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       PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED BASED ON A REQUEST FOR
                              CONFIDENTIAL TREATMENT

                                                                 Exhibit 10.22

                                LICENSE AGREEMENT

     This License Agreement ("AGREEMENT") is made as of this 16 day of
August, 2000 (the "EFFECTIVE DATE") by and between ABBOTT LABORATORIES, an
Illinois corporation, with its principal office at 100 Abbott Park Road,
Abbott Park, IL 60064 ("ABBOTT") and DRUG ABUSE SCIENCES, INC., a California
corporation, with its principal office at 330 Distel Circle, Suite 150, Los
Altos, CA 94022 ("DAS").

                                   WITNESSETH

     WHEREAS, Abbott is the holder of certain patent applications and patents
("PATENTS," as more fully defined below) relating to Compound (as defined
below);

     WHEREAS, Abbott also possesses proprietary Know-How (as defined below)
relating to Compound and/or Product (as defined below);

     WHEREAS, DAS wishes to obtain, and Abbott wishes to grant to DAS and its
Affiliates (as defined below), an exclusive license in the Territory (as defined
below) under the Patents and Know-How for the development and commercialization
of Product for Pharmaceutical Uses (as defined below); and

     WHEREAS, DAS and Abbott acknowledge that there is substantial additional
formulation and clinical work to be done in order to successfully develop and
commercialize Product.

     NOW THEREFORE, in consideration of the mutual obligations and promises as
set forth herein, the parties do hereby agree as follows:

1.   DEFINITIONS. As used in this Agreement, the following terms shall have the
following respective meanings:

     1.1  "ABBOTT'S TECHNOLOGY" means the Patents and Know-How, including all
          Improvements developed by Abbott.

     1.2  "ABT-431" means the following pure form of the compound more
          specifically described as:[******]

     1.3  [******][******][******]"AFFILIATE" means any corporation, company,
          partnership, joint venture and/or firm which controls, is controlled
          by, or is under common control of either party hereto. For purposes of
          this definition, control shall mean direct or indirect ownership of
          more than fifty percent (50%) of the stock or participating shares
          entitled to vote for the election of directors (but only as long as
          such ownership exists).

     1.4  "COMPOUND" means any and all tetracyclic compounds with the following
          formula:

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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        [******]

     1.5  "CONFIDENTIAL INFORMATION" means any and all information or data
          relating to the Compound and/or Product which a party discloses to the
          other party, its employees or representatives, or is conceived or
          reduced to practice during the Term by either party or by a third
          party conducting feasibility and evaluation studies for DAS, whether
          in writing, orally or by observation, including, without limitation,
          all scientific, clinical, technical, commercial, financial and
          business information and Know-How, and other information or data
          considered confidential in nature. The Confidential Information of DAS
          shall also include: (i) the fact that DAS intends to develop, use or
          market any particular product, process or system; and (ii) all
          information concerning the business, products, marketing efforts,
          technology or finances of DAS. Subject to SECTION 7.1 hereof, Abbott
          shall hold in confidence and shall not directly or indirectly disclose
          or provide to any third party information pertaining to the Compound,
          the Process Technology or Abbott Technology without DAS's prior
          written consent. Confidential Information shall not include
          information or any portion thereof which:

          (a)  is known to the receiving party at the time of disclosure and
               documented by written records made prior to the date of this
               Agreement;

          (b)  is subsequently disclosed to the receiving party without any
               obligations of confidence by an unaffiliated third person who has
               not obtained it directly or indirectly from the other party and
               who has the right to make such disclosure;

          (c)  becomes patented, published or otherwise part of the public
               domain;

          (d)  is independently developed by or for the receiving party by
               person(s) having no knowledge of or access to such information
               and without breach of any confidentiality obligation as evidenced
               by its written records; or

          (e)  is required to be disclosed by legal, regulatory, statutory or
               governmental process or authorities, provided in each case the
               party disclosing information promptly informs the other and uses
               its best efforts to limit the disclosure and to maintain
               confidentiality to the maximum extent possible and permits the
               other party to attempt by appropriate legal means to limit such
               disclosure.

          The contents of and the Exhibits to this Agreement shall constitute
Confidential Information.

     1.6  [******]

     1.7  "EFFECTIVE DATE" shall have the meaning ascribed to such term in the
          opening paragraph of this Agreement.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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     1.8  "FIRST COMMERCIAL SALE" means the first sale of Product in the
          Territory, after Regulatory Approval, by DAS or its Affiliates (or
          their sublicensee(s)) to any unaffiliated third party as evidenced by
          the selling party's invoice or other relevant document to such third
          party. A sale to an unaffiliated third party shall not include
          quantities delivered solely for research purposes, for clinical trials
          or quantities distributed as samples or promotions.

     1.9  "IMPROVEMENTS" means all additions, developments, modifications,
          enhancements and adaptations (i) which directly relate to or are used
          in connection with the Process Technology or any Pharmaceutical Uses,
          or any formulations thereof or additions, developments, modifications,
          enhancements, improvements and adaptations thereto, and (ii) which are
          conceived or reduced to practice during the Term. Ownership of
          Improvements shall be as set forth in ARTICLE 13 hereof.

     1.10 "IND" means an investigational new drug application filed with the
          applicable Regulatory Authority in a country of the Territory, in
          order to commence human clinical testing of a drug. An IND, together
          with all supplemental filings referencing the initial IND filing,
          shall be deemed one and the same IND for all purposes of this
          Agreement.

     1.11 "KNOW-HOW" means any proprietary technology, information, methods of
          use, processes, techniques or ideas or inventions (other than the
          Patents) owned, possessed or used by Abbott as of the Effective Date
          which is directly related to or used in connection with the Process
          Technology or any Pharmaceutical Uses, including all trade secrets and
          any other technical information relating to development, use or sale
          of the Compound and/or Product, provided that Abbott has the right to
          license and/or sublicense to DAS. To the best of Abbott's knowledge
          and belief, Abbott has the right to license and/or sublicense
          substantially all of the Know-How.

     1.12 "NDA" means an application (whether original, supplementary or
          abbreviated) to the applicable Regulatory Authority in a country of
          the Territory, for approval by such Regulatory Authority, necessary
          for the commercial sale of Product in such country. An NDA, together
          with all supplemental filings referencing the initial NDA filing,
          shall be deemed one and the same NDA for all purposes of this
          Agreement.

     1.13 "NET SALES" means gross sales of the Product by DAS, by any Affiliates
          of DAS, or any contract sales force of DAS or its Affiliates to
          unrelated third parties, in arm's length transactions, including, but
          not limited to, pharmaceutical wholesalers, pharmacies, hospitals or
          dispensing physicians, less any of the following charges or expenses
          that are incurred in connection with gross sales of the Product during
          the Term:

[******] Confidential Treatment Requested. The confidential portions have
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          (a)  discounts, including cash discounts, customary trade allowances
               or rebates actually taken, governmental rebates, chargebacks,
               commissions, and group purchasing management fees for formulary
               access;

          (b)  credits or allowances given or made for rejection, recall or
               return of previously sold Product actually taken;

          (c)  any tax or government charge, duty or assessment (including any
               tax such as a value added or similar tax or government charge)
               levied on the sale, transportation or delivery of Product when
               included on the invoice or other written document between the
               parties as payable by the purchaser and collectable by DAS, its
               Affiliate or sub-licensee; and

          (d)  freight, postage, transportation, insurance and duties on
               shipment of Product when included on the invoice or other written
               document between the parties as payable by the purchaser and
               collectable by DAS, its Affiliate or sublicensee.

     1.14 "PATENTS" means the patent applications and patents listed in Exhibit
          A hereto and any and all other patent applications and patents and
          amendments thereto, including foreign equivalents, and any and all
          substitutions, extensions, additions, reissues, re-examinations,
          renewals, divisions, continuations, continuations-in-part or
          supplementary protection certificates owned by or licensed to (with
          the right to sublicense) Abbott during the Term relating to the
          Product or any Improvements.

     1.15 "PHARMACEUTICAL USES" means any therapeutic use of the Compound and/or
          Product for the management of a disease or condition of the human
          body, excluding (a) any non-therapeutic use or non-human use (which
          non-therapeutic or non-human use shall include, but not be limited to,
          imaging, diagnostics, veterinary medicine, etc.), and (b) [******]

     1.16 "PROCESS TECHNOLOGY" means any technology within the scope of the
          claims of U.S. Patent No. 5,659,037 and/or any foreign equivalents
          listed on EXHIBIT D that are necessary or used for making, using or
          selling Compound and/or Product, and any and all other patent
          applications and patents and amendments thereto, and any and all
          substitutions, extensions, additions, reissues, re-examinations,
          renewals, divisions, continuations, continuations-in-part or
          supplementary protection certificates owned by or licensed to (with
          the right to sublicense) Abbott during the Term relating to the
          Process Technology and applicable to any Compound that are necessary
          or used for making, using or selling Compound and/or Product.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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     1.17 "PRODRUG" means different pharmaceutical compounds which, following
          administration, are converted into structurally similar active
          metabolites.

     1.18 "PRODUCT" means any formulation containing the Compound or any
          Improvement as an active ingredient for Pharmaceutical Uses.

     1.19 "REGULATORY APPROVAL" means all governmental approvals and
          authorizations necessary for the manufacture and commercial sale of
          the Product in a country of the Territory, including, but not limited
          to, marketing authorization, pricing approval and pricing
          reimbursement, as applicable.

     1.20 "REGULATORY AUTHORITY" means the United States Food and Drug
          Administration or any successor entity and its equivalent in other
          countries of the Territory, including, but not limited to, EMEA.

     1.21 "ROYALTY PERIOD" shall have the meaning ascribed to such term in
          SECTION 5.7(a) of this Agreement.

     1.22 "SUBSTANCE ABUSE INDICATION" shall mean any treatment of addiction
          (including, but not limited to, addiction to cocaine, heroin,
          methamphetamine, and alcohol).

     1.23 "TERM" means the period commencing on the Effective Date and
          terminating as set forth in ARTICLE 8 below.

     1.24 "TERRITORY" means the entire world.

     1.25 "TRADEMARK" means any trademark registered, owned and chosen for
          Product by DAS in any country of the Territory.

     1.26 "WORK PLAN" means each "Feasibility and Development Work Plan"
          specific to each Product indication attached hereto as EXHIBIT B, B-2,
          B-3, etc.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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2.   LICENSE GRANT. Abbott hereby grants to DAS and its Affiliates an exclusive
right and license in the Territory, under Abbott's Technology and the Process
Technology, for all Pharmaceutical Uses, with the right to grant sublicenses
pursuant to SECTION 4.7 hereof, to: (i) research, develop, modify, improve, make
or have made, Compound and Product; (ii) apply for and obtain Regulatory
Approvals, all as may be required to manufacture and commercialize Product; and
(iii) make, have made, register, use, import/export, market, offer to sell and
sell, Product and Compound, including co-promotion and co-marketing. During the
development phase of the Product, DAS shall have the right to use the Compound
for therapeutic drug monitoring for research and development purposes only. If a
Regulatory Authority requires therapeutic drug monitoring as a part of Product
labeling in connection with NDA approval, then DAS will offer Abbott the first
opportunity to develop and market such a therapeutic drug monitoring assay.
Should Abbott be unable or unwilling to develop and market such an assay within
a commercially reasonable time period, then DAS will have a non-exclusive
royalty bearing license to develop (or have developed) and commercialize such
assay with a royalty rate payable by DAS to Abbott of [******] of such assay.

3.   INFORMATION; EXCLUSIVITY.

     3.1  CONVEYANCE OF INFORMATION/INVENTORY:

          (a)  Within forty-five (45) days following the Effective Date, Abbott
               shall convey to DAS most of the information under Abbott's and
               its Affiliates' control involving the Compound, the Process
               Technology and Pharmaceutical Uses of the Compound, including but
               not limited to all information relating to Patents and Know-How,
               worldwide regulatory documentation, draft and final clinical
               reports, toxicity study reports, manufacturing protocol and batch
               records, claims related to potential violations of any third
               party rights, and all collaborative research agreements in the
               possession of Abbott, its Affiliates and agents, but excluding
               raw data sources which are not customarily required for
               regulatory submission (e.g., laboratory notebooks and other
               laboratory databases) and all information related to
               non-Pharmaceutical Uses of the Compound. Abbott shall use
               reasonable efforts in good faith to provide any remaining
               information in the following forty-five (45) days. Abbott will
               promptly provide DAS any other such information of which it
               becomes aware during the term of this Agreement. With regard to
               information from raw data sources, in the event that such
               information is requested from DAS by a Regulatory Authority,
               Abbott shall use reasonable efforts to provide DAS with such
               information. If such information is requested for other purposes,
               Abbott shall use reasonable efforts to provide DAS with such
               information pursuant to SECTION 3.3 of this Agreement or, if
               SECTION 3.3 is no longer applicable or if DAS so requests,
               [******]. For purposes of this SECTION 3.1, information shall not
               be deemed under Abbott's and its Affiliates' control if such
               information is protected by confidentiality agreements with third
               parties. With respect to such protected information, Abbott shall
               use reasonable efforts to obtain the consent of such third
               parties to release the protected information to DAS.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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          (b)  Abbott shall convey to DAS all available inventory of the
               Compound as requested by DAS, except for such quantities
               required by Abbott in connection with internal research
               purposes and non-Pharmaceutical Uses and/or internal research
               uses of the Compound. Any inventory of Compound conveyed to
               DAS under this SECTION 3.1(b) shall be conveyed "AS IS" and
               "WITH ALL FAULTS," WITHOUT WARRANTY OF ANY KIND WHATSOEVER,
               EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY
               AND FITNESS FOR PARTICULAR PURPOSE. DAS shall pay Abbott
               [******] per kilogram of compound conveyed under this SECTION
               3.1(b). DAS shall be responsible for all testing, quality
               control and certification of such Compound.

     3.2  ABBOTT EXCLUSIVITY.

          (a)  During the Term, and except as described in SECTION 4.3(a),
               neither Abbott nor its Affiliates, shall directly or through
               intermediaries, undertake any development or commercialization
               activities related to Pharmaceutical Uses, except that Abbott
               shall be entitled to utilize the Compound for its internal
               research purposes (including pharmaceutical research), provided
               in no event shall such utilization permit Abbott to develop
               and/or commercialize Pharmaceutical Uses. For the avoidance of
               doubt, Abbott shall have the express right to undertake
               development and commercialization activities relating to the
               Compound for non-Pharmaceutical Uses.

          (b)  For a period of five (5) years after the Effective Date, neither
               Abbott nor its Affiliates shall undertake any development or
               commercialization activities with respect to any [******] for any
               Substance Abuse Indication. Notwithstanding the foregoing, Abbott
               shall have the express right to undertake development and
               commercialization activities relating to [******] for
               non-therapeutic and/or non-human uses even if related to
               Substance Abuse Indication (which non-therapeutic uses and/or
               non-human uses shall include, but not be limited to, imaging,
               diagnostics, veterinary medicine, etc.). For the avoidance of
               doubt, Abbott shall also have the express right to undertake
               development and commercialization activities relating to [******]
               (excluding any Compound for Pharmaceutical Uses) for any use or
               indication other than any Substance Abuse Indication, as set
               forth above.

          (c)  Notwithstanding SECTIONS 3.2(a) and (b) above, Abbott shall have
               the right to use the Process Technology solely in connection with
               compounds or products that are not, and do not contain, Compound,
               and in its development and commercialization activities related
               to the Compound as permitted in this Agreement.

     3.3  ASSISTANCE. During the period commencing on the Effective Date and
          ending on the first submission to a Regulatory Authority for
          Regulatory Approval of the

[******] Confidential Treatment Requested. The confidential portions have
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          third Product indication, Abbott will use commercially reasonable
          efforts to provide DAS information (in the possession of Abbott) and
          assistance as reasonably required by DAS for regulatory purposes in
          connection with this Agreement, provided, that in no event shall
          Abbott be obligated to incur expenses as a result of providing such
          assistance nor shall Abbott employees be required to spend a
          substantial amount of time (collectively, not more than twenty (20)
          hours) providing such assistance. In the event that additional time is
          required by DAS, the parties shall negotiate in good faith a mutually
          acceptable hourly rate to be charged DAS for such Abbott employee
          time.

     3.4  DAS EXCLUSIVITY. During the Term, neither DAS nor its Affiliates nor
          their sublicensees, shall directly or through intermediaries, utilize
          the Process Technology for any purpose other than developing, making,
          using or selling Compound and/or Product under this Agreement.

4.   FEASIBILITY/EVALUATION/DEVELOPMENT/MANUFACTURING/MARKETING/OTHER.

     4.1  FEASIBILITY/EVALUATION STUDIES:

          (a)  DAS shall use commercially reasonable efforts to evaluate the
               Compound for at least three (3) indications of Pharmaceutical
               Uses. As of the Effective Date, the parties acknowledge that only
               cocaine abuse and Parkinson's Disease are recognized indications
               for the Compound. For purposes of DAS's obligations under this
               Agreement or any Work Plan, the term "commercially reasonable
               efforts" shall mean those efforts that would be commercially
               reasonable for a company substantially similar to DAS as set
               forth generally in the initial Work Plan (EXHIBIT B). DAS shall
               have sole responsibility for conducting and/or supervising the
               feasibility and evaluation studies on the Compound as set forth
               in the Work Plan (EXHIBIT B), which Work Plan shall include a
               schedule of the clinical development activities to be conducted
               by DAS for the first indication under SECTION 4.3 below.
               Beginning with the Effective Date and until the First Commercial
               Sale, DAS shall use commercially reasonable efforts to conduct
               and/or supervise the studies called for by the Work Plan. All
               such studies shall be paid for by DAS. DAS shall provide Abbott
               with summaries of such studies, including summaries of reports
               and data generated under such studies, at the quarterly review
               meetings held pursuant to SECTION 4.2 below (or otherwise), and
               all such information shall be treated as DAS's Confidential
               Information. Periodically, as the progress of the studies may
               dictate, the Work Plan may be amended at DAS's reasonable
               discretion, and such amendments shall be reflected in an amended
               EXHIBIT B to be prepared, distributed, and attached hereto by
               DAS. Recognizing that the Work Plan calls for certain work to be
               done by one or more third parties and recognizing such work
               (e.g., formulations) may involve the patented subject matter of
               such third party, DAS will use commercially reasonable efforts to
               (i) provide in its license with the third party that the patented
               subject matter of such third party

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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               may be sublicensed to Abbott in the event that the Compound and
               Product are returned to Abbott under SECTIONS 4.3(c) and 4.8; and
               (ii) negotiate a royalty-free license/sublicense with such third
               party. In the event that DAS is unable to negotiate a
               royalty-free license/sublicense, Abbott agrees to assume the
               royalty obligations thereunder if it elects to practice under
               such license/sublicense following the return of the Compound and
               Product under SECTIONS 4.3(c) and 4.8. DAS agrees to promptly
               provide Abbott with written notice of the terms of any licenses
               entered into with third parties which pertain to the Compound
               and/or Product.

          (b)  Upon commencement of work to develop the second and subsequent
               indications of the Product, DAS shall provide Abbott with a Work
               Plan for the feasibility and evaluation studies and for the
               clinical development activities on the Compound that it proposes
               to undertake with respect to the second and subsequent Product
               indications, which Work Plan shall contain substantially similar
               content and time frames as provided in the initial Work Plan
               attached hereto. Such Work Plan shall be in the same general form
               as that provided for in SECTION 4.1 above, shall be attached to
               this Agreement as EXHIBIT B-2, B-3, etc., and shall be subject to
               the same rights of amendment, license and review as provided
               herein, including Abbott's rights to initiate an ADR under
               SECTION 4.3(c).

     4.2  REVIEW: Beginning one month following the Effective Date and until the
          First Commercial Sale, three (3) representatives of Abbott and three
          (3) representatives of DAS shall meet for informational purposes on a
          quarterly basis, rotating such meetings so that one is held via
          teleconference in one quarter and the second is held in person the
          next quarter, each such meeting to be held at a mutually agreeable
          time, to review the progress of each Work Plan, the results of such
          work and studies remaining to be completed under the Work Plan, as the
          same shall exist from time to time. In the event any such personal
          meeting is not held at Abbott Park, DAS shall reimburse Abbott for the
          reasonable travel and lodging expenses incurred by up to three (3)
          Abbott personnel to attend the meeting. Each meeting shall include
          review of the status of Patents and of any proposed studies of
          Compound. DAS will provide Abbott with summaries of the data generated
          under each Work Plan. In the event either party believes that it would
          be beneficial to meet less frequently than quarterly, or that it would
          be beneficial to end the practice of such meetings prior to the First
          Commercial Sale, then such party shall inform the other party of its
          desires, and, if the other party agrees, the parties shall then
          establish a mutually agreeable meeting schedule.

     4.3  CLINICAL DEVELOPMENT:

          (a)  DAS shall use commercially reasonable efforts to develop the
               Compound for at least three (3) indications of Pharmaceutical
               Uses. As of the Effective Date, the parties acknowledge that only
               cocaine abuse and Parkinson's Disease are recognized indications
               for the Compound. DAS shall have sole responsibility for
               designing, conducting and paying for the

[******] Confidential Treatment Requested. The confidential portions have
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               cost of the clinical development of Product and shall use
               commercially reasonable efforts to diligently conduct such
               clinical development as set forth below. Except as set forth in
               SECTION 3.2 above, Abbott hereby agrees that it shall not
               undertake any research or development related to Pharmaceutical
               Uses of the Compound during the Term, except as may be necessary
               following the license granted to Abbott under SECTION 4.8 in the
               event of a termination of this Agreement under SECTIONS 8.2, 8.3
               or 8.4, or a partial termination of this Agreement under SECTION
               4.3(c).

          (b)  After successfully completing formulation, bioavailability and
               delivery work for the first indication of Pharmaceutical Uses,
               DAS shall use commercially reasonable efforts to develop two (2)
               additional indications of Pharmaceutical Uses. DAS shall be
               obligated to commence development of the second such indication
               within two (2) years of commencing development of the first
               indication. Subject to DAS's reasonable determination of the
               commercial viability of a third indication and Abbott's rights
               under SECTION 4.3(c) below, DAS shall be obligated to commence
               development of the third such indication within two (2) years of
               commencing development of the second indication. For purposes of
               this SECTION 4.3(b), development of an indication shall be deemed
               to have commenced upon enrollment of the first subject in the
               first clinical study for an indication using the formulation
               selected for clinical development.

          (c)  In the event DAS breaches a material obligation under this
               Agreement or under a Work Plan, Abbott may then advise DAS that
               Abbott believes that DAS has breached such material obligation
               and that Abbott is adversely impacted thereby. Upon so advising
               DAS, Abbott may initiate an alternative dispute resolution
               procedure ("ADR") as set forth in EXHIBIT C, and request the ADR
               to rule upon whether DAS has breached any such material
               obligation. In the event that the neutral party to such ADR
               renders a ruling that DAS has breached such material obligation
               and that Abbott was adversely impacted thereby, and DAS fails to
               comply with the terms of the neutral's ruling within the time
               specified therein for compliance, or if such compliance cannot be
               fully achieved by such date, DAS has failed to commence
               compliance and/or has failed to use diligent efforts to achieve
               full compliance as soon thereafter as is reasonably possible,
               then Abbott's sole remedy shall be (i) the right to terminate
               this Agreement and the licenses granted hereunder, and to obtain
               from DAS a license to Improvements under SECTION 4.8; or (ii) if,
               at the time Abbott initiates the ADR, the ADR only alleges DAS's
               failure to develop the Product for some, but not all of those
               indications, then Abbott shall only be entitled to a partial
               termination of this Agreement and the licenses granted hereunder
               as to those Product indications for which failure to develop is
               alleged and determined by the ADR, and shall obtain from DAS a
               license to Improvements under SECTION 4.8 as to Improvements only
               with respect to such Product indications, with no effect on DAS's
               rights hereunder for those Product indications and Improvements
               that the

[******] Confidential Treatment Requested. The confidential portions have
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               neutral party has not declared have not been adequately developed
               by DAS hereunder.

     4.4  COMMERCIALIZATION: DAS shall use commercially reasonable efforts to
          develop and commercialize the Product in at least the following major
          countries: United States, Canada, Germany, France, U.K., Italy and
          Spain (each a "Major Country"), at least three (3) additional European
          countries, at least two (2) Latin American countries, and Japan, using
          at least that level of effort it would use with similar compounds in
          its portfolio, provided that DAS's marketing analyses support the
          profitability of Product commercialization in any such country. In the
          event that DAS elects not to market in a particular country(ies),
          either directly or through third parties, Abbott shall have the right,
          upon notice to DAS, to market, either directly or through third
          parties, the Product in each such country, by paying to DAS the same
          royalty to which Abbott would otherwise be entitled if DAS was
          marketing the Product in such country. DAS agrees to provide Product
          to Abbott for sale in each such country at the same cost (as evidenced
          by DAS's internal records) incurred by DAS in procuring or
          manufacturing Product for its own sales. If there is any material
          disagreement between the parties concerning whether commercially
          reasonable efforts towards commercialization have been made with
          respect to a particular indication after Regulatory Approval in a
          country, then the matter may be submitted to ADR where remedies for
          failure to expend such efforts could include a requirement to expend
          additional efforts to make up for any failures, damages and/or
          termination of the license rights in the applicable country, unless
          DAS chooses to undertake such activities and expenses as needed to
          correct the failure.

     4.5  MARKETING: DAS shall have sole responsibility for marketing Product,
          including entering into any co-marketing and/or co-promotion
          arrangements. DAS shall distribute all Product samples in the United
          States in accordance with the Prescription Drug Marketing Act.

     4.6  MANUFACTURING: DAS and its Affiliates shall have sole responsibility
          for manufacturing Product or having Product manufactured for it by a
          third party manufacturer. However, during the three (3) month period
          following the Effective Date, DAS will negotiate in good faith
          exclusively with Abbott with respect to the manufacture of the Product
          for clinical and commercial supply. Thereafter, in the event DAS
          negotiates terms and conditions with a third party manufacturer of
          Product, DAS shall, prior to executing a definitive agreement with
          such third party, provide Abbott with a summary of the material terms
          and conditions and allow Abbott the opportunity to meet or beat such
          terms and conditions. If Abbott fails to meet or beat such terms and
          conditions within twenty-one (21) days of its receipt, DAS shall be
          free to execute a definitive agreement for the manufacture and supply
          of Product with such third party.

     4.7  SUBLICENSING:

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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          (a)  During the two (2) year period following the Effective Date, DAS
               may sublicense to unrelated third parties its rights to one or
               more Product indications under this Agreement, only with Abbott's
               prior written consent, which consent shall not be unreasonably
               withheld. After such two year period, DAS may sublicense to
               unrelated third parties its rights to one or more Product
               indications under this Agreement without obtaining Abbott's prior
               written consent. Each sublicense shall be in writing and shall
               include provisions acknowledging that such sublicense is subject
               to the license granted DAS under this Agreement, that each
               sublicensee shall make reports and keep and maintain records of
               sales to at least the same extent as required under this
               Agreement, allowing Abbott the same access and audit rights
               permitted under this Agreement, and that such sublicense shall be
               automatically terminated upon termination of this Agreement. DAS
               shall remain primarily liable for the performance of
               sublicensees. DAS shall provide Abbott with a copy of each
               sublicense agreement.

          (b)  All consideration received by DAS as a result of each sublicense
               of its rights under this Agreement and any sub-sublicense
               agreement (including, but not limited to fees, payments,
               milestones, royalties, etc.) (collectively, the "SUBLICENSE
               CONSIDERATION") shall be divided between DAS and Abbott as
               follows:

               (i)  For any sublicense executed between the Effective Date
                    and the one year anniversary thereof, the Sublicense
                    Consideration shall be shared [******] to Abbott and
                    [******] to DAS, regardless of when paid to DAS under
                    the sublicense.

              (ii)  For any sublicense executed after the first anniversary
                    of the Effective Date but on or before the date on which
                    the first NDA for the first Product indication is filed,
                    the Sublicense Consideration shall be shared [******] to
                    DAS and [******] to Abbott, regardless of when paid to
                    DAS under the sublicense.

             (iii)  For any sublicense executed after the date on which the
                    first NDA for the first Product indication is filed, but
                    prior to the First Commercial Sale, the Sublicense
                    Consideration shall be shared [******] to DAS and [******]
                    to Abbott, regardless of when paid to DAS under the
                    sublicense.

              (iv)  For any sublicense executed after the First Commercial
                    Sale, but prior to the fifth (5th) anniversary of the
                    First Commercial Sale, the Sublicense Consideration shall
                    be shared [******] to DAS and [******] to Abbott,
                    regardless of when paid to DAS under the sublicense.

               (v)  For any sublicense executed after the fifth (5th)
                    anniversary of the First Commercial Sale, the Sublicense
                    Consideration shall be shared [******] to DAS and [******]
                    to Abbott.

          (c)  Furthermore, the amount of such Sublicense Consideration
               payable to Abbott under SECTION 4.7(b) above shall be reduced
               (or credited) by the amount DAS receives from all sublicenses
               as reimbursement for actual and reasonable research and
               development costs incurred by DAS in its evaluation and
               development of the Compound, subject to a cap of [******],
               which total costs shall be allocated and deducted ratably over
               the period during which DAS is receiving royalty payments from
               sublicenses. Such research and development costs shall consist
               of those customary costs to perform a clinical protocol which
               are documented and are payable upon receipt of a signed
               clinical study report. All research and development costs for
               which reimbursement is requested by DAS shall be measurable
               and are subject to Abbott's audit rights under SECTION 5.7(c).

          (d)  Notwithstanding anything to the contrary contained in this
               SECTION 4.7, no sublicense or sub-sublicense may be entered into
               by DAS without Abbott's prior written approval, which may be
               withheld by Abbott in its

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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<PAGE>

               sole discretion, if such sublicense would result in [******]. For
               example, if [******].

     4.8  IMPROVEMENTS: All Improvements and all new patents which relate to the
          Compound or the Product which come into existence during the Term and
          which relate to or are derived from work done by or for DAS or their
          Affiliates or sublicensees relating to the Compound without any
          contribution by Abbott, its Affiliates, contractors, or agents, shall
          be deemed the property of DAS. Provided, however, in the event this
          Agreement is terminated by Abbott for any reason, as set forth in
          ARTICLE 8, or is partially terminated by Abbott as set forth in
          SECTION 4.3(c), all such Improvements shall be exclusively licensed to
          Abbott solely for use with the Compound and Product on a worldwide,
          royalty-free, paid-up basis, and DAS retains all rights in and to any
          such Improvements for any and all other uses.

5.   EXECUTION FEE, MILESTONE PAYMENTS AND ROYALTIES.

     5.1  EXECUTION FEE. DAS shall pay to Abbott Four Hundred Thousand
          Dollars ($400,000) on the Effective Date.

     5.2  MILESTONE PAYMENTS (FIRST SUBSTANCE ABUSE INDICATION): DAS shall make
          the following milestone payments to Abbott for the first Substance
          Abuse Indication for the Product within [******], regardless of
          whether or not DAS has sublicensed any of its rights under this
          Agreement:

          (a)  FIRST MILESTONE PAYMENT: [******].

          (b)  SECOND MILESTONE PAYMENT: [******].

          (c)  THIRD MILESTONE PAYMENT: [******].

          (d)  FOURTH MILESTONE PAYMENT: [******].

     5.3  MILESTONE PAYMENTS (PARKINSON'S INDICATION): DAS shall make the
          following milestone payments to Abbott for the [******]

          (a)  FIRST MILESTONE PAYMENT: [******].

          (b)  SECOND MILESTONE PAYMENT: [******].

          (c)  THIRD MILESTONE PAYMENT: [******].

          (d)  FOURTH MILESTONE PAYMENT: [******].

     5.4  MILESTONE PAYMENTS [******] DAS shall make the following milestone
          payments to Abbott for the first Non-Parkinson's Disease and
          Non-Substance Abuse Indication for the Product [******] occurrence of
          the following events, regardless of whether or not DAS has sublicensed
          any of its rights under this Agreement:

[******] Confidential Treatment Requested. The confidential portions have
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          (a)  FIRST MILESTONE PAYMENT: [******]

          (b)  SECOND MILESTONE PAYMENT: [******]

          (c)  THIRD MILESTONE PAYMENT: [******]

          (d)  FOURTH MILESTONE PAYMENT: [******]

     5.5  MILESTONE PAYMENTS (OTHER INDICATIONS): [******]

     5.6  SALES MILESTONES:

          (a)  Upon the first attainment of [******] of all Products in a
               calendar year of [******] payment is otherwise due.

          (b)  Upon the first attainment of [******] of all Products in a
               calendar year of [******]

          (c)  For purposes of calculating Net Sales of all Products under this
               SECTION 5.6 for the one-time payment of sales milestones, Net
               Sales shall include the combined sales of Products by DAS, its
               Affiliates, their contract sales forces and all sublicensees and
               their contract sales forces.

     5.7  ROYALTY PAYMENTS:

          (a)  ROYALTY RATE AND ROYALTY PERIOD: Beginning with the First
               Commercial Sale by DAS, any Affiliates of DAS, or any contract
               sales force of DAS or its Affiliates, DAS shall pay to Abbott
               a royalty on annual aggregate worldwide Net Sales of all
               Product for all Pharmaceutical Uses in accordance with the
               following schedule:

<TABLE>
<CAPTION>
          ANNUAL NET SALES            ROYALTY
<S>                                 <C>
          [******]                    [******]
          [******]                    [******]
          [******]                    [******]
          [******]                    [******]
</TABLE>

          If DAS is required to pay royalties in excess of [******] of its
          annual Net Sales of Product to any third party in order to develop
          Product, such third party royalty payments in excess of [******]
          shall be shared equally by DAS and Abbott, up to an additional
          [******] and Abbott's share thereof (up to a maximum of [******]
          shall be credited accordingly against royalty payments due to
          Abbott hereunder if annual Net Sales of Product in a calendar year
          exceed [******] provided, however, that Abbott's liability
          hereunder for such annual royalty credits shall not exceed [******]
          of annual Net Sales.

          For example, if DAS is obligated to make third party royalty
          payments equal to [******] of annual Net Sales, DAS shall be solely
          responsible for the first [******], the next [******] shall be
          shared equally by DAS and Abbott, and Abbott's share [******] shall
          be credited dollar for dollar against royalty payments due to Abbott
          hereunder, if and only if, annual Net Sales in such calendar year
          are greater than [******]. The remaining balance of [******] of
          third party royalties shall by DAS' sole responsibility.

          The obligation of DAS to pay a royalty to Abbott shall be on a
          country-by-country basis and shall continue with respect to Product
          manufactured or sold in a country until such time as the last
          Patent included in the Abbott Technology covering such Product has
          expired and/or is invalidated in such country ("ROYALTY PERIOD").

     (b)  REDUCED ROYALTY PERIOD: Upon the end of the Royalty Period in any
          country of the Territory on a country-by-country basis, DAS shall
          have an exclusive, perpetual license under Abbott's Technology in
          such country of the Territory, with all of the rights granted under
          Article 2 hereof, except that, for so long as Product continues to
          be sold in such country by DAS, DAS shall pay to Abbott a reduced
          royalty equal to [******] of the royalty that would otherwise be
          due during the Royalty Period (the "REDUCED ROYALTY PERIOD").

          The royalty payable for the Reduced Royalty Period shall be
          calculated by (i) adding total [******] in all countries
          wherein a royalty (full or reduced) is payable hereunder; (ii)
          taking that portion of [******] which are attributable to countries
          under a reduced royalty and multiplying such amount by the product
          of the applicable royalty rate times [******]; (iii) taking that
          portion of [******] which are attributable to countries under a
          full royalty rate and multiplying such amount by the [******]; and
          (iv) adding the products obtained in (ii) and (iii) above to
          determine the total amount of royalty payable.

          For example, if [******]:

     (i)  [******]

[******] Confidential Treatment Requested. The confidential portions have
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          (ii)  [******]

          (iii) [******]

          (iv)  [******]

     (c)  ROYALTY REPORTS AND PAYMENTS: Beginning with the [******]. Each report
          shall be accompanied by [******]. In the event that conversion from
          foreign currency is required in calculating a royalty payment
          hereunder, the exchange rate used shall be the ratio in effect at the
          end of the last business day of the applicable quarter for which
          royalties are calculated, as reported by THE WALL STREET JOURNAL, or a
          substantially similar global publication if THE WALL STREET JOURNAL is
          no longer published.

     (d)  BOOKS AND RECORDS/AUDIT RIGHTS: DAS shall keep books and records
          accurately showing all Products manufactured, used or sold under the
          terms of this Agreement. The relevant portions of such books and
          records shall be open to inspection by representatives of Abbott, at
          Abbott's cost, solely for the purposes of determining the correctness
          of the royalties payable under this Agreement. Such audit, conducted
          no more than one time per calendar year, shall be during normal
          business hours after reasonable advance notice and subject to suitable
          confidentiality provisions. In the event an audit shows a deficiency
          to be due, [******]. If the audit shows that an excess was paid, DAS
          shall be entitled to deduct the amount of such excess from the payment
          due for the next calendar quarter. Such books and records shall be
          preserved for a period of at least three (3) years after the date of
          the royalty payment to which they pertain, and no audit may be
          conducted with respect to royalties due in any calendar year that is
          more than two (2) years preceding the calendar year in which the audit
          is being conducted. Books and records for a given calendar year may
          only be audited once.

     (e)  WITHHOLDING TAXES ON ROYALTIES: Where any sum due to be paid to Abbott
          hereunder is subject to any withholding or similar tax, the parties
          shall use all reasonable efforts to do all such acts and things and to
          sign all such documents as will enable them to take advantage of any
          applicable double taxation agreement or treaty. In the event there is
          no applicable double taxation agreement or treaty, or if an applicable
          double taxation agreement or treaty reduces but does not eliminate
          such withholding or similar tax, DAS shall pay such withholding or
          similar tax to the appropriate government authority, deduct the amount
          paid from the amount due Abbott and secure and send to Abbott the best
          available evidence of such payment sufficient to enable Abbott to
          obtain a deduction for such withheld taxes or obtain a refund thereof.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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<PAGE>

6.   REPRESENTATIONS/WARRANTIES.

     6.1  REPRESENTATIONS AND WARRANTIES OF ABBOTT: Abbott represents and
          warrants that it is duly organized, validly existing and in good
          standing under the laws of Illinois, that it has full corporate power
          and authority to enter into this Agreement and to carry out its
          provisions, and that there are no outstanding agreements, assignments
          or encumbrances in existence that are inconsistent with the provisions
          of this Agreement. Abbott further represents and warrants that it is
          duly authorized to execute and deliver this Agreement and to perform
          its obligations hereunder and that the execution, delivery and
          performance of this Agreement by it does not require the consent,
          approval or authorization of or notice, filing or registration with
          any governmental or regulatory agency.

     6.2  REPRESENTATIONS AND WARRANTIES OF DAS: DAS represents and warrants
          that it is duly organized, validly existing and in good standing under
          the laws of California, that it has full corporate power and authority
          to enter into this Agreement and to carry out its provisions, and that
          there are no outstanding agreements, assignments or encumbrances in
          existence that are inconsistent with the provisions of this Agreement.
          DAS further represents and warrants that it is duly authorized to
          execute and deliver this Agreement and to perform its obligations
          hereunder, and that the execution, delivery and performance of this
          Agreement by it does not require the consent, approval or
          authorization of or notice, filing or registration with any
          governmental agency or Regulatory Authority.

     6.3  INDEMNIFICATION BY DAS: DAS shall indemnify and hold Abbott, its
          Affiliates and their directors, officers, employees and agents
          harmless from and against any and all liabilities, actions, suits,
          claims, demands, prosecutions, damages, costs, expenses or money
          judgments finally awarded (including reasonable legal fees)
          (collectively, "LIABILITIES") incurred by or instituted or rendered
          against Abbott to the extent such Liabilities result from a third
          party claim arising from the willful misconduct or the negligent acts
          or omissions of DAS or its Affiliates or DAS's material breach of this
          Agreement, except to the extent such third party claims arise out of
          the gross negligence or willful misconduct of Abbott, its Affiliates
          and their directors, officers, employees and agents, and provided that
          Abbott gives DAS prompt notice in writing of any such claim or lawsuit
          and permits DAS to undertake sole control of the defense and
          settlement thereof at DAS's expense. In any such claim or lawsuit:

          (a)  Abbott will cooperate in the defense by providing access to
               witnesses and evidence available to it. Abbott shall have the
               right to participate, at its expense, in any defense to the
               extent that in its reasonable judgment Abbott may be prejudiced
               by DAS's sole defense thereof.

          (b)  With respect to this Agreement, Abbott shall not settle, offer to
               settle or admit liability in any claim or suit in which Abbott
               intends to seek

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                       16
<PAGE>

               indemnification by DAS without the written consent of a duly
               authorized officer of DAS.

     6.4  REPORTABLE OCCURRENCES: Each party warrants that it shall advise the
          other promptly of any occurrence which is reported or reportable by it
          to the Regulatory Authorities relating in any way to the Compound or
          the Product.

     6.5  LIMITATION: EXCEPT FOR THE EXPRESS WARRANTIES IN THIS ARTICLE 6,
          NEITHER PARTY MAKES ANY WARRANTIES, EXPRESS OR IMPLIED, IN FACT OR BY
          OPERATION OF LAW, STATUTORY OR OTHERWISE. EACH PARTY SPECIFICALLY
          DISCLAIMS ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
          PARTICULAR PURPOSE. EXCEPT FOR VIOLATIONS OF ARTICLE 7 AND AMOUNTS
          FINALLY AWARDED FOR INDEMNIFICATION FOR THIRD PARTY LIABILITIES UNDER
          SECTION 6.3, NEITHER PARTY SHALL BE LIABLE TO THE OTHER PARTY HERETO
          OR TO ANY THIRD PARTY FOR ANY SPECIAL, CONSEQUENTIAL, EXEMPLARY OR
          INCIDENTAL DAMAGES (INCLUDING LOST OR ANTICIPATED PROFITS RELATING TO
          THE SAME) ARISING FROM ANY CLAIM RELATING TO THIS AGREEMENT, WHETHER
          SUCH CLAIM IS BASED ON CONTRACT, TORT (INCLUDING NEGLIGENCE) OR
          OTHERWISE, EVEN IF AN AUTHORIZED REPRESENTATIVE OF SUCH PARTY IS
          ADVISED OF THE POSSIBILITY OR LIKELIHOOD OF SAME.

7.   CONFIDENTIALITY AND NON-DISCLOSURE.

     7.1  NONDISCLOSURE: Neither party shall use or disclose any Confidential
          Information received by it from the other party pursuant to this
          Agreement without the prior written consent of the other. This
          obligation will continue for a period of seven (7) years after
          termination of this Agreement or expiration of the Term, whichever is
          earlier. The parties recognized in SECTION 3.2 of this Agreement that
          Abbott may be utilizing Compound, Process Technology and Abbott
          Technology in certain limited circumstances, including, but not
          limited to, non-Pharmaceutical Uses and for internal research
          purposes. Abbott shall be permitted to disclose information pertaining
          to the Compound, the Abbott Technology and the Process Technology in
          such circumstances only if the recipient of such information is under
          a duty of confidentiality to Abbott, and further, provided that no
          such disclosure of such information shall be made for Pharmaceutical
          Uses, nor shall Confidential Information of DAS be disclosed.

     7.2  RESTRICTION: Each party shall restrict dissemination of Confidential
          Information to those of its employees, contractors, agents and
          sublicensees (if any) who have an actual need to know and have a legal
          obligation to protect the confidentiality of such Confidential
          Information. All Confidential Information disclosed by one party to
          the other shall remain the sole property of the disclosing party and
          neither party shall obtain any right of any kind to the Confidential
          Information disclosed, except as granted under this Agreement.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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     7.3  RESTRICTION EXEMPTIONS: Nothing contained in this ARTICLE 7 shall be
          construed to restrict the parties from using or disclosing
          Confidential Information solely to the extent and solely as required:

          (a)  for regulatory, tax or customs reasons;

          (b)  for audit purposes;

          (c)  by court order or other governmental order or request; or

          (d)  to perform acts permitted by this Agreement, including (i)
               disclosure by DAS to third parties undertaking feasibility and
               evaluation studies, clinical trials and the like on behalf of
               DAS, so long as such third parties are under a legal obligation
               to DAS to protect the confidentiality of such Confidential
               Information, or (ii) disclosure by DAS in connection with the
               marketing and commercial sale of Product, to the extent required
               by law.

8.   TERM AND TERMINATION.

     8.1  This Agreement shall continue in effect unless and until terminated
          as provided in this SECTION 8 or in SECTIONS 4.3 or 4.4. Upon the
          end of the Royalty Period in any country of the Territory, DAS
          shall have an exclusive, perpetual and irrevocable license under
          Abbott's Technology, with all of the rights granted under ARTICLE 2
          hereof, and without any further obligation to Abbott, except for
          the payment obligations accruing prior to such date and except for
          any obligation to pay a reduced royalty for the Reduced Royalty
          Period, as provided in SECTION 5.7(b) hereof.

     8.2  If DAS determines in its reasonable scientific and commercial judgment
          that the Compound does not have an acceptable profile or a reasonable
          likelihood of commercial success, or that it is economically or
          technically impractical for DAS to continue developing and marketing
          the Product, DAS shall have the right to terminate this Agreement upon
          ninety (90) days written notice, at the end of which the termination
          shall be effective. Upon such termination DAS shall pay all payments,
          milestones or royalties which may have become due prior to the
          effective date of such termination, and DAS shall assign and Abbott
          shall be entitled to retain for its own use, all studies and
          information relating to the Compound and shall be granted a license to
          all Improvements as set forth in SECTION 4.8 hereof.

     8.3  Either party may terminate this Agreement by giving to the other party
          prior written notice of not less than thirty (30) days in the case of
          a monetary breach and of not less than ninety (90) days in the event
          the other party shall commit a non-monetary material breach of this
          Agreement, and such breaching party shall fail to cure, or commence
          action to cure, such breach during such thirty (30) or ninety (90) day
          period, as applicable. In the case of a non-monetary breach, the cure
          period may be extended for such longer period as may reasonably be
          necessary if cure is not reasonably possible within the initial ninety
          (90) day period, provided the breaching party continues its diligent
          efforts to cure. No

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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<PAGE>

          such cancellation and termination shall release the breaching party
          from any obligations hereunder incurred prior thereto. In the event of
          a dispute whether a material breach has occurred, the existence of
          material breach shall be determined using the ADR set forth in EXHIBIT
          C. A party's right to terminate this Agreement shall only apply if the
          breaching party fails to cure such breach in the manner required by
          the final judgment of the ADR hearing. In the event that this
          Agreement is terminated for DAS's material breach, Abbott shall be
          entitled to retain for its own use all funds previously paid by DAS,
          together with all studies, information and Improvements generated
          hereunder. In the event that this Agreement is terminated for Abbott's
          material breach, DAS shall not be liable for payments not yet due and
          payable under ARTICLE 5 hereof, and DAS shall be entitled to retain
          for its own use all studies, information and Improvements generated
          hereunder.

     8.4  Either party may terminate this Agreement on thirty (30) days notice
          if the other party passes a resolution or the court makes an order for
          its winding up; or has a receiver or administrator appointed over its
          business or all of its assets; or is or becomes bankrupt; or ceases
          its business operations. In the event that this Agreement is
          terminated under this SECTION 8.4 subject to the other terms of this
          Agreement, the terminating party shall be entitled to retain for its
          own use all studies, information and Improvements (subject to the
          license set forth in SECTION 4.8 as it concerns Abbott) generated
          hereunder. Notwithstanding the bankruptcy or insolvency of Abbott or
          the impairment of performance by Abbott of its obligations under this
          Agreement as a result of bankruptcy or insolvency of Abbott, DAS shall
          be entitled to retain the licenses granted herein, without any further
          obligation to Abbott other than the payment obligations under ARTICLE
          5.

     8.5  Termination of this Agreement shall be without prejudice to any rights
          of either party against the other which may have accrued up to the
          date such termination becomes effective.

     8.6  All causes of action accruing to either party under this Agreement
          shall survive expiration or termination of this Agreement for any
          reason.

     8.7  Upon any termination or expiration of this Agreement, each party shall
          promptly return to the other party all written Confidential
          Information, and all copies thereof (retaining one copy of the
          Confidential Information of the other in its confidential files for
          archival purposes only), which is not covered by a paid-up license or
          other rights specified herein surviving such termination or
          expiration.

9.   INFRINGEMENT OF PATENTS BY THIRD PARTY. In the event of an actual or
suspected infringement of a Patent by a third party, the following shall
apply:

     9.1  NOTICE: Each party shall give the other written notice if one of them
          becomes aware of any infringement by a third party of any Patent. Upon
          notice of any such infringement, the parties shall promptly consult
          with one another with a view toward reaching agreement on a course of
          action to be pursued.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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     9.2  DAS'S RIGHT TO BRING INFRINGEMENT ACTION:

          (a)  DAS ELECTION: If a third party infringes any Patent, DAS shall
               have the first right, but not the obligation, to institute and
               prosecute an action or proceeding to abate such infringement and
               to resolve such matter by settlement or otherwise.

               (i)  DAS shall notify Abbott of its intention to bring an action
                    or proceeding prior to filing the same and in sufficient
                    time to allow Abbott the opportunity to discuss with DAS the
                    choice of counsel for such matter. DAS shall keep Abbott
                    timely informed of material developments in the prosecution
                    or settlement of such action or proceeding. DAS shall be
                    responsible for all fees and expenses of any action or
                    proceeding against infringers which DAS initiates. Abbott
                    shall cooperate fully at its expense by joining as a party
                    plaintiff if reasonably requested to do so by DAS or if
                    required to do so by law to maintain such action or
                    proceeding and by executing and making available such
                    documents as DAS may reasonably request. Abbott may be
                    represented by counsel in any such legal proceedings, at
                    Abbott's own expense.

              (ii)  If DAS elects not to exercise such first right, Abbott shall
                    have the right, at its discretion, to institute and
                    prosecute an action or proceeding to abate such infringement
                    and to resolve such matter by settlement or otherwise. DAS
                    shall cooperate fully by joining as a party plaintiff if
                    reasonably requested to do so by Abbott or if required to do
                    so by law to maintain such action and by executing and
                    making available such documents as Abbott may reasonably
                    request. DAS may be represented by counsel in any such
                    action, at its own expense.

          (b)  DAS USE OF PROCEEDS: All amounts of every kind and nature
               recovered from an action or proceeding of infringement brought by
               DAS shall belong to DAS, and shall be used first to reimburse DAS
               for its documented and actual costs of prosecution, including
               attorneys' fees, expert fees and all other related expenses,
               second to reimburse Abbott for its documented and actual costs if
               it is represented by counsel in the proceeding, and the balance
               shall thereafter be considered Net Sales under this Agreement and
               subject to royalty payments under SECTION 5.7.

          (c)  ABBOTT'S USE OF PROCEEDS: All amounts of every kind and nature
               recovered from an action or proceeding of infringement brought by
               Abbott shall belong to Abbott, and shall first be used to
               reimburse Abbott for its documented and actual costs of
               prosecution, second to reimburse DAS for its documented and
               actual costs if it is represented by counsel in the proceedings,
               and the balance shall belong to Abbott.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

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10.  INFRINGEMENT OF THIRD PARTY RIGHTS; DAS DEFENSE OF SUIT: If Abbott, its
Affiliates, DAS, its Affiliates, sublicensees, distributors or other customers
are sued or threatened with suit in the Territory by a third party alleging
infringement in one or more countries of the Territory of patents or other
intellectual property rights that are alleged to cover the manufacture, use,
sale, import, export or distribution of one or more Products, Abbott or DAS,
whichever is relevant, will promptly notify the other in writing and provide a
copy of the lawsuit or claim. DAS shall control the defense in any such claim or
suit. If DAS expends any amounts in connection with any third party claim of
infringement or misappropriation, or is required to pay a royalty or other
amount to a third party for the manufacture, use, sale, import, export or
distribution of one or more Products in the Territory as a result of a final
judgment or settlement, such amounts shall be fully deductible by DAS from the
royalties payable and accruing to Abbott thereafter under SECTION 5.7, but only
where such claim, judgement or settlement arises out of DAS's practice of a
Patent, the Process Technology or use of the Abbott Technology. Abbott shall
fully cooperate with DAS in the defense of any such action at Abbott's expense.
DAS shall have the right to settle any such suit, including the right to grant
one or more sublicenses, with the prior written approval, which approval shall
not unreasonably be withheld, provided that DAS shall not otherwise have the
right to surrender, limit or adversely affect any rights to the Patents.

11.  Patent Prosecution and Maintenance; Patent Costs; Patent Term Extension.

     11.1 DISCLOSURE OF PATENTS/APPLICATIONS TO DAS: Within thirty (30) days
          following the Effective Date, Abbott shall disclose to DAS the
          complete text of, and all other information in its possession or
          control directly related to (a) all patent applications included in
          the Patents filed anywhere in the Territory; and (b) all patents
          included in the Patents as well as all information in Abbott's, its
          Affiliates and its patent counsel's possession concerning the
          institution or possible institution of any interference, opposition,
          reexamination, reissue, revocation, nullification or any official
          proceeding involving an issued patent included in the Patents anywhere
          in the Territory.

     11.2 PROSECUTION AND MAINTENANCE: Abbott shall be solely responsible for
          the preparation, filing, prosecution and maintenance of the Patents
          and Process Technology patents in Abbott's name, including oppositions
          and interferences, subject to DAS's right to assume such duties in the
          event Abbott reasonably fails to adequately prepare, file, prosecute
          and maintain the Patents and Process Technology patents. Abbott and
          DAS shall consult and cooperate with each other, and Abbott shall keep
          DAS reasonably informed, with respect to the prosecution and
          maintenance of the Patents and Process Technology patents hereunder.
          Abbott will provide DAS with copies of all material documents received
          or prepared by Abbott in the prosecution and maintenance of the
          Patents and Process Technology patents. Abbott shall provide copies in
          a timely manner to allow DAS an opportunity, if it so elects, to
          review and comment on Abbott's proposed patent strategy. Abbott shall
          invoice DAS and DAS shall promptly reimburse Abbott for one-half of
          all reasonable direct prosecution and maintenance costs (including but
          not limited to, outside attorneys' and translation fees) incurred by
          Abbott for all of the Patents and Process Technology patents after the
          Effective Date.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                       21
<PAGE>

     11.3 PATENT EXTENSIONS: DAS shall have the right and sole responsibility
          for obtaining patent term extensions under the provisions of 35 USC
          Section 156 for any U.S. Patent and for non-U.S. Patents under
          similar provisions of law of other countries involving a Product
          which has obtained Regulatory Approval.

12.  TRADEMARK: DAS may select any Trademark or Trademarks for the Product in
the Territory. All costs related to the selection and maintenance of the
Trademark(s) shall be borne by DAS. The Trademark(s) shall be owned by DAS, and
Abbott shall have no claims or rights in or to the Trademark(s).

13.  IMPROVEMENTS: All Improvements made solely by DAS and/or its Affiliates
hereunder shall be the sole and exclusive property of DAS. All Improvements made
solely by Abbott and/or its Affiliates shall become part of Abbott's Technology,
licensed exclusively to DAS with all of the rights set forth in ARTICLE 2
hereof. All Improvements made jointly by Abbott and DAS (or by their Affiliates)
hereunder shall become jointly owned, provided that to the extent that such
Improvements are owned by Abbott, they shall be included in the license granted
to DAS under ARTICLE 2 hereof. The provisions of this ARTICLE 13 are subject to
the rights of the terminating party under ARTICLE 8 hereof.

14.  MISCELLANEOUS.

     14.1 FORCE MAJEURE: If the performance by either party of any of its
          obligations under this Agreement shall be prevented by circumstances
          beyond its reasonable control which could not have been avoided by the
          exercise of reasonable diligence, then such party shall be excused
          from the performance of that obligation for the duration of the event.
          The affected party shall promptly notify the other party in writing
          should such circumstances arise, give an indication of the likely
          extent and duration thereof, and shall use commercially reasonable
          efforts to resume performance of its obligations as soon as
          practicable.

     14.2 NOTICES: Any notice required to be given or made under this Agreement
          by one of the parties hereto to the other shall be in writing, by
          personal delivery, registered U.S. mail or overnight courier,
          addressed to such other party at its address indicated below, or to
          such other address as the addressee shall have last furnished in
          writing to the addressor and shall be effective upon the date of
          receipt.

          If to DAS:         Drug Abuse Sciences, Inc.
                             330 Distel Circle
                             Suite 150
                             Los Altos, CA 94022
                             Attn:    Philippe Pouletty, M.D., CEO and Chairman

          If to Abbott:      Abbott Laboratories
                             100 Abbott Park Road
                             Dept. 309; Bldg. AP30

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                       22
<PAGE>

                             Abbott Park, IL  60064-3537
                             Attn:    Senior Vice President,
                                      Pharmaceutical Operations

          With a copy to:    Abbott Laboratories
                             100 Abbott Park Road
                             Dept. 364; Bldg. AP6D
                             Abbott Park, IL  60064-6032
                             Attn:    Senior Vice President,
                                      General Counsel and Secretary

     14.3 APPLICABLE LAW/COMPLIANCE: This Agreement shall be governed by and
          construed in accordance with the laws of the State of New York,
          excluding its conflict of laws provision. Each party hereto shall
          comply with all applicable laws, rules, ordinances, guidelines,
          consent decrees and regulations of any federal, state or other
          governmental authority.

     14.4 ENTIRE AGREEMENT: This Agreement and the attachments (Exhibits)
          contain the entire understanding of the parties with respect to the
          subject matter hereof. All express or implied agreements and
          understandings, either oral or written, heretofore made are expressly
          merged in and made a part of this Agreement. This Agreement may be
          amended, or any term hereof modified, only by a written instrument
          duly executed by both parties hereto.

     14.5 COUNTERPARTS: This Agreement may be executed in two or more
          counterparts, each of which shall be deemed an original, but all of
          which together shall constitute one and the same instrument.

     14.6 SEVERABILITY/HEADINGS: If any provision of this Agreement is deemed
          unenforceable, the remainder of the Agreement will not be affected
          and, if appropriate, the parties will attempt to replace the
          unenforceable provision with a new provision that, to the extent
          possible, reflects the parties' original intent. The captions and
          headings used in this Agreement are for reference only and are not to
          be construed in any way as terms or used to interpret the provisions
          of this Agreement.

     14.7 ASSIGNMENT: Neither party may without written approval of the other
          assign this Agreement or transfer its interest or any part thereof
          under this Agreement to any third party except that (i) either party
          may assign this Agreement without consent to a third party that
          acquires all or substantially all of the business to which this
          Agreement pertains, or, (ii) either party may assign this Agreement in
          whole or part to any Affiliate or sublicensee of that party and such
          party hereby guarantees the performance by such Affiliates and
          sublicensees.

     14.8 DISPUTE RESOLUTION: The parties hereto shall attempt to settle any
          dispute arising out of or relating to this Agreement in an amicable
          way. Except for claims for injunctive or other equitable relief, which
          may be brought in any court of

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                       23
<PAGE>

          competent jurisdiction, any controversy, claim or right of termination
          for cause which may arise under, out of, in connection with, or
          relating to this Agreement, or any breach thereof, shall be settled
          according to the Alternative Dispute Resolution provisions attached
          hereto as EXHIBIT C.

     14.9 INDEPENDENT CONTRACTOR: It is understood that both parties hereto are
          independent contractors and engage in the operation of their own
          respective businesses and neither party hereto is to be considered the
          agent of the other party for any purpose whatsoever and neither party
          has any authority to enter into any contract or assume any obligation
          for the other party or to make any warranty or representation on
          behalf of the other party. Each party shall be fully responsible for
          its own employees, servants and agents, and the employees, servants
          and agents of one party shall not be deemed to be employees, servants
          and agents of the other party for any purpose whatsoever.

    14.10 BOARD OF DIRECTOR APPROVAL: This Agreement is subject to approval of
          DAS's Board of Directors, notice of which shall be given by DAS to
          Abbott within five (5) days of the date hereof. In the event DAS fails
          to give notice within such time period, Board of Director approval
          will be deemed to have been given.

    14.11 PUBLICITY: No press release or other public announcement shall be
          made by either party concerning the execution of this Agreement or the
          fact that DAS has licensed the Compound from Abbott. Neither party
          shall use the name of the other party, its officers, the other party's
          employees and agents for purposes of any public commercial activity
          without the other party's prior written consent, except where the name
          of the other party must be disclosed as a matter of law. Should either
          party be required by law to make a disclosure, the disclosing party
          shall submit a copy of the proposed disclosure to the other party for
          review. The non-disclosing party shall have three (3) weeks to review
          and comment on the content of such disclosure. The disclosing party,
          subject to legal requirements, shall use all reasonable efforts to
          accommodate the non-disclosing party's comments. For non-routine
          matters like an emergency, special circumstance, or other situation
          where the law compels a disclosure in less than three (3) week's time,
          the non-disclosing party agrees to use commercially reasonable efforts
          to provide its review and comment in order to meet the disclosing
          party's timetable.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                       24
<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have executed this
Agreement as of the Effective Date.

ABBOTT LABORATORIES                      DRUG ABUSE SCIENCES, INC.

By:  /s/ Arthur J. Higgins               By:   /s/ Philippe Pouletty
   ---------------------------------         ---------------------------------
Name: Arthur J. Higgins                  Name: Philippe Pouletty, M.D.
     -------------------------------          --------------------------------

Its:       Senior Vice President,        Its:      Chairman and CEO
           Pharmaceutical Operations

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

<PAGE>

                                    EXHIBIT A

                                       TO
                           EXCLUSIVE LICENSE AGREEMENT
                                     BETWEEN
                               ABBOTT LABORATORIES
                                       AND
                            DRUG ABUSE SCIENCES, INC.
                           DATED AUGUST ________, 2000

                         PATENTS AND PATENT APPLICATIONS

U.S. Patent No. 5,597,832

Corresponding Pending Ex-U.S. patent applications:

<TABLE>
<CAPTION>
         Country         Application #      Filing Date
         ----------------------------------------------
<S>                        <C>              <C>
         Canada            2,159,481        03/18/1994
         EP                94912799.7       03/18/1994
         Israel            108,993          03/16/1994
         Korea             95704355         03/18/1994
         Norway            19953957         03/18/1994
         Philippines       48037            04/05/1994
         PC                PCT/US94/02894   03/18/1994
</TABLE>

Corresponding Issued Ex-U.S. patent applications:

<TABLE>
<CAPTION>
         Country           Application #    Filing Date
         ----------------------------------------------
<S>                        <C>              <C>
         Australia         6520394          03/18/1994
         China             94912799.7       03/18/1994
         Japan             108,993          03/18/1994
         Mexico            95704355         03/29/1994
</TABLE>

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-1

<PAGE>

                                    EXHIBIT B

                                       TO
                           EXCLUSIVE LICENSE AGREEMENT
                                     BETWEEN
                               ABBOTT LABORATORIES
                                       AND
                            DRUG ABUSE SCIENCES, INC.
                           DATED AUGUST _______, 2000

                                    WORK PLAN

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------
    TITLE                            DESCRIPTION                        INVESTIGATOR          DURATION     EXPECTED
                                                                                                           COMPLETION
------------------------------------------------------------------------------------------------------------------------
<S>                             <C>                                <C>                       <C>           <C>
    Proof of Concept on IV      -        [******]                       To be determined      [******]        06.01
    formulation
------------------------------------------------------------------------------------------------------------------------
    Formulation Improvement     -        [******]                  [******]                   [******]       12.01

                                                                                                             09.02
------------------------------------------------------------------------------------------------------------------------
    [******]                    -        [******]                       To Be Determined      [******]       3.03

                                -        End points: [******]
------------------------------------------------------------------------------------------------------------------------
    Pivotal Trial               -        [******]                       [******]              [******]       03.04
------------------------------------------------------------------------------------------------------------------------
    NDA Filing, US and EU                                                                     [******]       05.04
------------------------------------------------------------------------------------------------------------------------
    NDA approval US                                                                                          12.04
    NDA approval EU                                                                                          06.05
------------------------------------------------------------------------------------------------------------------------
</TABLE>

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-2
<PAGE>

                                    EXHIBIT C

                                       TO
                           EXCLUSIVE LICENSE AGREEMENT
                                     BETWEEN
                               ABBOTT LABORATORIES
                                       AND
                            DRUG ABUSE SCIENCES, INC.
                           DATED AUGUST ________, 2000

                         ALTERNATIVE DISPUTE RESOLUTION

     The parties recognize that a bona fide dispute as to certain matters may
arise from time to time during the term of this Agreement which relates to
either party's rights and/or obligations. To have such a dispute resolved by
this Alternative Dispute Resolution (ADR) provision, a party must send written
notice of the dispute to the other party for attempted resolution by good faith
negotiations between their respective presidents (or their equivalents) of the
affected subsidiaries, divisions, or business units within twenty-eight (28)
days after such notice is received (all references to "days" in this ADR
provision are to calendar days). If the matter has not been resolved within
twenty-eight (28) days of the notice of the dispute, or if the parties fail to
meet within such twenty-eight (28) days, either party may initiate an ADR
proceeding as provided herein. The parties shall have the right to be
represented by counsel in such a proceeding.

     1. To begin an ADR proceeding, a party shall provide written notice to the
other party of the issues to be resolved by ADR. Within fourteen (14) days after
receipt of such notice, the other party may, by written notice to the party
initiating the ADR, add additional issues to be resolved within the same ADR.

     2. Within twenty-one (21) days following receipt of the original ADR
notice, the parties shall select a mutually acceptable independent and neutral
third party (a "neutral") to preside in the resolution of any disputes in this
ADR proceeding. If the parties are unable to agree on a mutually acceptable
neutral within such period, either party may request the President of the CPR
Institute for Dispute Resolution (CPR), 366 Madison Avenue, 14th Floor, New
York, New York 10017, to select a neutral pursuant to the following procedures:

          (i)  The CPR shall submit to the parties a list of not less than five
               (5) candidates within fourteen (14) days after receipt of the
               request, along with a CURRICULUM VITAE for each candidate. No
               candidate shall be an employee, director, or shareholder of, or
               in any way affiliated with, either party or any of their
               subsidiaries or Affiliates.

         (ii)  Such list shall include a statement of disclosure by each
               candidate of any circumstance likely to affect his or her
               impartiality.

        (iii)   Each party shall number the candidates in order of preference
               (with the number one (1) signifying the greatest preference) and
               shall

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-3
<PAGE>

               deliver the list to the CPR within seven (7) days following
               receipt of the list of candidates. If a party believes a conflict
               of interest exists regarding any of the candidates, the party
               shall provide a written explanation of the conflict to the CPR
               along with its list showing its order of preference for the
               candidates. Any party failing to return a list of preferences on
               time shall be deemed to have no order of preference.

          (iv) If the parties collectively have identified fewer than three (3)
               candidates deemed to have conflicts, the CPR shall designate as
               neutral the candidate for whom the parties collectively have
               indicated the greatest preference. If a tie shall result between
               two candidates, the CPR may designate either candidate. If the
               parties collectively have identified three (3) or more candidates
               deemed to have conflicts, the CPR shall review the explanations
               regarding conflicts, and, in its sole discretion, may either (i)
               immediately designate as the neutral the candidate for whom the
               parties collectively have indicated the greatest preference, or
               (ii) issue a new list of not less than five (5) candidates, in
               which case the procedures set forth in subparagraphs 2(a) through
               2(d) shall be repeated.

     (b)  No earlier than twenty-eight (28) days or later than fifty-six (56)
          days after the selection, the neutral shall hold a hearing to resolve
          each of the issues identified by the parties. The ADR proceeding shall
          take place at a location agreed upon by the parties. If the parties
          cannot agree, the neutral shall designate a location other than the
          principle place of business of either party or any of their
          subsidiaries or Affiliates.

     (c)  At least seven (7) days prior to the hearing, each party shall submit
          the following to the other party and the neutral:

          (i)  a copy of all exhibits on which such party intends to rely in any
               oral or written presentation to the neutral;

         (ii)  a list of any witnesses such party intends to call at the
               hearing, and a short summary of the anticipated testimony of each
               witness;

        (iii)  a proposed ruling on each issue to be resolved, together with a
               request for a specific damage award or other remedy for each
               issue. The proposed rulings and remedies shall not contain any
               recitation of the facts or any legal arguments and shall not
               exceed one (1) page per issue.

         (iv)  a brief in support of each party's proposed rulings and remedies
               provided that the brief shall not exceed twenty (20) pages. This

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-4
<PAGE>
               page limitation shall apply regardless of the number of issues
               raised in the ADR proceeding.

          Except as expressly set forth in subparagraphs 4(a) - 4(d), no
          discovery shall be required or permitted by any means, including
          depositions, interrogations, requests for admissions, or
          production of documents.

     (d)  The hearing shall be conducted on two (2) consecutive days and shall
          be governed by the following rules:

          (i)  Each party shall be entitled to five (5) hours of hearing time to
               present its case. The neutral shall determine whether each party
               has had the five (5) hours to which it is entitled.

         (ii)  Each party shall be entitled, but not required, to make an
               opening statement, to present regular and rebuttal testimony,
               documents or other evidence, to cross examine witnesses, and to
               make a closing argument. Cross examination of witnesses shall
               occur immediately after their direct testimony, and cross
               examination shall be charged against the party conducting the
               cross examination.

        (iii)  The party initiating the ADR shall begin the hearing and, if it
               chooses to make an opening statement, shall address not only
               issues it raised but also any issues raised by the responding
               party. The responding party, if it chooses to make an opening
               statement, also shall address all issues raised in the ADR.
               Thereafter, the presentation of regular and rebuttal testimony
               and documents, other evidence, and closing arguments shall
               proceed in the same sequence.

         (iv)  Except when testifying, witnesses shall be excluded from the
               hearing until closing arguments.

          (v)  Settlement negotiations, including any statements made therein,
               shall not be admissible under any circumstances. Affidavits
               prepared for purposes of the ADR hearing also shall not be
               admissible. As to all other matters, the neutral shall have sole
               discretion regarding the admissibility of any evidence.

     (e)  Within seven (7) days following completion of the hearing, each party
          may submit to the other party and the neutral a posthearing brief in
          support of its proposed rulings and remedies, provided that such brief
          shall not contain or discuss any new evidence and shall not exceed ten
          (10) pages. This page limitation shall apply regardless of the number
          of issues raised in the ADR proceeding.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-5
<PAGE>

     (f)  The neutral shall rule on each disputed issue within fourteen (14)
          days following completion of the hearing.

     (g)  The neutral shall be paid a reasonable fee plus expenses. These fees
          and expenses, along with the reasonable legal fees and expenses of the
          prevailing party (including all expert witness fees and expenses), the
          fees and expenses of a court recorder, and any expenses for a hearing
          room, shall be paid as follows:

          (i)  If the neutral rules in favor of one party on all disputed issues
               in the ADR, the losing party shall pay 100% of such fees and
               expenses.

         (ii)  If the neutral rules in favor of one party on some issues, and
               the other party on other issues, the neutral shall issue with the
               rulings a written determination as to how such fees and expenses
               shall be allocated between the parties. The neutral shall
               allocate the fees and expenses in a way that bears a reasonable
               relationship to the outcome of the ADR, with the party prevailing
               on more issues, or on issues of greater value or gravity,
               recovering a relatively larger share of its legal fees and
               expenses.

     (h)  The rulings of the neutral and the allocation of fees and expenses
          shall be binding, nonreviewable, and nonappealable, and may be entered
          as a final judgment in any court having jurisdiction.

     (i)  Except as provided in paragraph 9 and except as to such disclosure
          which is required by applicable law or regulation, the existence of
          the dispute, any settlement negotiations, the ADR hearing, any
          submissions (including exhibits, testimony, proposed rulings, and
          briefs), and the rulings shall be deemed Confidential Information. The
          neutral shall have the authority to impose sanctions for unauthorized
          disclosure of Confidential Information.

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-6
<PAGE>

                                    EXHIBIT D

                                       TO
                           EXCLUSIVE LICENSE AGREEMENT
                                     BETWEEN
                               ABBOTT LABORATORIES
                                       AND
                            DRUG ABUSE SCIENCES, INC.
                           DATED AUGUST ________, 2000

                           PROCESS TECHNOLOGY PATENTS

U.S. Patent No. 5,659,037

Corresponding Pending Ex-U.S. patent applications:

<TABLE>
<CAPTION>
         Country           Application #    Filing Date
         ----------------------------------------------
<S>                        <C>              <C>
         Canada            2,195,676        08/03/1995
         EPC               959275660        08/03/1995
         Japan             50809696         08/03/1995
         Mexico            971221           08/03/1995
         PC                PCT/US95/09859   08/03/1995
</TABLE>

[******] Confidential Treatment Requested. The confidential portions have
been filed separately with the Securities & Exchange Commission.

                                      E-7<PAGE>
                                                                  EXHIBIT 10.23

[DAS LOGO]

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

December 27, 1999

James W. Elder
1433 Kentbrooke Drive
Ballwin, MO  63021

Re:  Employment Agreement

Dear Jim:

On behalf of DrugAbuse Sciences, I am pleased to confirm our proposal for you
to become a DrugAbuse Sciences employee. This offer is conditional upon our
completion of satisfactory referencing, 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 Senior Vice President,
Marketing and Sales, North America. As we discussed, your position is a
full-time position and your employment will commence no later than January
24, 2000 (the date your employment commences is referred to as your Start
Date.)

Your total full time base salary will be $140,000 per year until you and your
family relocate to the bay area, and increase to $150,000 per year following
an IPO, and increase to $155,000 per year following relocation, 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 upward 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 25% bonus (i.e. 25% of the
paid base salary) subject to meeting specific annual milestones defined by
DrugAbuse Sciences CEO (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 700,000 shares of common
stock, with the exercise price equal to a maximum of 10 cents per share on
your start date. These options, based on the October 1999 capitalization
table, will be subject to the terms of the then applicable Stock Option Plan,
and to the following vesting schedule: (i) 280,000 shares of the 700,000
shares would vest over four years subject to continuous employment, with
5,833 shares vesting every month for forty eight months, (subject, for any
initial vesting to have occurred, to you do not resign within the first six
months of employment); (ii) 420,000 shares of the 700,000 shares would vest
solely upon the sixth anniversary of continuous employment, subject to
potential partial acceleration at

<PAGE>

the sole discretion of the board of directors, and subject to fully and
timely achieving the following milestones:

   - For 80,000 shares: upon achieving at least $12 million of US annual net
     product sales (DAS revenue), if by 2001 (from product acquisition,
     co-promotion or co-marketing agreements);

   - For 30,000 shares: Upon Naltrel net annual US sales being at least $30
     million, if by 2003;

   - For 70,000 shares: Upon Naltrel net annual US sales being at least $50
     million, if by 2003;

   - For 100,000 shares: Upon total net annual US sales being at least $100
     million, if by 2004;

   - For 80,000 shares: Upon DAS first year of profitability (on a fully
     consolidated annual basis, audited statements);

   - For 40,000 shares: Upon DAS having received funding for at least $10
     million from new US research grant(s) (other than NIDA's 1999 Phase I/II
     grants), if by 2002;

   - For 20,000 shares: Upon DAS successful initial public offering, if by
     April 30, 2001.

You will also be eligible to participate in the employee benefits
collectively available to our employees, including medical, dental and
disability coverage. As a regular employee of the Company, you will accrue
annually a total of twelve paid and six unpaid days of vacation and be
entitled to the standard Company holidays,

You will devote your best efforts to the performance of your work 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 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. You
will not use or disclose to DrugAbuse Sciences (and DrugAbuse Sciences will
not request that you do so) confidential information and trade secrets that
you have obtained in previous employments.

If you choose not to relocate immediately, and for up to one year (or until
you relocate if sooner), the company will (i) pay the direct cost (i.e. coach
airfare through the company's travel agency) of commuting once a week between
your current residence and San Francisco, (so that you can spend a minimum of
three days per week at the Company) and (ii) pay for hotel and car rental.
You will exercise best efforts to relocate to the Bay Area within one year
from Start Date. Upon your relocation, the company will pay for direct moving
expenses for you and your family (excluding realtor fees) up to approximately
$20,000 (Should you resign within 12 months of relocation, you would
immediately reimburse $20,000 to the company). To help you relocate to the
Bay Area and purchase a house, the company will provide you a loan for
$150,000, at a low interest rate. No repayment of the loan will be due until
the second anniversary of the loan funding. You will then fully reimburse the
loan and accrued interest with fixed monthly payments over the following two
years.

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

<PAGE>

Sciences at any time, for any reason, with or without notice and with or
without cause, in your or our sole discretion. Should you be terminated
without cause and have to relocate back within your first twelve months of
employment, the company would reimburse direct relocation cost up to $20,000.
Should you be terminated without cause (only during the first five years of
employment, and only if the aggregate total value of your vested options was
lower than $140,000, based on fair market value, assuming all vested shares
were exercised), you would then be entitled, as overall severance, to monthly
payments equivalent to your start monthly base salary (i) for six months or
(ii) until you accept a new full time position, or (iii) until the value of
your vested options exceeds $140,000, whichever occurs first. A severance of
two months salary would apply upon termination without cause after the fifth
anniversary of employment.

Jim, 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.
This offer, if not accepted in writing will expire on December 28, 1999.
Changes to your employment agreement would apply only if in writing and
signed by the DrugAbuse Sciences Inc. CEO. We look forward to you becoming a
member of our team!

Sincerely,

/s/ Philippe Pouletty

Philippe Pouletty, M.D.
Chairman and CEO, DAS Inc.

I, Jim Elder, 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/ James Elder                       Date:    12/27/99
        --------------------------------            ------------------------

ATTACHMENT A
------------

I.    First year potential 25% 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)  Launching therapeutic products in the US following a product or
           business acquisition,

<PAGE>

      (2)  Having implemented a pre-marketing plan and finalized a detailed
           US marketing, launch, and phase IV plan for Naltrel, approved by
           the Board of Directors,

      (3)  Having hired a competent marketing and sales team to support
           commercial activities.

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