Phase IV type" Naltrel Clinical Studies.

      (3) For 5%: Develop a Buprel and a COC-AB Clinical Plan, and complete
          Phase I/II COC-AB study.

II.   Vesting for a stock option for 37,500 shares may be accelerated at the
      sole discretion of the board of directors, subject to fully and timely
      achieving the following year 2000 milestones:

      (1) For 18,750 shares: Naltrel NDA FDA filing (i.e. NDA filing accepted
          for review by FDA) by the end of year 2000.

      (2) For 18,750 shares: European (mutual recognition procedure, filing
          accepted for regulatory review) Naltrel NDA filing by the end of
          year 2000.

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