<PAGE>

                                                                    Exhibit 10.1

Confidential treatment has been requested for portions of this exhibit. The copy
filed herewith omits the information subject to the confidentiality request.
Omissions are designated as **. A complete version of this exhibit has been
filed separately with the Securities and Exchange Commission.


                             COLLABORATION AGREEMENT

                           dated as of April 14, 2002

                                 by and between

                               ADOLOR CORPORATION

                                       and

                               GLAXO GROUP LIMITED

<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                  Page
<S>                                                                                               <C>
ARTICLE 1        DEFINITIONS ............................................................          1

ARTICLE 2        RIGHTS AND OBLIGATIONS .................................................         16
      2.1      License Grants from Adolor to GSK ........................................         16
      2.2      License Grant from GSK to Adolor .........................................         17
      2.3      Sublicensing and Subcontracting ..........................................         18
      2.4      Trademarks and Housemarks ................................................         19
      2.5      Intellectual Property ....................................................         26
      2.6      Exclusivity ..............................................................         26
      2.7      OTC Rights ...............................................................         27

ARTICLE 3        GOVERNANCE OF DEVELOPMENT AND COMMERCIALIZATION OF PRODUCTS ............         27
      3.1      Joint Steering Committee .................................................         27
      3.2      Joint Development Committee ..............................................         30
      3.3      Joint Marketing Committee ................................................         32
      3.4      Joint Supply Committee ...................................................         34
      3.5      Minutes of Committee Meetings ............................................         36
      3.6      Expenses .................................................................         37
      3.7      Initial Coordination Efforts .............................................         37

ARTICLE 4        DEVELOPMENT OF PRODUCTS ................................................         37
      4.1      Responsibilities of the Parties ..........................................         37
      4.2      Obligations for Development ..............................................         38
      4.3      Additional Products ......................................................         38
      4.4      U.S. Development Plans ...................................................         40
      4.5      Implementation of U.S. Development Plans .................................         41
      4.6      Development Funding ......................................................         41
      4.7      Development in the ROW ...................................................         43
      4.8      Fulfillment of Obligations ...............................................         44
      4.9      Transfer of Data .........................................................         44
      4.10     Right to Audit ...........................................................         44

ARTICLE 5        CO-PROMOTION, DETAILING AND COMMERCIALIZATION ..........................         45
      5.1      U.S. Marketing Plans .....................................................         45
      5.2      Marketing Funding ........................................................         47
      5.3      Implementation of U.S. Marketing Plans ...................................         48
      5.4      Obligations for Commercialization ........................................         48
      5.5      Commercialization Responsibilities .......................................         49
      5.6      Detailing Efforts ........................................................         50
      5.7      Detailing and Marketing Requirements .....................................         51
      5.8      Sales Force Incentive Compensation for POI Products ......................         51
      5.9      Detailing Reports ........................................................         52
</TABLE>

                                        i

<PAGE>

                               TABLE OF CONTENTS
                                  (continued)

<TABLE>
<CAPTION>
                                                                                                            Page
<S>                                                                                                          <C>
      5.10     Training ..........................................................................           52
      5.11     Commercialization in the ROW ......................................................           53

ARTICLE 6             FINANCIAL PROVISIONS .......................................................           54
      6.1      Upfront Payment ...................................................................           54
      6.2      Milestone Payments ................................................................           55
      6.3      Marketing Contribution for Collaboration Products .................................           55
      6.4      Payment of Royalties on Net Sales in the ROW ......................................           57
      6.5      Payment of Royalties on Net Sales of GI Products in the United States .............           57
      6.6      Royalty Responsibilities; Net Sales Reports .......................................           58
      6.7      Reports ...........................................................................           59
      6.8      Payment Upon Expiration of the Adolor Product Promotion Term ......................           62
      6.9      GAAP ..............................................................................           62
      6.10     Currencies ........................................................................           62
      6.11     Manner of Payments ................................................................           63
      6.12     Interest on Late Payments .........................................................           63
      6.13     Tax Withholding ...................................................................           63
      6.14     Financial Records; Audits .........................................................           63

ARTICLE 7             Promotional Materials AND Samples ..........................................           64
      7.1      Promotional Materials .............................................................           64
      7.2      Samples for the United States .....................................................           66

ARTICLE 8             INFORMATION CONCERNING THE COLLABORATION Products ..........................           67
      8.1      Statements Consistent with Labeling ...............................................           67
      8.2      Medical Inquiries .................................................................           67
      8.3      Standard Operating Procedures .....................................................           68

ARTICLE 9             REGULATORY MATTERS .........................................................           68
      9.1      Communications and Meetings with Governmental Authorities .........................           68
      9.2      Filings with Governmental Authorities .............................................           70
      9.3      In the ROW ........................................................................           71
      9.4      Approval of Labeling and Promotional Materials ....................................           72
      9.5      Regulatory Information ............................................................           72
      9.6      Exchange of Drug Safety Information ...............................................           73
      9.7      Recalls Or Other Corrective Action ................................................           73
      9.8      Events Affecting Integrity or Reputation ..........................................           75
      9.9      Sharing of Regulatory Filings .....................................................           75

ARTICLE 10            ORDERS; SUPPLY AND RETURNS .................................................           75
      10.1     Orders and Terms of Sale in the United States for Adolor Products .................           75
      10.2     Orders and Terms of Sale in the United States for GI Products .....................           75
</TABLE>

                                       ii

<PAGE>

                                TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                                                             Page
<S>                                                                                                          <C>
      10.3     Orders and Terms of Sale in the ROW .............................................             76
      10.4     Misdirected Orders ..............................................................             76
      10.5     Product Returns .................................................................             76
      10.6     Supply of API Compound and Collaboration Product for Development
               of Collaboration Products .......................................................             77
      10.7     Supply of API Compound for Commercialization of Collaboration Products ..........             78
      10.8     Supply of Collaboration Products for Commercialization ..........................             79
      10.9     Shortages .......................................................................             80
      10.10    Product Suppliers ...............................................................             81
      10.11    Standard Terms of Supply ........................................................             81

ARTICLE 11            GSK PRODUCT ..............................................................             84
      11.1     GSK Product Right and License ...................................................             84
      11.2     Adolor Selection Process and Timeframe ..........................................             84
      11.3     GSK Product Agreement ...........................................................             85
      11.4     No Selected GSK Product .........................................................             85

ARTICLE 12            CONFIDENTIAL INFORMATION .................................................             86
      12.1     Confidential Information ........................................................             86
      12.2     Permitted Disclosure and Use ....................................................             86
      12.3     Publications ....................................................................             87
      12.4     Public Announcements ............................................................             87
      12.5     Confidentiality of this Agreement ...............................................             87
      12.6     Survival ........................................................................             87

ARTICLE 13            REPRESENTATIONS AND WARRANTIES; COVENANTS ................................             87
      13.1     Mutual Representations and Warranties ...........................................             87
      13.2     Additional GSK Representations and Warranties ...................................             88
      13.3     Additional Adolor Representations and Warranties ................................             89
      13.4     Covenants .......................................................................             90
      13.5     Disclaimer of Warranty ..........................................................             90

ARTICLE 14            INDEMNIFICATION ..........................................................             91
      14.1     Indemnification by GSK ..........................................................             91
      14.2     Indemnification by Adolor .......................................................             91
      14.3     Procedure for Indemnification ...................................................             92
      14.4     Assumption of Defense ...........................................................             93
      14.5     Product Liability Claims in the United States ...................................             93
      14.6     Insurance .......................................................................             94
      14.7     Limitation of Liability .........................................................             94
</TABLE>

                                       iii

<PAGE>

                               TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                                                            Page
<S>                                                                                                          <C>
ARTICLE 15            PATENT INFRINGEMENT ..........................................................         95
      15.1     Prosecution and Maintenance of Patents ..............................................         95
      15.2     Patent Infringement .................................................................         98
      15.3     Notice of Certification .............................................................         99
      15.4     Assistance ..........................................................................        100

ARTICLE 16            TERM AND TERMINATION .........................................................        100
      16.1     Term ................................................................................        100
      16.2     Extension of Adolor Product Promotion Term ..........................................        100
      16.3     Termination for Breach ..............................................................        100
      16.4     Termination for Safety Related Reasons ..............................................        100
      16.5     Termination by GSK with Respect to Adolor Products ..................................        101
      16.6     Termination by GSK With Respect to the OBD Chronic Product ..........................        102
      16.7     Termination by GSK With Respect to GI Products Other Than the OBD Chronic Product ...        103
      16.8     Termination by Adolor ...............................................................        104
      16.9     Effects of Expiration of the Adolor Product Promotion Term ..........................        106
      16.10    Effects of Expiration of the GI Product Promotion Term ..............................        107
      16.11    Effects of Expiration of the ROW Term ...............................................        108
      16.12    Effect of Termination ...............................................................        109
      16.13    Effect of Termination for Safety Related Reasons ....................................        111
      16.14    General Effects of Termination ......................................................        111

ARTICLE 17            LIMITATIONS ON PURCHASES OF EQUITY SECURITIES ................................        111
      17.1     Purchases of Equity Securities ......................................................        111
      17.2     Exceptions for Purchasing Securities of Adolor ......................................        112

ARTICLE 18            MISCELLANEOUS ................................................................        113
      18.1     Relationship of the Parties .........................................................        113
      18.2     Registration and Filing of this Agreement ...........................................        113
      18.3     Force Majeure .......................................................................        113
      18.4     Governing Law .......................................................................        114
      18.5     Dispute Resolution; Arbitration .....................................................        114
      18.6     Assignment ..........................................................................        115
      18.7     Notices .............................................................................        115
      18.8     Severability ........................................................................        117
      18.9     Headings ............................................................................        117
      18.10    Waiver ..............................................................................        117
      18.11    Entire Agreement ....................................................................        117
      18.12    No License ..........................................................................        117
      18.13    Third Party Beneficiaries ...........................................................        117
      18.14    Counterparts ........................................................................        118
</TABLE>

                                       iv

<PAGE>

                             COLLABORATION AGREEMENT

         This COLLABORATION AGREEMENT ("Agreement") dated as of April 14, 2002
                                        ---------
(the "Effective Date"), is made by and between ADOLOR CORPORATION, a Delaware
      --------------
corporation and having its principal office at 620 Pennsylvania Drive, Exton,
Pennsylvania 19341 ("Adolor"), and GLAXO GROUP LIMITED, a United Kingdom
                     ------
corporation, and having its principal office at Glaxo Wellcome House, Berkeley
Avenue, Greenford, Middlesex, UB6 0NN, United Kingdom ("GSK"). Adolor and GSK
                                                        ---
may be referred to as a "Party" or together, the "Parties".
                         -----                    -------

                                    RECITALS

         WHEREAS, Adolor is currently developing a compound known as alvimopan
for postoperative bowel dysfunction and other gastrointestinal disorders;

         WHEREAS, GSK has significant experience in the development, marketing
and promotion of pharmaceutical products and believes it can make significant
contributions to the successful development and commercialization of alvimopan;

         WHEREAS, GSK and Adolor have complementary technology, capabilities and
resources which are necessary for the development and commercialization of the
Collaboration Products;

         WHEREAS, GSK and Adolor are willing to undertake such development and
commercialization activities and investment based on the coordination of such
activities and investment provided by this Agreement similar to that of a single
entity with respect to the Collaboration Products; and

         WHEREAS, GSK and Adolor believe that a collaboration pursuant to this
Agreement for the development, promotion and commercialization of alvimopan
would be desirable and fully compatible with their respective business
objectives and provide the most effective and efficient means to ensure that the
Collaboration Products are developed and commercialized so as to maximize the
return on investment for GSK and Adolor.

         NOW, THEREFORE, in consideration of the foregoing premises and the
representations, covenants and agreements contained herein, Adolor and GSK,
intending to be legally bound, hereby agree as follows:

                                   ARTICLE 1
                                  DEFINITIONS

         For purposes of this Agreement, the following initially capitalized
terms, whether used in the singular or plural, shall have the following
meanings:

         1.1      "AAA" shall have the meaning set forth in Section 18.5.2.
                   ---

<PAGE>

         1.2  "Additional Product" means a ** Product and any Product other
               ------------------
than a POI Product, an OBD Acute Product, an OBD Chronic Product, a ** Product
or an ** Product included by the Parties pursuant to Section 4.3.

         1.3  "Adolor Housemark" means the name and logo of Adolor or an
               ----------------
Affiliate of Adolor as identified by Adolor to GSK from time to time.

         1.4  "Adolor Invention" means an Invention that is conceived or reduced
               ----------------
to practice by an employee or agent of Adolor solely or jointly with a Third
Party.

         1.5  "Adolor Know-How" means all present and future Know-How that
               ---------------
relates to the Collaboration Products, the Compound or the Adolor Inventions, to
the extent necessary for GSK to perform its obligations or enjoy its rights
under this Agreement, and which during the Term are in Adolor's or any of its
Affiliates' possession or control and are or become owned by, or otherwise may
be licensed by, Adolor. Adolor Know-How does not include any Adolor Patents.

         1.6  "Adolor Patents" means all Patent Rights covering the
               --------------
Collaboration Products, the Compound or the Adolor Inventions which are or
become owned by Adolor or Adolor's Affiliates, or as to which Adolor or Adolor's
Affiliates are or become licensed, now or in the future, with the right to grant
the sublicense rights granted to GSK under this Agreement, which Patent Rights
cover the making, having made, use, offer for sale, sale or importation of
Collaboration Products, and which existing Patent Rights are more specifically
set forth on Schedule 1.6.
             ------------

         1.7  "Adolor Product Marketing Contribution" means an amount equal to
               -------------------------------------
** for Adolor Products in the applicable reporting period in the United States
less the following amounts: (a) ** of the Adolor Product constituting such **;
(b) the **; (c) royalties paid to ** on account of sales of Adolor Products in
**; and (d) **.

         1.8  "Adolor Product Promotion Term" means the period of time beginning
               -----------------------------
on the Effective Date and ending ** years after First Commercial Sale of a POI
Product in the United States unless otherwise extended pursuant to the
provisions of Section 16.2.

         1.9  "Adolor Product Trademarks" shall have the meaning set forth in
               -------------------------
Section 2.4.1.

         1.10 "Adolor Products" means a POI Product, an OBD Acute Product or any
               ---------------
Additional Product designated by the Parties as an Adolor Product pursuant to
Section 4.3.

         1.11 "Adolor Reconciliation Report" shall have the meaning set forth in
               ----------------------------
Section 6.7.5(a).

         1.12 "Adolor Report" shall have the meaning set forth in Section 6.7.3.
               -------------

         1.13 "Adverse Drug Experience" means any of: an "adverse drug
               -----------------------
experience," a "life-threatening adverse drug experience," a "serious adverse
drug experience," or an "unexpected adverse drug experience," as those terms are
defined at either 21 C.F.R.(S)312.32 or 21 C.F.R.(S)314.80.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -2-

<PAGE>

         1.14  "Affiliate" of a Party means any Person, whether de jure or de
                ---------
facto, which directly or indirectly controls, is controlled by, or is under
common control with such Person for so long as such control exists, where
"control" means the decision-making authority as to such Person and, further,
where such control shall be presumed to exist where a Person owns more than
fifty percent (50%) of the equity (or such lesser percentage which is the
maximum allowed to be owned by a foreign corporation in a particular
jurisdiction) having the power to vote on or direct the affairs of the entity.

         1.15  "API Compound" means bulk quantities of Compound prior to the
                ------------
commencement of secondary manufacturing resulting in a Collaboration Product.

         1.16  "API Compound Carrying Cost" means ** percent (**%) of the
                --------------------------
dollar amount obtained by multiplying the average dollar value of API Compound
in a Calendar Quarter held in inventory by a Party for use in Development or
Commercialization of Collaboration Products by ** percent (**%).

         1.17  "Applicable Committee" shall have the meaning set forth in
                --------------------
Section 12.3.

         1.18  "Auditing Party" shall have the meaning set forth in Section
                --------------
6.14.


         1.19  "Breaching Party" shall have the meaning set forth in Section
                ---------------
16.3.


         1.20  "Business Day" means any day on which banking institutions in
                ------------
both New York, New York, United States and London, England are open for
business

         1.21  "Calendar Quarter" means for each Calendar Year, each of the
                ----------------
three month periods ending March 31, June 30, September 30 and December 31;
provided, however, that the first calendar quarter for the first Calendar Year
shall extend from the Effective Date to the end of the first complete calendar
quarter thereafter.

         1.22  "Calendar Year" means, for the first calendar year, the period
                -------------
commencing on the Effective Date and ending on December 31 of the calendar year
during which the Effective Date occurs, and each successive period beginning on
January 1 and ending twelve (12) consecutive calendar months later on December
31.

         1.23  "Call" means a personal visit by a Sales Representative to a
                ----
member of the Target Audience legally permitted to prescribe prescription drugs
in the United States during which such Sales Representative Details a
Collaboration Product. The Parties may, by mutual agreement, designate
additional types of Calls.

         1.24  "Claims" means all charges, complaints, actions, suits,
                ------
proceedings, hearings, investigations, claims and demands.

         1.25  "Collaboration Products" means the Adolor Products and the GI
                ----------------------
Products.

         1.26  "Combination Product" shall have the meaning set forth in Section
                -------------------
2.1.7.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -3-

<PAGE>


         1.27 "Commercialization" means any and all activities directed to
               -----------------
marketing, promoting, distributing, offering for sale and selling a
Collaboration Product, importing a Collaboration Product (to the extent
applicable) and conducting Phase IV Studies, including, without limitation and
where applicable, Co-Promoting. When used as a verb, "Commercialize" means to
                                                      -------------
engage in Commercialization.

         1.28 "Commercially Reasonable Efforts" means, with respect to a Party,
               -------------------------------
**.

         1.29 "Compound" means the peripheral mu antagonist having molecular
               --------
formula(+)-[[2(S)-[[4(R)-(3-hydroxyphenyl)-3(R),4-dimethyl-1-piperidinyl]-
methyl]-1-oxo-3-phenylpropyl]amino]acetic acid dihydrate, known generically as
"alvimopan", and all pharmaceutically acceptable salts and solvates thereof.

         1.30 "Confidential Information" means all secret, confidential or
               ------------------------
proprietary information or data, whether provided in written, oral, graphic,
video, computer or other form, provided by one Party (the "Disclosing Party") to
                                                           ----------------
the other Party (the "Receiving Party") pursuant to this Agreement or generated
                      ---------------
pursuant to this Agreement, including but not limited to, information relating
to the Disclosing Party's existing or proposed research, development efforts,
patent applications, business or products, the terms of this Agreement and any
other materials that have not been made available by the Disclosing Party to the
general public. Notwithstanding the foregoing sentence, Confidential Information
shall not include any information or materials that:

              1.30.1 were already known to the Receiving Party (other than under
an obligation of confidentiality), at the time of disclosure by the Disclosing
Party to the extent such Receiving Party has documentary evidence to that
effect;

              1.30.2 were generally available to the public or otherwise part of
the public domain at the time of its disclosure to the Receiving Party;

              1.30.3 became generally available to the public or otherwise part
of the public domain after its disclosure or development, as the case may be,
and other than through any act or omission of a Party in breach of such Party's
confidentiality obligations under this Agreement;

              1.30.4 were disclosed to a Party, other than under an obligation
of confidentiality, by a Third Party who had no obligation to the Disclosing
Party not to disclose such information to others; or

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -4-

<PAGE>

              1.30.5 were independently discovered or developed by or on behalf
of the Receiving Party without the use of the Confidential Information belonging
to the other Party and the Receiving Party has documentary evidence to that
effect.

         1.31 "Constipation Product" means a Product for the management of
               --------------------
non-opioid induced forms of constipation or bowel dysfunction which such Product
is not an IBS Product.

         1.32 "Co-Promotion" means those promotional activities undertaken by a
               ------------
pharmaceutical company's sales force in concert with at least one other
pharmaceutical company's sales force to implement the marketing plans and
strategies with respect to a particular prescription pharmaceutical product
under a single trademark. When used as a verb, "Co-Promote" shall mean to engage
                                                ----------
in such activities.

         1.33 "Cost of Goods" means the total cost of API Compound and/or a
               -------------
Collaboration Product (in formulated and/or finished packaged and labeled form)
as invoiced by Third Parties, including without limitation the sum of the
following actual costs: **. In the event that GSK manufactures API Compound
and/or Collaboration Products pursuant to Article 10, Cost of Goods shall be
calculated in accordance with Schedule 1.33.
                              -------------

         1.34 "Country" means any generally recognized sovereign entity.
               -------

         1.35 "CRO(s)" shall have the meaning set forth in Section 2.3.2(b).
               ------

         1.36 "Defaulting Party" shall have the meaning set forth in Section
               ----------------
6.3.4.

         1.37 "Designated Foreign Filing" shall have the meaning set forth in
               -------------------------
Section 15.1.2(b).

         1.38 "Detail" or "Detailing" means, with respect to a Collaboration
               ------      ---------

Product, the communication by a Sales Representative during a Call to a member
of the Target Audience (a) involving face-to-face contact, (b) describing in a
fair and balanced manner the FDA-approved indicated uses and other relevant
characteristics of such Collaboration Product, (c) using the Promotional
Materials in an effort to increase the Target Audience prescribing and/or
hospital ordering preferences of a Collaboration Product for its FDA-approved
indicated uses, and (d) made at the Target Audience member's office, in a
hospital, at marketing meetings sponsored by a Party for the Collaboration
Products or other appropriate venues conducive to pharmaceutical product
informational communication where the principal objective is to place an
emphasis, either primary or secondary, on a Collaboration Product and not simply
to discuss a Collaboration Product with a member of the Target Audience. For the
avoidance of doubt, discussions at conventions shall not constitute "Details" or
"Detailing".

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -5-

<PAGE>

     1.39 "Detail Cost" means, unless otherwise agreed to by the Parties, **
           -----------
dollars ($**) for each Major Detail, ** dollars ($**) for each Secondary Detail
and ** dollars ($**) if such Detail was conducted by a Specialist Sales
Representative, in each case adjusted for inflation beginning with respect to
Calendar Year beginning January 1, 2003, using the Producer Price Index as
published by the Bureau of Labor Statistics of the U.S. Department of Labor.

     1.40 "Detail Requirements" shall have the meaning set forth in Section 5.7.
           -------------------

     1.41 "Development" or "Develop" means preclinical and clinical drug
           -----------      -------
development activities, including, among other things: test method development
and stability testing, toxicology, formulation, process development,
manufacturing scale-up, development-stage manufacturing, current Good
Manufacturing Practices audits, current Good Clinical Practices audits, current
Good Laboratory Practices audits, analytical method validation, manufacturing
process validation, cleaning validation, scale-up and post approval changes,
quality assurance/quality control development, statistical analysis and report
writing, preclinical and clinical studies, including, without limitation, Phase
I Studies, Phase II Studies, Phase III Studies, regulatory filing submission and
approval, and regulatory affairs related to the foregoing. When used as a verb,
"Develop" means to engage in Development. For clarity, Development does not
 -------
include Phase IV Studies.

     1.42 "Development Expenses" means, for all studies or activities performed
           --------------------
by or on behalf of either Party or any of its Affiliates to the extent provided
for in an approved U.S. Development Plan or otherwise approved in advance by the
Joint Development Committee or Joint Steering Committee, including without
limitation Phase III Studies, that are relevant to the Development of
Collaboration Products for Commercialization in the United States:

          1.42.1 ** costs and expenses incurred (i.e., paid or accrued) to a **,
in connection with all Development activities performed in accordance with the
U.S. Development Plan;

          1.42.2 the cost of clinical supplies for such studies or activities as
agreed in the U.S. Development Plan, which costs shall be comprised of (i) the
cost of clinical and pre-clinical supplies, including Compound, utilized in
Development, (ii) out-of-pocket costs and expenses incurred in purchasing
comparator drug and in packaging comparator drug and/or the Collaboration
Products, shipping clinical supplies to centers or disposal of clinical
supplies, and (iii) actual costs of packaging comparator if done by a Party.

     It is understood and agreed that development expenses relating to the
     Collaboration Products in the United States incurred by Adolor after ** and
     prior to the formation of the Joint Development Committee and the Joint
     Steering Committee shall be included as Development Expenses.

     1.43 "Development Milestone" shall have the meaning set forth in Section
           ---------------------
6.2.1.

     1.44 "Disclosing Party" shall have the meaning set forth in Section 1.30.
           ----------------

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -6-

<PAGE>

     1.45 "Dispute Detailing Audit Data" means the absolute number of Details
           ----------------------------
performed by a Party's Sales Representatives for a given Calendar Year, as
reflected in the Personal Selling Audit and Hospital Personal Selling Audit of
Scott-Levin Associates or IMS America. In the event the Personal Selling Audit
or Hospital Personal Selling Audit for any given period or periods does not
report details for the physician specialties which correspond to the Target
Audience, the Parties shall mutually agree upon an alternative methodology to
verify the internal Detailing records of a Party.

     1.46 "Distribution Services Fee" shall have the meaning set forth in
           -------------------------
Section 6.3.3.

     1.47 "Exchange Act" shall have the meaning set forth in Section 17.1.1.
           ------------

     1.48 "FDA" means the United States Food and Drug Administration and any
           ---
successor agency thereto.

     1.49 "Field" means all uses of Compound in human beings except in products
           -----
or formulations containing Compound and opioids.

     1.50 "First Commercial Sale" means the first shipment of commercial
           ---------------------
quantities of any Collaboration Product sold to a Third Party by a Party or its
sublicensees in any Country after receipt of Marketing Authorization Approval
for such Collaboration Product in such Country. Sales for test marketing,
sampling and promotional uses, clinical trial purposes or compassionate or
similar uses shall not be considered to constitute a First Commercial Sale.

     1.51 "Force Majeure Event" shall have the meaning set forth in Section
           -------------------
18.3.

     1.52 "Generic Competition" means, on a Country-by-Country basis and
           -------------------
Collaboration Product-by-Collaboration Product basis, the presence of a drug
product that contains the same active ingredient as the Collaboration Product
(inactive ingredients may vary), is identical to the Collaboration Product in
strength, dosage form and route of administration, is bioequivalent to the
Collaboration Product and is approved by the relevant Governmental Authority in
such Country and which has obtained sales greater than ** (**%) of the combined
sales of such Collaboration Product together with such generic drug products,
**, in any Calendar Quarter, and which generic drug product sales are evidenced
by independent market data (where available), such as that published by IMS.

     1.53 "GI Product" means an OBD Chronic Product, a Constipation Product, an
           ----------
IBS Product, or any Additional Product designated by the Parties as a GI Product
pursuant to Section 4.3.

     1.54 "GI Product Marketing Contribution" means an amount equal to Net Sales
           ---------------------------------
for GI Products in the applicable reporting period in the United States less the
following amounts: (a) ** of the GI Product constituting such **; (b) the **;
(c) royalties paid to ** on account of sales of ** Products in the United
States; (d) **; and (e) ** for such ** Product.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -7-

<PAGE>

     1.55 "GI Product Promotion Term" means, on a GI Product-by-GI Product
           -------------------------
basis, the period from the Effective Date until the later of (a) the expiration
or termination of the last Valid Claim of a Patent Right covering such GI
Product in the United States, (b) ** (**) years from First Commercial Sale in
the United States, and (c) the existence of Generic Competition for two (2)
consecutive Calendar Quarters for such GI Product in the United States.

     1.56 "GI Product Trademarks" shall have the meaning set forth in Section
           ---------------------
2.4.2.

     1.57 "Governmental Authority" means any court, tribunal, arbitrator,
           ----------------------
agency, legislative body, commission, official or other instrumentality of (i)
any government of any Country, (ii) a federal, state, province, county, city or
other political subdivision thereof or (iii) any supranational body, including
without limitation the European Agency for the Evaluation of Medicinal Products.

     1.58 "GSK Housemark" means the name and logo of GSK or an Affiliate of GSK
           -------------
as identified by GSK to Adolor from time to time.

     1.59 "GSK Invention" means an Invention that is conceived or reduced to
           -------------
practice by an employee or agent of GSK solely or jointly with a Third Party.

     1.60 "GSK Know-How" means all present and future Know-How that relates to
           ------------
the Collaboration Products, the Compound or the GSK Inventions, to the extent
necessary for Adolor to perform its obligations or enjoy its rights under this
Agreement, and which during the Term are in GSK's or any of its Affiliates'
possession or control and are or become owned by, or otherwise may be licensed
by, GSK. GSK Know-How does not include any GSK Patents.

     1.61 "GSK Other GI Product" shall have the meaning set forth in Section
           --------------------
4.3.3(b).

     1.62 "GSK Patent" means all Patent Rights covering the Collaboration
           ----------
Products, the Compound or the GSK Inventions which are or become owned by GSK or
GSK's Affiliates, or as to which GSK or GSK's Affiliates otherwise are or become
licensed, now or in the future, with the right to grant the sublicense rights
granted to Adolor under this Agreement, which Patent Rights cover the making,
having made, use, offer for sale, sale or importation of the Collaboration
Products or the Compound.

     1.63 "GSK Product" shall have the meaning set forth in Section 11.1.
           -----------

     1.64 "GSK Product Agreement" shall have the meaning set forth in Section
           ---------------------
11.2.2.

     1.65 "GSK Product Selection Period" shall have the meaning set forth in
           ----------------------------
Section 11.2.3.

     1.66 "GSK Reconciliation Report" shall have the meaning set forth in
           -------------------------
Section 6.7.5(b).

     1.67 "GSK Report" shall have the meaning set forth in Section 6.7.2.
           ----------

     1.68 "Hatch-Waxman Certification" shall have the meaning set forth in
           --------------------------
Section 15.3.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -8-

<PAGE>

     1.69 "Hostile Tender Offer" shall have the meaning set forth in Section
           --------------------
17.2.5.

     1.70 "HSR Act" shall have the meaning set forth in Section 13.2.6.
           -------

     1.71 "IBS Product" means a Product for the management of irritable bowel
           -----------
syndrome which such Product is not a Constipation Product.

     1.72 "Indemnified Party" shall have the meaning set forth in Section
           -----------------
14.3.1.

     1.73 "Indemnifying Party" shall have the meaning set forth in Section
           ------------------
14.3.1.

     1.74 "Initial Incentive Period" shall have the meaning set forth in Section
           ------------------------
5.8.

     1.75 "Initial Three Year Period" shall have the meaning set forth in
           -------------------------
Section 6.3.1.

     1.76 "Internal Detailing Report" shall have the meaning set forth in
           -------------------------
Section 5.9.1.

     1.77 "Invention" means any discovery (whether patentable or not) conceived
           ---------
or reduced to practice during the Term as a result of the Development or
Commercialization activities and related to, derived from or useful for the
manufacture, use or sale of the Compound or a Collaboration Product.

     1.78 "Investigational Authorization" means, with respect to a Country, the
           -----------------------------
regulatory authorization required to investigate a Collaboration Product in such
Country as granted by the relevant Governmental Authority.

     1.79 "Joint Development Committee" shall have the meaning set forth in
           ---------------------------
Section 3.2.1.

     1.80 "Joint Invention" means an Invention that is conceived or reduced to
           ---------------
practice jointly by employees and/or agents of both Adolor and GSK.

     1.81 "Joint Marketing Committee" shall have the meaning set forth in
           -------------------------
Section 3.3.1.

     1.82 "Joint Supply Committee" shall have the meaning set forth in Section
           ----------------------
3.4.1.

     1.83 "Joint Steering Committee" shall have the meaning set forth in Section
           ------------------------
3.1.1.

     1.84 "Know-How" means any technical information, know-how and materials,
           --------
including without limitation all biological, chemical, pharmacological,
toxicological, clinical, assay and other information, data, discoveries,
inventions, improvements, processes, formulae and trade secrets, patentable or
otherwise.

     1.85 "Laws" means all laws, statutes, rules, regulations (including,
           ----
without limitation, current Good Manufacturing Practice Regulations as specified
in 21 C.F.R. (S)(S) 210 and 211; Investigational New Drug Application
regulations at 21 C.F.R. (S) 312; NDA regulations at 21 C.F.R. (S) 314, relevant
provisions of the Federal Food, Drug and Cosmetic Act, and other laws and
regulations enforced by the FDA), ordinances and other pronouncements having the
binding effect of law of any Governmental Authority.

                                       -9-

<PAGE>

     1.86 "Lilly" means Eli Lilly and Company and its successors and permitted
           -----
assigns.

     1.87 "Litigation Condition" shall have the meaning set forth in Section
           --------------------
14.3.2.

     1.88 "Losses" means any and all damages (including all incidental,
           ------
consequential, statutory and treble damages), awards, deficiencies, settlement
amounts, defaults, assessments, fines, dues, penalties, costs, fees,
liabilities, obligations, taxes, liens, losses, lost profits and expenses
(including without limitation court costs, interest and reasonable fees of
attorneys, accountants and other experts) incurred by or awarded to Third
Parties and required to be paid to Third Parties with respect to a Claim by
reason of any judgment, order, decree, stipulation or injunction, or any
settlement entered into in accordance with the provisions of this Agreement,
together with all documented out-of-pocket costs and expenses incurred in
complying with any judgments, orders, decrees, stipulations and injunctions that
arise from or relate to a Claim of a Third Party.

     1.89 "Major Detail" means a Detail for a Collaboration Product in which
           ------------
such Collaboration Product receives the predominant portion of emphasis and time
during the Call (i.e., no other product receives more emphasis or time during
the Call).

     1.90 "Major Market Country" means each of Australia, Japan, Canada and all
           --------------------
members states of the European Union as of the Effective Date (other than
Luxemborg and Greece).

     1.91 "Major Region" means the Country or Countries in each of the following
           ------------
geographic regions: (a) Europe; (b) Canada; (c) Middle East and Africa; (d)
Japan; (e) Asia-Pacific; and (f) Mexico, Central America and South America.

     1.92 "Marketing Authorization" means, with respect to a Country, the
           -----------------------
regulatory authorization required to market and sell a Collaboration Product in
such Country as granted by the relevant Governmental Authority.

     1.93 "Marketing Authorization Approval" shall mean approval by a
           --------------------------------
Governmental Authority for sale of a Collaboration Product, including any
applicable pricing, final labeling or reimbursement approvals.

     1.94 "Marketing Expenses" means, excluding any Development Expenses, all
           ------------------
** costs and expenses incurred (i.e., paid or accrued) to a **, whether
                                ---
incurred by Adolor or its Affiliates, or GSK or its Affiliates, to the extent
provided for in an approved U.S. Marketing Plan or otherwise approved in advance
by the Joint Marketing Committee or the Joint Steering Committee, and solely to
the extent related to Collaboration Products, for Commercialization in the
United States in connection with:

          1.94.1 Marketing, advertising, sampling and promoting a Collaboration
Product, including without limitation educational expenses, speakers' programs
and symposia, and joint marketing and sales meetings in accordance with Section
5.10.4, but excluding ** unless otherwise mutually agreed by the Parties;

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                       -10-

<PAGE>

         1.94.2 **;

         1.94.3 Primary and secondary market research;

         1.94.4 Promotional Materials; and

         1.94.5 Samples (at Cost of Goods) distributed in the United States.

         It is understood and agreed that marketing expenses relating to the
         Collaboration Products in the United States incurred by Adolor after
         ** and prior to the formation of the Joint Marketing Committee and the
         Joint Steering Committee shall be included as Marketing Expenses but
         Marketing Expenses shall not include any: (a) costs associated with
         distribution of Collaboration Products to be provided by GSK pursuant
         to Section 5.5.2(b); or (b) costs or expenses incurred by a Party for
         services that are performed by a Third Party if such services are of a
         type that are normally performed by ** unless the Joint Marketing
         Committee has designated such services be performed by external
         personnel consistent with quality and timeliness objectives. It is
         further understood and agreed that Marketing Expenses shall not
         include the costs or expenses incurred by a Party for performance of
         its Detailing obligations under Article 5.

         1.95 "NDA" means a new drug application or supplemental new drug
               ---
application or any amendments thereto submitted to the FDA in the United States.

         1.96 "NDA Acceptance" shall mean the written notification by the FDA
               --------------
that the NDA has met all the criteria for filing acceptance pursuant to 21
C.F.R.(S)314.101.

         1.97 "Net Sales" for each Country means the aggregate gross amount
               ---------
invoiced on account of sales if a Collaboration Product by a Party or any of its
Affiliates or their sublicensees to a Third Party in the relevant Country (but
not including sales between a Party and its Affiliates where such Collaboration
Product is intended for resale) less the following relating to such sales:**

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -11-

<PAGE>

         **

         1.98  "Net Sales Report" shall have the meaning set forth in Section
                ----------------
6.6.2.

         1.99  "OBD Acute Product" means a Product for the management of opioid
                -----------------
induced bowel dysfunction in hospitalized patients or patients discharged from a
hospital for whom prescriptions or **.

         1.100 "OBD Chronic Product" means a Product for the management of
                -------------------
patients with bowel dysfunction caused by the ** administration of opioids.

         1.101 "Officers" shall have the meaning set forth in Section 3.1.4(b).
                --------

         1.102 "OTC" means the over-the-counter, non-prescription market as
                ---
opposed to prescription sales.

         1.103 "Patent Infringement Claim" shall have the meaning set forth in
                -------------------------
Section 15.2.1.

         1.104 "Patent Infringement Notice" shall have the meaning set forth in
                --------------------------
Section 15.2.2.

         1.105 "Patent Rights" means all existing patents and patent
                -------------
applications and all patent applications hereafter filed, including any
continuations, continuations-in-part, divisions, provisionals or any substitute
applications, any patent issued with respect to any such patent applications,
any reissue, reexamination, renewal or extension (including any supplementary
protection certificate) of any such patent, and any confirmation patent or
registration patent or patent of addition based on any such patent, and all
foreign counterparts of any of the foregoing, or as applicable portions thereof
or individual claims therein.

         1.106 "PDM Act" shall have the meaning set forth in Section 7.2.3.
                -------

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -12-

<PAGE>

         1.107 "Person" means any natural person, corporation, general
                ------
partnership, limited partnership, joint venture, proprietorship or other
business organization.

         1.108 "Pharmacovigilance Agreement" means the Pharmacovigilance and
                ---------------------------
Global Safety Reporting Agreement to be entered into by the Parties pursuant to
Section 9.6.

         1.109 "Phase I Studies" means that portion of the U.S. Development
                ---------------
Plan, ROW Development Plan or Development relating to each Collaboration Product
which provides for the first introduction into humans of such Collaboration
Product including small scale clinical studies conducted in normal volunteers or
patients to obtain information on such Collaboration Product's safety,
tolerability, pharmacological activity, pharmacokinetics, drug metabolism and
mechanism of action, as well as early evidence of effectiveness, as more fully
defined in 21 C.F.R. (S) 312.21(a).

         1.110 "Phase II Studies" means that portion of the clinical U.S.
                ----------------
Development Plan, ROW Development Plan or Development relating to each
Collaboration Product which provides for well controlled clinical trials of such
Collaboration Product in patients, including clinical studies conducted in
patients with the condition, and designed to evaluate clinical efficacy and
safety for such Collaboration Product for one or more indications, as well as to
obtain an indication of the dosage regimen required, as more fully defined in 21
C.F.R. (S) 312.21(b).

         1.111 "Phase III Studies" means that portion of the clinical U.S.
                -----------------
Development Plan, ROW Development Plan or Development relating to each
Collaboration Product which provides for large scale, pivotal, clinical studies
conducted in a sufficient number of patients and whose primary objective is to
obtain a definitive evaluation of the therapeutic efficacy and safety of the
Collaboration Product in patients for the particular indication in question that
is needed to evaluate the overall risk-benefit relationship of Collaboration
Product and to provide adequate basis for obtaining requisite regulatory
approval(s) and product labeling, as more fully defined in 21 C.F.R. (S)
312.21(c).

         1.112 "Phase IV Studies" means a study for a Collaboration Product that
                ----------------
is initiated in a Country after receipt of a Marketing Authorization for a
Collaboration Product in the United States and which is expected to be completed
with respect to an Adolor Product during the Adolor Product Promotion Term and
with respect to a GI Product during the GI Product Promotion Term and is
principally intended to support the marketing and Commercialization of such
Collaboration Product in the United States, including without limitation
investigator initiated trials, clinical experience trials and studies conducted
to fulfill local commitments made as a condition of any Marketing Authorization.

         1.113 "POI Contract Product Profile" means the contract product profile
                ----------------------------
for the POI Product attached hereto as Schedule 1.113.
                                       --------------

         1.114 "POI Product" means a Product for the prevention, treatment or
                -----------
management of post-operative ileus or post-operative bowel dysfunction.

         1.115 "PONV Product" means a Product for the management of
                ------------
post-operative nausea or vomiting.

                                      -13-

<PAGE>

         1.116 "Product" means a prescription pharmaceutical product that
                -------
contains Compound as the sole active ingredient for use in the Field. For the
avoidance of doubt, Product shall not include products sold in the OTC market.

         1.117 "Product Liability Claim" shall have the meaning set forth in
                -----------------------
Section 14.5.1.

         1.118 "Product Supplier" means any manufacturer, packager or processor
                ----------------
of Compound or a Collaboration Product for development, promotion and sale.

         1.119 "Promotional Materials" means all written, printed, video or
                ---------------------
graphic advertising, promotional, educational and communication materials (other
than Collaboration Product labeling) for marketing, advertising and promotion of
the Collaboration Products for use in the United States by (a) a Sales
Representative or (b) advertisements or direct mail pieces, in accordance with
the terms of the applicable U.S. Marketing Plan.

         1.120 "Receiving Party" shall have the meaning set forth in Section
                ---------------
1.30.

         1.121 "Recording Party" shall have the meaning set forth in Section
                ---------------
6.14.

         1.122 "ROW" means Countries other than the United States.
                ---

         1.123 "ROW Development Plan" shall have the meaning set forth in
                --------------------
Section 4.7.2.

         1.124 "ROW Net Sales Forecast" shall have the meaning set forth in
                ----------------------
Section 5.11.2(c).

         1.125 "ROW Term" means, on a Country-by-Country and Collaboration
                --------
Product-by-Collaboration Product basis, the period from the Effective Date until
the later of (a) the expiration or termination of the last Valid Claim of a
Patent Right covering such Collaboration Product in such Country, (b) ** (**)
years from First Commercial Sale in such Country, and (c) the existence of
Generic Competition for two (2) consecutive Calendar Quarters for such
Collaboration Product in such Country.

         1.126 "ROW Trademarks" shall have the meaning set forth in Section
                --------------
2.4.3.

         1.127 "Royalty Conversion Election" shall have the meaning set forth in
                ---------------------------
Section 6.3.5.

         1.128 "Sales Representative" means a professional pharmaceutical sales
                --------------------
representative engaged or employed by either Party to conduct, among other sales
responsibilities, Detailing and other promotional efforts with respect to the
Collaboration Products and who has been trained by either Party in accordance
with a training protocol to be agreed upon by the Parties.

         1.129 "Samples" means Collaboration Product packaged and distributed to
                -------
members of the Target Audience as a complementary trial for use with patients in
the United States and in accordance with the PDM Act.

         1.130 "SEC" shall have the meaning set forth in Section 17.1.2.
                ---

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -14-

<PAGE>

         1.131 "Secondary Detail" means a Detail for a Collaboration Product in
                ----------------
which such Collaboration Product receives the second most emphasis and time
during the Call (i.e., at most, only one other product receives greater emphasis
and time during the Call).

         1.132 "Selected GSK Product" shall have the meaning set forth in
                --------------------
Section 11.2.2.

         1.133 "Shire" means Shire Pharmaceuticals Group plc and its successors
                -----
and permitted assigns.

         1.134 "Specialist Sales Representative" means a Sales Representative
                -------------------------------
who has specialist skills and/or knowledge in relation to the practice areas of
some or all of those physician groups which make up the Target Audience and who,
as a result of such skills and/or knowledge, has as one of his or her principal
functions the promotion of pharmaceutical products to such physician groups.

         1.135 "Standard Terms" shall have the meaning set forth in Section
                --------------
10.6.4.

         1.136 "Target Audience" means (a) for the POI Product, the physician
                ---------------
specialties set forth on Schedule 1.136 with authority to prescribe a
                         --------------
pharmaceutical product or issue hospital orders for a pharmaceutical product in
the United States, and (b) for each other Collaboration Product, the physician
specialties identified in the U.S. Marketing Plan for such Collaboration
Product, in each case as may be amended from time to time by the Joint Marketing
Committee.

         1.137 "Taxes" shall have the meaning set forth in Section 6.13.
                -----

         1.138 "Term" means the longer of the United States Term and the ROW
                ----
Term.

         1.139 "Terminated Collaboration Product" shall have the meaning set
                --------------------------------
forth in Section 16.12.

         1.140 "Testing Protocol" shall have the meaning set forth in Section
                ----------------
3.4.2(a).

         1.141 "Third Party" means a Person who is not a Party or an Affiliate
                -----------
of a Party.

         1.142 "Third Party Claim" shall have the meaning set forth in Section
                -----------------
14.3.1.

         1.143 "Trademark Infringement Claim" shall have the meaning set forth
                ----------------------------
in Section 2.4.8(a).

         1.144 "Trademark Infringement Notice" shall have the meaning set forth
                -----------------------------
in Section 2.4.8(b).

         1.145 "United States" means the United States, its territories and
                -------------
possessions.

         1.146 "U.S. Development Plan" means the plan for each Collaboration
                ---------------------
Product designed to achieve the Development for such Collaboration Product for
the United States, including, without limitation, the budget and nature, number
and schedule of Development activities. The initial U.S. Development Plans for
the POI Product and the OBD Chronic Product are attached hereto as Schedule
                                                                   --------
1.146, and as they may be amended in accordance with the terms of this
-----
Agreement.

                                      -15-

<PAGE>

         1.147 "U.S. Marketing Plan" means for each Collaboration Product a plan
                -------------------
and budget for the promotion and marketing of the Collaboration Products in the
United States as developed and approved under Section 5.1.

         1.148 "United States Term" means the longer of the Adolor Product
                ------------------
Promotion Term and the GI Product Promotion Term.

         1.149 "Valid Claim" means any claim of a pending patent application
                -----------
which has not been abandoned or finally rejected without the right of appeal or
which is not knowingly patentable, or any claim from an issued and unexpired
patent included within the Patent Rights which has not been revoked or held
unenforceable or invalid by a decision of a court or other Governmental
Authority of competent jurisdiction, and which has not been disclaimed, denied
or admitted to be invalid or unenforceable through reissue or disclaimer or
otherwise.

         1.150 "Withholding Party" shall have the meaning set forth in Section
                -----------------
6.13.

                                   ARTICLE 2
                             RIGHTS AND OBLIGATIONS

         2.1   License Grants from Adolor to GSK.
               ---------------------------------

               2.1.1 United States Development License. Subject to the terms of
                     ---------------------------------
this Agreement, Adolor grants to GSK, and GSK accepts, an exclusive (except as
to Adolor and its Affiliates) and non-transferable (except in accordance with
Section 2.3) license under the Adolor Patents, Adolor Know-How and Adolor's
rights in the Joint Inventions (a) during the Adolor Product Promotion Term, to
use and Develop Adolor Products for Commercialization in the United States, and
(b) during the GI Product Promotion Term, to make, have made (subject to Section
2.3), use and Develop GI Products for Commercialization in the United States. In
the event the Parties agree pursuant to Article 10 that GSK will manufacture
Adolor Products for sale in the United States, the license grant in Section
2.1.1(a) shall also include rights to make and have made (subject to Section
2.3) Adolor Products in the United States.

               2.1.2 ROW Development License. Subject to the terms of this
                     -----------------------
Agreement,during the ROW Term, Adolor grants to GSK, and GSK accepts, an
exclusive and non-transferable (except in accordance with Section 2.3) license
under the Adolor Patents, Adolor Know-How and Adolor's rights in the Joint
Inventions to make, have made (subject to Section 2.3), use and Develop
Collaboration Products for Commercialization in the ROW.

               2.1.3 United States Co-Promotion Rights. Subject to the terms of
                     ---------------------------------
this Agreement, Adolor grants to GSK, and GSK accepts, an exclusive (except as
to Adolor and its Affiliates) and non-transferable (except in accordance with
Section 2.3) right under the Adolor Patents, Adolor Know-How and Adolor's rights
in the Joint Inventions to Co-Promote (a) during the Adolor Product Promotion
Term, Adolor Products with Adolor in the United States, and (b) during the GI
Product

                                      -16-

<PAGE>

Promotion Term, OBD Chronic Product, and other GI Products where Adolor has
elected to fund Development under Section 4.6.5 and where Adolor has not made a
Royalty Conversion Election, with Adolor in the United States.

               2.1.4 Commercialization License in United States. Subject to the
                     ------------------------------------------
terms of this Agreement, and in addition to the Co-Promotion rights granted
under Section 2.1.3, during the GI Product Promotion Term, Adolor hereby grants
to GSK, and GSK accepts, an exclusive (except as to Adolor and its Affiliates)
and non-transferable (except in accordance with Section 2.3) license under the
Adolor Patents, Adolor Know-How and Adolor's rights in the Joint Inventions to
make, have made (subject to Section 2.3), use, sell, offer for sale and import
GI Products in the United States.

             2.1.5 Commercialization License in ROW. Subject to the terms of
                   --------------------------------
this Agreement, during the ROW Term, Adolor hereby grants to GSK, and GSK
accepts, an exclusive and non-transferable (except in accordance with Section
2.3) license under the Adolor Patents, Adolor Know-How and Adolor's rights in
the Joint Inventions to make, have made (subject to Section 2.3), use, sell,
offer for sale and import Collaboration Products in the ROW.

             2.1.6 Manufacturing License in the Event of a Shortage. In the
                   ------------------------------------------------
event that GSK assumes manufacturing responsibility in accordance with Section
10.9, Adolor, subject to the terms of this Agreement, grants to GSK a
non-exclusive and non-transferable (except in accordance with Section 2.3)
license under the Adolor Patents, Adolor Know-How and Adolor's rights in the
Joint Inventions to make and have made API Compound or formulated Collaboration
Product.

             2.1.7 Combination Products. Subject to the terms of this Agreement,
                   --------------------
Adolor retains the exclusive right to develop, make, use, import, distribute,
sell, offer for sale and have sold products containing both Compound and an
opioid (each, a "Combination Product"). For purposes of clarification, a
                 -------------------
Combination Product shall not be deemed an Additional Product.

         2.2 License Grant from GSK to Adolor. Subject to the terms of this
             --------------------------------
Agreement, GSK grants to Adolor, and Adolor accepts, an exclusive (except as to
GSK and its Affiliates), irrevocable, non-transferable (except in accordance
with Section 2.3) ** license under the GSK Patents, GSK Know-How and GSK's
rights in the Joint Inventions (a) at all times during ** the Adolor Product
Promotion Term, to make, have made, use, sell, have sold, offer for sale and
import Adolor Products in the United States, (b) during the GI Product Promotion
Term, for the OBD Chronic Product and, where Adolor has elected to fund
Development of another GI Product under Section 4.6.5 and in each case where
Adolor has not made a Royalty Conversion Election, to Co-Promote the OBD Chronic
Product and such other GI Products in the United States, (c) **, to make, have
made, use, sell, have sold, offer for sale and import GI Products in the United
States, (d) **, to make, have made, use, sell, have sold, offer for sale

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -17-

<PAGE>

and import such Collaboration Product in such Country in the ROW, and (e)**, to
make, have made, use, sell, offer for sale, have sold and import, Combination
Products and Compound in all Countries of the world.

         2.3 Sublicensing and Subcontracting. Subject to this Section 2.3,
             -------------------------------
neither Party may sublicense or subcontract its rights under this Agreement to
an Affiliate or a Third Party without the prior written consent of the other
Party.

             2.3.1 GSK Sublicensing or Subcontracting to Affiliates. GSK may
                   ------------------------------------------------
sublicense or subcontract its rights to Develop or Commercialize in whole or in
part to one or more of its Affiliates, provided that the rights sublicensed or
subcontracted to such Affiliate shall automatically terminate upon a change of
control of such Affiliate in connection with which such Affiliate ceases to be
an Affiliate of GSK.

             2.3.2 GSK Sublicensing or Subcontracting to Third Parties.
                   ---------------------------------------------------

               (a) With respect to the Major Market Countries, GSK shall be
prohibited from sublicensing or subcontracting to any Third Party any of GSK's
rights to Commercialize the Collaboration Products without the prior written
consent of Adolor, such consent not to be unreasonably withheld or delayed. With
respect to all Countries of the ROW other than the Major Market Countries, GSK
shall be entitled to sublicense or subcontract to any Third Party any of GSK's
rights to Commercialize the Collaboration Products on a Country-by-Country basis
to the extent and only to the extent where such activity is in accordance with
GSK's usual business practices as applied in such Country.

               (b) If set forth in an agreed upon U.S. Development Plan or U.S.
Marketing Plan, or in GSK's discretion with respect to the ROW, GSK shall be
permitted to subcontract its Development activities or Phase IV Studies to one
or more Third Party contract research organizations ("CRO(s)"), or equivalent
                                                      ---
Third Party entities, to carry out certain Development activities on behalf of
GSK in relation to any Collaboration Product under this Agreement and, for the
avoidance of doubt, such CRO or equivalent Third Party entities shall not be
considered a sublicensee for the purposes of this Section 2.3.

         2.3.3 Adolor Sublicensing or Subcontracting to Affiliates. Adolor may
               ---------------------------------------------------
sublicense or subcontract its responsibilities to be performed under this
Agreement in whole or in part to one or more of its Affiliates, provided that
the rights sublicensed or subcontracted to such Affiliate shall automatically
terminate upon a change of control of such Affiliate in connection with which
such Affiliate ceases to be an Affiliate of Adolor.

         2.3.4 Adolor Sublicensing or Subcontracting to Third Parties. If set
               ------------------------------------------------------
forth in the applicable U.S. Development Plan or U.S. Marketing Plan, Adolor may
sublicense or subcontract its Development or Commercialization activities (other

                                      -18-

<PAGE>

than Detailing except as provided in this Section 2.3.4) to a Third Party. The
Parties agree that Adolor may request that GSK provide Sales Representatives to
perform Adolor's Details of Collaboration Products. In the event that GSK
provides such Sales Representatives, the related costs of and/or remuneration
for such Details so performed by GSK shall be agreed in good faith by the
Parties at such time, taking into account both the prevailing Detail Cost and
the cost of Details that could be provided by a Third Party contract sales
organization (whose primary business is to detail pharmaceutical products on
behalf of another party) for comparable number of Details and Sales
Representatives; provided that if GSK performs such Details, Adolor shall not be
considered a Defaulting Party and there shall be no adjustment pursuant to
Section 6.3.4. In the event that GSK does not provide such Sales
Representatives, Adolor may engage a contract sales organization (whose primary
business is to detail pharmaceutical products on behalf of another party) to
perform such Details. In addition, it is understood that Adolor may utilize a
contract sales organization (whose primary business is to detail pharmaceutical
products on behalf of another party) to recruit Sales Representatives for
Adolor.

         2.3.5 Liability for Affiliates, Sublicensees and Subcontractors. Each
               ---------------------------------------------------------
Party shall ensure that each of its Affiliates and permitted sublicensees or
subcontractors accepts and complies with all of the terms and conditions of this
Agreement as if such Affiliates or permitted sublicensees or subcontractors were
a party to this Agreement and each Party shall guarantee its Affiliates' and
permitted sublicensees' or subcontractors' performance under this Agreement.

         2.4 Trademarks and Housemarks.
             -------------------------


             2.4.1 United States Trademarks for Adolor Products; Adolor Trade
                   ----------------------------------------------------------
Dress. The Adolor Products shall be Commercialized in the United States under
-----
trademarks and trade dress selected by the Joint Marketing Committee and
approved by the Joint Steering Committee (the "Adolor Product Trademarks"). It
                                               -------------------------
is understood that Adolor has submitted to the FDA for consideration the
trademarks "Entereg" and "Alvanop" for possible use with the POI Product. If the
Joint Marketing Committee or the Joint Steering Committee selects a GI Product
Trademark for use in connection with an Adolor Product in the United States, GSK
shall license such GI Product Trademark for use by Adolor in connection with the
Commercialization of such Adolor Product in the United States, in which case
such GI Product Trademark will remain a GI Product Trademark and will not be
deemed an Adolor Product Trademark. The Adolor Product Trademarks shall be owned
by Adolor and GSK agrees to assign any rights it may have in the Adolor Product
Trademarks to Adolor. GSK shall have no rights under this Agreement in or to the
Adolor Product Trademarks or the goodwill pertaining thereto except as
specifically provided herein. GSK and its Affiliates shall utilize the Adolor
Product Trademarks only for the purposes contemplated herein. GSK agrees that
upon termination or expiration of the Adolor Product Promotion Term, it will
discontinue forthwith all use of the Adolor Product Trademarks except for
permitted use in the United States with a GI Product in the United States as set

                                      -19-

<PAGE>

forth in the license grant at Section 2.4.2 or with a Collaboration Product in
the ROW under its assigned rights in the ROW as set forth in Section 2.4.3.
Subject to Sections 16.10.2 and 16.11.2, to the extent Adolor licenses any of
its intellectual property to GSK under this Agreement for trade dress purposes
GSK acknowledges that nothing in this Agreement shall give it any right, title
or interest in such intellectual property.

             2.4.2 United States Trademarks for GI Products; GSK Trade Dress.
                   ---------------------------------------------------------
 The GI Products shall be Commercialized in the United States under trademarks
and trade dress selected by the Joint Marketing Committee and approved by the
Joint Steering Committee (the "GI Product Trademarks"). If an Adolor Product
                               ---------------------
Trademark is so selected for use with a GI Product in the United States, Adolor
shall license such Adolor Product Trademark for use by GSK in connection with
the Commercialization of such GI Product in the United States, in which case
such Adolor Product Trademark will remain an Adolor Product Trademark and will
not be deemed a GI Product Trademark. The GI Product Trademarks shall be owned
by GSK and Adolor agrees to assign any rights it may have in the GI Product
Trademarks to GSK. Adolor shall have no rights under this Agreement in or to the
GI Product Trademarks or the goodwill pertaining thereto except as specifically
provided herein. Adolor and its Affiliates shall utilize the GI Product
Trademarks only for the purposes contemplated herein. Adolor agrees that upon
termination or expiration of the GI Product Promotion Term, it will discontinue
forthwith all use of the GI Product Trademarks with the GI Products, except in
the event a GI Product Trademark is assigned to Adolor pursuant to Section
16.10.4 or 16.12.4 or in the event that a GI Product Trademark is used in
connection with another GI Product or an Adolor Product in the United States
pursuant to Section 2.4.1. Subject to Sections 16.9.5, 16.10.4 and 16.12.4, to
the extent GSK licenses any of its intellectual property to Adolor under this
Agreement for trade dress purposes, Adolor acknowledges that nothing in this
Agreement shall give it any right, title or interest in such intellectual
property.

         2.4.3 ROW Trademarks. The Collaboration Products shall be
               --------------
Commercialized in the ROW under trademarks and trade dress selected by GSK (the
"ROW Trademarks"). GSK may select an Adolor Product Trademark or a GI Product
 --------------
Trademark for use in connection with a Collaboration Product in the ROW,
provided that GSK shall use its Commercially Reasonable Efforts to ensure that
such use is consistent with the use of such Adolor Product Trademark or GI
Product Trademark in the United States in connection with Collaboration
Products. In such case Adolor shall promptly take all steps necessary, at the
expense and direction of GSK, to assign the Adolor Product Trademarks for the
Country or Countries in the ROW for which GSK notifies Adolor it wishes to
utilize such Adolor Product Trademark in connection with such Collaboration
Product. After such assignment has been effected, the Adolor Product Trademark
to be used in such Country or Countries shall be deemed a ROW Trademark. Adolor
shall have no rights under this Agreement in or to the ROW Trademarks or the
goodwill pertaining thereto except as specifically provided herein.

                                      -20-

<PAGE>

         2.4.4 Trademark and Housemark Licenses.
               --------------------------------

               (a) Adolor hereby grants to GSK (i) a non-exclusive,
non-transferable (except in accordance with Section 2.3) license to use the
Adolor Housemark in the United States during the Adolor Product Promotion Term
solely in conjunction with the Adolor Products, (ii) an exclusive (except as to
Adolor and its Affiliates), non-transferable (except in accordance with Section
2.3) license to use the Adolor Product Trademarks in the United States during
the Adolor Product Promotion Term solely in conjunction with the Adolor
Products, (iii) a non-exclusive, non-transferable (except in accordance with
Section 2.3) license to use the Adolor Housemark in the United States during the
GI Product Promotion Term solely in conjunction with the GI Products, (iv) an
exclusive (except as to Adolor and its Affiliates), non-transferable (except in
accordance with Section 2.3) license to use the Adolor Product Trademarks in the
United States during the GI Product Promotion Term to the extent selected by GSK
in accordance with Sections 2.4.2 solely in conjunction with the GI Products,
and (v) a non-exclusive, non-transferable (except in accordance with Section
2.3) license to use the Adolor Housemark in the ROW solely in conjunction with
the Collaboration Products. All rights not expressly granted in the Adolor
Housemark and the Adolor Product Trademarks are reserved by Adolor and GSK
acknowledges that nothing in this Agreement shall give it any right, title or
interest in the Adolor Housemark or the Adolor Product Trademarks other than the
licenses granted herein.

               (b) GSK hereby grants to Adolor (i) a non-exclusive,
non-transferable (except in accordance with Section 2.3) license to use the GSK
Housemark in the United States during the GI Product Promotion Term solely in
conjunction with the GI Products, (ii) an exclusive (except as to GSK and its
Affiliates), non-transferable (except in accordance with Section 2.3) license to
use the GI Product Trademarks in the United States during the GI Product
Promotion Term solely in conjunction with the GI Products, (iii) a
non-exclusive, non-transferable (except in accordance with Section 2.3) license
to use the GSK Housemark in the United States during the Adolor Product
Promotion Term solely in conjunction with the Adolor Products, and (iv) an
exclusive (except as to GSK and its Affiliates), non-transferable (except in
accordance with Section 2.3) license to use the GI Product Trademarks in the
United States to the extent selected by Adolor in accordance with Section 2.4.1,
subject to Section 16.9.5, solely in conjunction with the Adolor Products. All
rights not expressly granted in the GSK Housemark and the GI Product Trademarks
are reserved by GSK and Adolor acknowledges that nothing in this Agreement shall
give it any right, title or interest in the GSK Housemark or the GI Product
Trademarks other than the license granted herein.

                  (c)  The Parties shall use the Adolor Housemark, GSK
Housemark, the Adolor Product Trademarks, the GI Product Trademarks and the ROW

                                      -21-

<PAGE>

Trademarks with the necessary trademark designations and the Parties shall use
Commercially Reasonable Efforts to use the respective Adolor Housemark or GSK
Housemark, the Adolor Product Trademarks, the GI Product Trademarks and the ROW
Trademarks in a manner that does not derogate from the Parties' rights in the
respective trademarks, names and logos and the Parties will take no action that
will interfere or diminish the Parties' rights in their respective trademarks,
names and logos. The Parties agree that all use of the other's trademarks, names
and logos will inure to the benefit of the owner of such trademarks, names and
logos.

           2.4.5  Marking of Promotional Materials.
                  --------------------------------

                  (a)  In the United States, to the extent permitted by
applicable Laws, the Adolor Housemark and the GSK Housemark shall be given equal
exposure and prominence on all Promotional Materials, labeling, package inserts
or outserts and packaging for the Adolor Products or samples of Adolor Products
during the Adolor Product Promotion Term and GI Products or samples of GI
Products during the GI Product Promotion Term.

                  (b)  In the ROW, to the extent permitted by applicable Laws,
the Adolor Housemark and the GSK Housemark shall be given equal exposure and
prominence on all labeling, package inserts or outserts and packaging for the
Collaboration Products or Samples during the ROW Term.

                  (c)  If any Claim for infringement is brought against a Party
alleging that its use of the other Party's housemark infringes the intellectual
property of a Third Party, the Party with the alleged infringing housemark shall
be responsible for defending such claim and for paying all costs associated with
such defense and shall indemnify and hold harmless the other Party and its
Affiliates and each of their officers, directors, shareholders, employees,
successors and assigns from and against all Losses arising out of or relating to
such Claim.

           2.4.6  Non-Use of Similar Marks. Notwithstanding any other provision
                  ------------------------
in this Agreement, during each of the Adolor Product Promotion Term, GI Product
Promotion Term or ROW Term, neither Party nor its Affiliates shall market,
promote, sell and/or distribute any product (other than the Adolor Product, GI
Products or Collaboration Products, as the case may be) under the Adolor Product
Trademarks, the GI Product Trademarks or the ROW Trademarks or any substantially
similar trade names or trademarks.

           2.4.7  Trademark Filings and Expenses. Adolor shall be solely
                  ------------------------------
responsible for the filing and maintenance of the Adolor Product Trademarks in
the United States and all costs and expenses related thereto. GSK shall be
solely responsible for the filing and maintenance of (a) the GI Product
Trademarks in the United States, and (b) the ROW Trademarks in the ROW, and all
costs and expenses related thereto.

                                      -22-

<PAGE>

           2.4.8   Trademark Infringement.
                   ----------------------

                  (a)  Infringement Claims by Third Parties. With respect to any
                       ------------------------------------
and all Claims instituted by Third Parties against Adolor or GSK or any of their
respective Affiliates for trademark infringement involving the use, sale,
license or marketing of a Collaboration Product in the United States during the
United States Term (each, a "Trademark Infringement Claim"), ** and Adolor and
                             ----------------------------
GSK will assist one another and cooperate in the defense and settlement of such
Trademark Infringement Claims at the other Party's request; provided, however,
that in all cases referred to in this Section 2.4.8, neither Party shall be
liable for any proportion of its share of the Losses in relation to the
Trademark Infringement Claim **.

                  (b)  Infringement of Adolor Product Trademarks. In the event
                       -----------------------------------------
that Adolor or GSK becomes aware of actual or threatened infringement of an
Adolor Product Trademark during the Term, that Party will promptly notify the
other Party in writing (a "Trademark Infringement Notice"). Adolor will have the
                           -----------------------------
right but not the obligation to bring an action with respect to such
infringement against any Third Party for infringement of an Adolor Product
Trademark. Adolor shall exercise this first right **. During the Term, in the
event that Adolor does not undertake such an infringement action with respect to
an Adolor Product Trademark, upon Adolor's written consent, which shall not be
unreasonably withheld, refused, conditioned or delayed, GSK shall be

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -23-

<PAGE>

permitted to do so. If Adolor has consented to an infringement action but GSK is
not recognized by the applicable court or other relevant body as having the
requisite standing to pursue such action, then GSK may join Adolor as
party-plaintiff. If GSK elects to pursue such infringement action, Adolor may
**.

                  (c)  Infringement of GI Product Trademarks. In the event that
                       -------------------------------------

GSK or Adolor becomes aware of actual or threatened infringement of a GI Product
Trademark during the Term, that Party will promptly notify the other Party in
writing. GSK will have the right but not the obligation to bring an action with
respect to such infringement against any Third Party for infringement of a GI
Product Trademark. GSK shall exercise this first right **. During the Term, in
the event that GSK does not undertake such an infringement action with respect
to a GI Product Trademark, upon GSK's written consent, which shall not be
unreasonably withheld, refused, conditioned or delayed, Adolor shall be
permitted to do so. If GSK has consented to an infringement action but Adolor is
not recognized by the applicable court or other relevant body as having the
requisite standing to pursue such action, then GSK may be joined as a
party-plaintiff. If Adolor elects to pursue such infringement action, GSK may **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -24-

<PAGE>

**.

                  (d)  Infringement of ROW Trademarks.
                       ------------------------------

                       (i)   In the event that GSK or Adolor becomes aware of
actual or threatened infringement of a ROW Trademark during the ROW Term, that
Party will promptly notify the other Party in writing.

                       (ii)  With respect to **.

                       (iii) With respect to **. During the Term, in the event
that GSK does not undertake such an infringement action with respect to **, upon
GSK's written consent, which shall not be unreasonably withheld, refused,
conditioned or delayed, Adolor shall be permitted to do so. If GSK has consented
to an infringement action but Adolor is not recognized by the applicable court
or other relevant body as having the requisite standing to pursue such action,
then GSK may be joined as a party-plaintiff. If Adolor elects to pursue such
infringement action, GSK may **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -25-

<PAGE>

**

                  (e)  Infringement of Adolor Housemark or GSK Housemark. In the
                       -------------------------------------------------
event that GSK or Adolor becomes aware of actual or threatened infringement of
the other Party's housemark during the Term, that Party will promptly notify the
other Party in writing. Each Party will have the right but not the obligation to
bring an infringement action against any Third Party in relation to such
infringement of their respective housemark. **

     2.5   Intellectual Property.
           ---------------------

           2.5.1  No Other GSK Rights. Except for the express rights granted to
                  -------------------
GSK in this Agreement, GSK shall not enjoy or exercise any proprietary or
property right or otherwise have any other right, title or interest in the
Adolor Product Trademarks, the Adolor Housemark, the Adolor Inventions, the
Adolor Patents, the Adolor Know-How or in any copyright owned by Adolor or any
of its Affiliates, and GSK shall not represent to any Third Party that it has
any such proprietary or property right, or any other right, title or interest.

           2.5.2  No Other Adolor Rights. Except for the express rights granted
                  ----------------------
to Adolor in this Agreement, Adolor shall not enjoy or exercise any proprietary
or property right or otherwise have any other right, title or interest in the
GSK Housemark, the GI Product Trademarks, the ROW Trademarks, the GSK
Inventions, the GSK Patents, the GSK Know-How or in any copyright owned by GSK
or any of its Affiliates, and Adolor shall not represent to any Third Party that
it has any such proprietary or property right, or any other right, title or
interest.

           2.5.3  Ownership of Inventions. Each Party shall promptly disclose to
                  -----------------------
the other Party all Inventions made by it during the Term. Adolor shall own all
Adolor Inventions and GSK shall own all GSK Inventions. All Joint Inventions
shall be owned jointly by Adolor and GSK, and each Party hereby consents to the
assignment or license or other disposition by the other Party of its joint
interests in Joint Inventions without the need to seek the consent of the other
Party to such assignment or license or other disposition; provided that any such
assignment, license or other disposition shall at all times be subject to the
grant of rights under Sections 2.1 and 2.2. The determination of inventorship
for Inventions shall be made in accordance with applicable laws relating to
inventorship set forth in the patent laws of the United States (Title 35, United
States Code).

     2.6   Exclusivity.**
           -----------

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -26-

<PAGE>

**

     2.7   OTC Rights. During the United States Term or ROW Term, as the case
           ----------
may be, on a Collaboration Product-by-Collaboration Product basis, Adolor will
not seek to switch a Collaboration Product from prescription status to OTC
status without the prior written consent of GSK. If Adolor intends to directly
or indirectly sell or offer for sale in collaboration with a Third Party (a) any
Collaboration Product as an OTC product in the United States within ** (**)
years following expiration of the United States Term or (b) any Collaboration
Product in the ROW within ** (**) years following expiration of the ROW Term,
then at least ** (**) days prior to taking substantial steps toward
developing such Collaboration Product as an OTC Product, Adolor shall give GSK
notice of such intention, and for the ** (**) day period following delivery
of such notice, the Parties shall negotiate exclusively with each other
commercial terms under which Adolor and GSK would Commercialize such
Collaboration Product as an OTC Product. Neither Party shall be obligated to
agree upon any such terms or to accept any terms proposed by the other Party.

                                   ARTICLE 3
                          GOVERNANCE OF DEVELOPMENT AND
                          COMMERCIALIZATION OF PRODUCTS

     3.1   Joint Steering Committee.
           ------------------------

           3.1.1  Members; Officers. Within thirty (30) days after the Effective
                  -----------------
Date, the Parties shall establish a joint steering committee (the "Joint
                                                                   -----
Steering Committee"), which shall consist of six (6) members, three (3) of whom
------------------

shall be designated by each of GSK and Adolor and shall have appropriate
expertise, with at least two (2) members from each Party being at least at a
vice president level. Each of GSK and Adolor may replace any or all of its
representatives on the Joint Steering Committee at any time upon written notice
to the other Party. A Party may designate a substitute to temporarily attend and
perform the functions of such Party's designee at any meeting of the Joint
Steering Committee. GSK and Adolor each may, on advance written notice to the
other Party, invite non-member representatives of such Party to attend meetings
of the Joint Steering Committee. The Joint Steering Committee shall be chaired
on an annual rotating basis by a representative of either Adolor or GSK, as
applicable, on the Joint Steering Committee, with Adolor providing the first
such chairperson. The chairperson shall appoint a secretary of the Joint
Steering Committee, who shall be a

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the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -27-

<PAGE>

representative of the other Party and who shall serve for the same annual term
as such chairperson.

               3.1.2  Responsibilities. The Joint Steering Committee shall
                      ----------------
perform the following functions:

                      (a)  Manage and oversee the Development and
Commercialization of the Collaboration Products in the United States pursuant to
the terms of this Agreement;

                      (b)  Review and approve the U.S. Development Plans and the
U.S. Marketing Plans for Collaboration Products and any material amendments to
the U.S. Development Plans and U.S. Marketing Plans;

                      (c)  Coordinate Development and Commercialization of the
Collaboration Products in the ROW with the Development and Commercialization of
the Collaboration Products in the United States with appropriate liaison with
the Joint Development Committee and the Joint Marketing Committee;

                      (d)  At each meeting of the Joint Steering Committee,
review a comparison of actual Development Expenses and Marketing Expenses for
the United States to the budgeted Development Expenses and Marketing Expenses
for the United States for the year-to-date, as current as practicable to a date
immediately prior to the date of the meeting;

                      (e)  Review and approve the progress of the other
committees;

                      (f)  Review and approve the trademarks selected under
Section 2.4;

                      (g)  Review and approve "go/no-go" decisions and other
matters referred to the Joint Steering Committee, including, without limitation,
the continued Development of a particular Collaboration Product or the inclusion
of Additional Products;

                      (h)  Life cycle management of, and intellectual property
protection for, the Collaboration Products in the United States;

                      (i)  Approve any and all ** policies and ** in the ** for
Collaboration Products, including **;

                      (j)  In accordance with the procedures established in
Section 3.1.4, resolve disputes, disagreements and deadlocks unresolved by the
other committees; and

                      (k)  Have such other responsibilities as may be assigned
to the Joint Steering Committee pursuant to this Agreement or as may be mutually
agreed upon by the Parties from time to time.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -28-

<PAGE>

               3.1.3  Meetings. The Joint Steering Committee shall meet in
                      --------
person at least three (3) times during every Calendar Year, and more frequently
as GSK and Adolor deem appropriate or as required to resolve disputes,
disagreements or deadlocks in the other committees, on such dates, and at such
places and times, as such Parties shall agree; provided that the Parties shall
endeavor to have the first meeting of the Joint Steering Committee within thirty
(30) days after the establishment of the Joint Steering Committee. The Joint
Steering Committee shall arrange to meet in person or convene otherwise to
assess and approve any U.S. Development Plans or U.S. Marketing Plans, if any,
submitted to the Joint Steering Committee in each Calendar Year so that such
plans will be reviewed and approved within thirty (30) days following submission
to the Joint Steering Committee. To the extent any such U.S. Development Plans
or U.S. Marketing Plans are not approved and need to be reformulated by the
Joint Development Committee or Joint Marketing Committee, such plans shall be
reviewed by the Joint Steering Committee as soon as reasonably practicable after
resubmission of same. Meetings of the Joint Steering Committee that are held in
person shall alternate between offices of GSK and Adolor, or such other place as
such Parties may agree. The members of the Joint Steering Committee also may
convene or be polled or consulted from time to time by means of
telecommunications, video conferences, electronic mail or correspondence, as
deemed necessary or appropriate.

               3.1.4  Decision-Making.
                      ---------------

                      (a)  The Joint Steering Committee may make decisions with
respect to any subject matter that is subject to the Joint Steering Committee's
decision-making authority and functions as set forth in Section 3.1.2. Except as
specified in Section 3.1.4(b), all decisions of the Joint Steering Committee
shall be made by unanimous vote or written consent, with GSK and Adolor each
having, collectively, among its respective members, one vote in all decisions.
The Joint Steering Committee shall use Commercially Reasonable Efforts to
resolve the matters within its roles and functions or otherwise referred to it.

                      (b)  With respect to any issue, if the Joint Steering
Committee cannot reach consensus within ten (10) Business Days after the matter
has been brought to the Joint Steering Committee's attention, then such issue
shall be referred to the Chief Executive Officer of Adolor and the Chairman R&D
of GSK for Development issues and the Chief Executive Officer of Adolor and the
President (U.S.) of GSK for Commercialization issues (the "Officers") for
                                                           --------
resolution.**

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -29-

<PAGE>

**.
                      (c)  Notwithstanding any other provision of this Agreement
to the contrary, the decision to ** shall require the unanimous consent of the
Joint Steering Committee, and such issue shall not be subject to the dispute
resolution provision of Sections 18.5.2 and 18.5.3.

               3.2    Joint Development Committee.
                      ---------------------------

                      3.2.1  Members; Officers. Within thirty (30) days after
                             -----------------
the Effective Date, the Parties shall establish a Development Committee (the
"Joint Development Committee"), and GSK and Adolor shall designate an equal
 ---------------------------
number of representatives, up to a maximum total of eight (8) members on such
Joint Development Committee. Each of GSK and Adolor may replace any or all of
its representatives on the Joint Development Committee at any time upon written
notice to the other Party. Such representatives shall include individuals who
have clinical trial and regulatory experience and expertise in pharmaceutical
drug development. A Party may designate a substitute to temporarily attend and
perform the functions of such Party's designee at any meeting of the Joint
Development Committee. GSK and Adolor each may, on advance written notice to the
other Party, invite non-member representatives of such Party to attend meetings
of the Joint Development Committee. The Joint Development Committee shall be
chaired on an annual rotating basis by a representative of either Adolor or GSK,
as applicable, with Adolor providing the first such chairperson. The chairperson
shall appoint a secretary of the Joint Development Committee, who shall be a
representative of the other Party and who shall serve for the same annual term
as such chairperson.

                      3.2.2  Responsibilities.  The Joint Development Committee
                             ----------------
shall perform the following functions:

                             (a)  Manage and oversee the preparation and
implementation of the U.S. Development Plans;

                             (b)  As early as necessary in each year beginning
with the first full Calendar Year after the Effective Date, update and amend the
initial U.S. Development Plans and prepare the U.S. Development Plans for each
Collaboration Product for the following Calendar Year so that it can submit such
proposed U.S. Development Plans to the Joint Steering Committee no later than
** of such year for review and approval;

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the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

                             (c)  Prepare the Development strategy and develop
protocols for clinical studies for the Collaboration Products for
Commercialization in the United States;

                             (d)  Review and recommend to the Joint Steering
Committee any material amendments or modifications to the U.S. Development
Plans;

                             (e)  Coordinate and monitor regulatory strategy and
activities for the Collaboration Products in accordance with Article 9;

                             (f)  At each meeting of the Joint Development
Committee, review a comparison of actual Development Expenses for the United
States to the budgeted Development Expenses for the United States in the U.S.
Development Plan for the year-to-date, as current as practicable to a date
immediately prior to the date of the meeting;

                             (g)  Review and recommend to the Joint Steering
Committee "go/no-go" decisions for the Development of Collaboration Products in
the United States; and

                             (h)  Have such other responsibilities as may be
assigned to the Joint Development Committee pursuant to this Agreement or as may
be mutually agreed upon by the Parties from time to time.

               3.2.3  Meetings. The Joint Development Committee shall meet in
                      --------
person at least once during every Calendar Quarter, and more frequently as GSK
and Adolor deem appropriate or as reasonably requested by either such Party, on
such dates, and at such places and times, as such Parties shall agree; provided
that the Parties shall endeavor to have the first meeting of the Joint
Development Committee within thirty (30) days after the establishment of the
Joint Development Committee. Meetings of the Joint Development Committee that
are held in person shall alternate between the offices of GSK and Adolor, or
such other place as the Parties may agree. The members of the Joint Development
Committee also may convene or be polled or consulted from time to time by means
of telecommunications, video conferences, electronic mail or correspondence, as
deemed necessary or appropriate.

               3.2.4  Development Budget. The Joint Development Committee shall
                      ------------------
review on a quarterly basis the actual Development Expenses against the budget
for such expenses in the applicable Calendar Year. If in the course of its
quarterly review of Development Expenses, the Joint Development Committee should
determine for any Collaboration Product that for any study or activity the
actual amounts incurred are likely to be higher than budgeted, the Joint
Development Committee shall review the reasons for such potential overrun and
determine whether such overrun is appropriate. If the Joint Development
Committee determines that such overrun is appropriate, the Joint Development
Committee will assess whether such overrun is likely to result in an overrun of
the budget for Development

                                      -31-

<PAGE>

Expenses for such Collaboration Product and if required, will agree on a revised
budget for such Development Expenses for such Collaboration Product for
subsequent approval by the Joint Steering Committee. If the Joint Development
Committee determines that such overrun is not appropriate, the Joint Development
Committee will take such actions as required to remedy the situation.

               3.2.5  Decision-Making. The Joint Development Committee may make
                      ---------------
decisions with respect to any subject matter that is subject to the Joint
Development Committee's decision-making authority and functions as set forth in
Section 3.2.2. All decisions of the Joint Development Committee shall be made by
unanimous vote or written consent, with GSK and Adolor each having collectively,
among its respective members, one vote in all decisions. If the Joint
Development Committee cannot reach consensus within ** (**) Business Days after
it has first met and attempted to reach such consensus, the matter shall be
referred on the ** (**) Business Day to the Joint Steering Committee for
resolution.

        3.3    Joint Marketing Committee.
               -------------------------

               3.3.1  Members; Officers. Within thirty (30) days after the
                      -----------------
Effective Date, the Parties shall establish a commercialization committee (the
"Joint Marketing Committee"), and GSK and Adolor shall designate an equal number
 -------------------------
of representatives, up to a maximum total of eight (8) members on the Joint
Marketing Committee. Each of GSK and Adolor may replace any or all of its
representatives on the Joint Marketing Committee at any time upon written notice
to the other. Such representatives shall include individuals who have experience
and expertise in pharmaceutical product marketing, sales and regulatory matters.
A Party may designate a substitute to temporarily attend and perform the
functions of such Party's designee at any meeting of the Joint Marketing
Committee. GSK and Adolor each may, upon prior written notice to the other
Party, invite non-member representatives of such Party to attend meetings of the
Joint Marketing Committee. The Joint Marketing Committee shall be chaired on an
annual rotating basis by a representative of either Adolor or GSK, as applicable
with GSK providing the first such chairperson. The chairperson shall appoint a
secretary of the Joint Marketing Committee, who shall be a representative of the
other Party and who shall serve for the same annual term as such chairperson.

               3.3.2  Responsibilities.  The Joint Marketing Committee shall
                      ----------------
perform the following functions:

                      (a)  Manage and oversee the preparation and implementation
of the U.S. Marketing Plans;

                      (b)  Review and recommend to the Joint Steering Committee
any material amendments or modifications to the U.S. Marketing Plans, including
those pursuant to Section 5.1.6;

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

                      (c)  Coordinate and monitor regulatory strategy and
activities for Phase IV Studies in support of Collaboration Products that are
Commercialized in the United States in accordance with Article 9;

                      (d)  Make any changes to the Target Audience; provided,
however, the Parties shall not be required to implement such changes within one
hundred eighty (180) days of such change;

                      (e)  Discuss the state of the markets for Collaboration
Products in the United States and opportunities and issues concerning the
Commercialization of the Collaboration Products in the United States, including
consideration of marketing and promotional strategy, marketing research plans,
labeling, Collaboration Product positioning and Collaboration Product profile
issues, to determine the kind of marketing and selling efforts that are
appropriate, in accordance with the U.S. Marketing Plans;

                      (f)  Review data and reports arising from and generated in
connection with the Commercialization of the Collaboration Products in the
United States, including, but not limited to the U.S. Marketing Plans, marketing
budgets and sales forecasts;

                      (g)  At each meeting of the Joint Marketing Committee,
review a comparison of actual sales and Marketing Expenses in the United States
to the budgeted Sales and Marketing Expenses in the relevant U.S. Marketing Plan
for the year-to-date, as current as practicable to a date immediately prior to
the date of the meeting;

                      (h)  Review and approve the general guidelines applicable
to particular Collaboration Products to be followed for Promotional Materials to
be used by Adolor and GSK in the promotion of such Collaboration Products (such
guidelines to be consistent with then current U.S. Marketing Plan applicable to
such Collaboration Products); and

                      (i)  Have such other responsibilities as may be assigned
to the Joint Marketing Committee pursuant to this Agreement or as may be
mutually agreed upon by the Parties from time to time.

           3.3.3  Meetings. The Joint Marketing Committee shall meet in person
                  --------
at least once during every Calendar Quarter, and more frequently as GSK and
Adolor deem appropriate or as reasonably requested by either such Party, on such
dates, and at such places and times, as such Parties shall agree; provided that
the Parties shall endeavor to have the first meeting of the Joint Marketing
Committee within thirty (30) days after the establishment of the Joint Marketing
Committee. Meetings of the Joint Marketing Committee that are held in person
shall alternate between the offices of GSK and Adolor, or such other place as
such Parties may agree. The members of the Joint Marketing Committee also may
convene or be polled or

                                      -33-

<PAGE>

consulted from time to time by means of telecommunications, video conferences,
electronic mail or correspondence, as deemed necessary or appropriate.

           3.3.4  Marketing Budget. The Joint Marketing Committee shall review
                  ----------------
on a quarterly basis the actual Marketing Expenses against the budget for such
expenses in the applicable Calendar Year. If in the course of its quarterly
review of Marketing Expenses, the Joint Marketing Committee should determine for
any Collaboration Product that for any study or activity the actual amounts
incurred are likely to be higher than budgeted, the Joint Marketing Committee
shall review the reasons for such potential overrun and determine whether such
overrun is appropriate. If the Joint Marketing Committee determines that such
overrun is appropriate, the Joint Marketing Committee will assess whether such
overrun is likely to result in an overrun of the budget for Marketing Expenses
for such Collaboration Product on an annual basis and if required, will agree on
a revised budget for such Marketing Expenses for such Collaboration Product for
subsequent approval by the Joint Steering Committee. If the Joint Marketing
Committee determines that such overrun is not appropriate, the Joint Marketing
Committee will take such actions as required to remedy the situation.

           3.3.5  Decision-Making. The Joint Marketing Committee may make
                  ---------------
decisions with respect to any subject matter that is subject to the Joint
Marketing Committee's decision-making authority and functions as set forth in
Section 3.3.2. All decisions of the Joint Marketing Committee shall be made by
unanimous vote or written consent, with GSK and Adolor each having collectively,
among its respective members, one vote in all decisions. If the Joint Marketing
Committee cannot reach consensus within ** (**) Business Days after it has first
met and attempted to reach such consensus, the matter shall be referred on the
** (**) Business Day to the Joint Steering Committee for resolution.

     3.4   Joint Supply Committee.
           ----------------------

           3.4.1  Members; Officers. Within thirty (30) days after the Effective
                  -----------------
Date, the Parties shall establish a supply committee (the "Joint Supply
                                                           ------------
Committee"), and GSK and Adolor shall designate an equal number of
---------
representatives, up to a maximum total of eight (8) members on such Joint Supply
Committee. Each of GSK and Adolor may replace any or all of its representatives
on the Joint Supply Committee at any time upon written notice to the other
Party. Such representatives shall include individuals who have supply chain
management experience. A Party may designate a substitute to temporarily attend
and perform the functions of such Party's designee at any meeting of the Joint
Supply Committee. GSK and Adolor each may, on advance written notice to the
other Party, invite non-member representatives of such Party to attend meetings
of the Joint Supply Committee. The Joint Supply Committee shall be chaired on an
annual rotating basis by a representative of either Adolor or GSK, as
applicable, with GSK providing the first such chairperson. The chairperson shall
appoint a secretary of the Joint Supply Committee, who shall be a representative
of the other Party and who shall serve for the same annual term as such
chairperson.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

           3.4.2  Responsibilities.  The Joint Supply Committee shall perform
                  ----------------
the following functions:

                  (a)  Manage and oversee the activities in relation to
manufacture and supply of API Compound and Collaboration Products for use in
Development and Commercialization and establish procedures and protocols for
testing API Compound and Collaboration Products to ensure that such API Compound
and Collaboration Products comply with the specifications (the "Testing
                                                                -------
Protocol"). The Parties will utilize such Testing Protocol with respect to API
--------
Compound and Collaboration Product that they may receive from Product Suppliers
to ensure that such API Compound or Collaboration Product meets specifications;

                  (b)  Recommend and coordinate necessary adjustments to the
manufacturing schedule to ensure it is meeting the needs for all Collaboration
Products;

                  (c)  Coordinate allocation of API Compound in the event of a
shortage between the United States and the ROW, it being understood that, in the
event of a shortage, allocation of API Compound shall be as follows:**;

                  (d)  Review the quality of the manufacture of the
Collaboration Products, reviewing as appropriate reports of the manufacturers of
API Compound and Collaboration Products and reports as to the quality of any
packaging that bears the relevant trademarks or housemarks of the Parties (as
owned by or licensed to the relevant Party under Section 2.4) as prescribed by
this Agreement;

                  (e)  Recommend and implement optimal inventory levels and
safety stock targets;

                  (f)  Set improvement targets and monitor performance against
these targets for cost, yield, delivery and other appropriate measures;

                  (g)  Establish guidelines to facilitate improved efficiencies
and compliance with current Good Manufacturing Practices by Product Suppliers;
and

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -35-

<PAGE>

                  (h)  Have such other responsibilities as may be assigned to
the Joint Supply Committee pursuant to this Agreement or as may be mutually
agreed upon by the Parties from time to time.

           3.4.3  Meetings. The Joint Supply Committee shall meet in person at
                  --------
least once during every Calendar Quarter, and more frequently as GSK and Adolor
deem appropriate or as reasonably requested by either such Party, on such dates,
and at such places and times, as such Parties shall agree; provided that the
Parties shall endeavor to have the first meeting of the Joint Supply Committee
within thirty (30) days after the establishment of the Joint Supply Committee.
Meetings of the Joint Supply Committee that are held in person shall alternate
between the offices of GSK and Adolor, or such other place as the Parties may
agree. The members of the Joint Supply Committee also may convene or be polled
or consulted from time to time by means of telecommunications, video
conferences, electronic mail or correspondence, as deemed necessary or
appropriate.

           3.4.4  Decision-Making. The Joint Supply Committee may make
                  ---------------
decisions with respect to any subject matter that is subject to the Joint Supply
Committee's decision-making authority and functions as set forth in Section
3.4.2. All decisions of the Joint Supply Committee shall be made by unanimous
vote or written consent, with GSK and Adolor each having collectively, among its
respective members, one vote in all decisions. If the Joint Supply Committee
cannot reach consensus within ** (**) Business Days after it has first met and
attempted to reach such consensus, the matter shall be referred on the ** (**)
Business Day to the Joint Steering Committee for resolution. Notwithstanding the
foregoing, any matter relating to supply of API Compound or any Collaboration
Product assigned for decision-making to a Party in Article 10 or in the further
agreements between the Parties contemplated thereby shall not be subject to
referral to the Joint Steering Committee.

     3.5   Minutes of Committee Meetings.  Definitive minutes of all committee
           -----------------------------
meetings shall be finalized no later than thirty (30) days after the meeting to
which the minutes pertain as follows:

           3.5.1  Distribution of Minutes. Within ten (10) days after a
                  -----------------------
committee meeting, the secretary of such committee shall prepare and distribute
to all members of such committee draft minutes of the meeting. Such minutes
shall provide a list of any issues yet to be resolved, either within such
committee or through the relevant resolution process.

           3.5.2  Review of Minutes. The Party members of each committee shall
                  -----------------
have ten (10) days after receiving such draft minutes to collect comments
thereon and provide them to the secretary of such committee.

           3.5.3  Discussion of Comments. Upon the expiration of such second ten
                  ----------------------
(10) day period, the Parties shall have an additional ten (10) days to discuss
each other's comments and finalize the minutes. The secretary and chairperson(s)
of such

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -36-

<PAGE>

committee shall each sign and date the final minutes. The signature of such
chairperson(s) and secretary upon the final minutes shall indicate each Party's
assent to the minutes.

     3.6   Expenses. Each Party shall be responsible for all travel and related
           --------
costs and expenses for its members and other representatives to attend meetings
of, and otherwise participate on, a committee.

     3.7   Initial Coordination Efforts. The Parties intend, following the
           ----------------------------
Effective Date, to organize meetings of internal staff to communicate and
explain the provisions of this Agreement to ensure the efficient and timely
Development and Commercialization of the Collaboration Products.

                                    ARTICLE 4
                             DEVELOPMENT OF PRODUCTS

     4.1   Responsibilities of the Parties. Subject to the general oversight of
           -------------------------------
the Joint Development Committee, and subject in all instances to the specific
provisions relating to regulatory matters referred to in Article 9:

           4.1.1  Adolor Products. Adolor shall have the overall responsibility
                  ---------------
for the performance of all Development activities, including regulatory filings,
for each Adolor Product that is required to obtain Marketing Authorization for
the Adolor Products in the United States and, in furtherance thereof, the
Parties shall perform the Development activities, all in accordance with the
applicable U.S. Development Plan, for an Adolor Product. The Parties acknowledge
that Adolor is in the process of conducting clinical studies on the POI Product
necessary to file the NDA.

           4.1.2  OBD Chronic Product. GSK shall have the overall responsibility
                  -------------------
for the performance of all Development activities, including regulatory filings,
of the OBD Chronic Product that is required to obtain Marketing Authorization
for the OBD Chronic Product in the United States and, in furtherance thereof,
the Parties shall perform Development activities, all in accordance with the
applicable U.S. Development Plan, for the OBD Chronic Product. The Parties
acknowledge that Adolor is in the process of conducting clinical studies on the
OBD Chronic Product necessary to file the NDA and such activities **. To the
extent such transfer is not timely made, the time period of any delay in
transfer shall toll the timeline for Development of the OBD Chronic Product as
set forth in the applicable U.S. Development Plan.

           4.1.3  Other GI Products. GSK shall be solely responsible for the
                  -----------------
performance of all Development activities, including regulatory filings, for
each GI Product (other than the OBD Chronic Product covered in Section 4.1.2)
that is required to obtain Marketing Authorization in the United States for such
GI Products in accordance with the applicable U.S. Development Plan for such GI
Products.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

     4.2   Obligations for Development.
           ---------------------------

           4.2.1  General. The Parties shall use Commercially Reasonable Efforts
                  -------
to Develop the Collaboration Products for Commercialization.

           4.2.2  GSK's Obligations. In furtherance of the foregoing, and
                  -----------------
subject to GSK's termination rights pursuant to Article 16 (including those
safety related termination rights pursuant to Section 16.4), **.

     4.3   Additional Products. At any time after the Effective Date, either
           -------------------
Party may make a written proposal to the Joint Development Committee regarding
the Development of an Additional Product. Such proposal shall include (i) any
data and other information in its possession which may be relevant to the use of
the proposed Product, (ii) a reasonably detailed outline of the major
Development activities required to obtain Marketing Authorization for such
proposed Product in the United States, including a timeline for performing such
activities, (iii) an estimated budget for the expected Development Expenses and
Marketing Expenses for such proposed Product, (iv) an appropriate market
analysis of the proposed Product (including market size, competitive analysis,
etc.), and (v) preliminary sales forecasts and estimated Cost of Goods for the
proposed Product. Thereafter, the Joint Development Committee shall meet in
order to review such proposal.

           4.3.1  Inclusion of Additional Products. With respect to a proposal
                  --------------------------------
pursuant to Section 4.3, if the Joint Development Committee accepts, or if the
Joint Development Committee cannot agree and the Joint Steering Committee
unanimously accepts, such proposal, such proposed Product shall be an Additional
Product, and the Joint Development Committee shall prepare a U.S. Development
Plan for such Additional Product. The Joint Development Committee shall also at
the same time designate such Additional Product as either an Adolor Product or a
GI Product, it being understood that the ** Product and any other Additional
Product that is to be primarily promoted to or used by health care providers in

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -38-

<PAGE>

hospitals shall be designated an Adolor Product, unless otherwise mutually
agreed by the Parties. In the event of disagreement between the Parties
regarding the inclusion of an Additional Product within the Joint Development
Committee such that the matter is referred to the Joint Steering Committee, the
Joint Steering Committee must agree unanimously upon its inclusion even if such
proposed Additional Product has already been designated by the Joint Development
Committee as an Adolor Product or a GI Product as contemplated under this
Section 4.3.1 and, therefore, the provisions of Section 3.1.4(b) shall not
apply.

           4.3.2  Disagreement Regarding Additional Product. If the Joint
                  -----------------------------------------
Development Committee or the Joint Steering Committee, as the case may be, does
not accept such proposal (unanimously in the case of the Joint Steering
Committee), such proposed Additional Product shall not become a Collaboration
Product; provided, however, if GSK proposes an Additional Product and Adolor
does not desire to Develop or Commercialize such proposed Additional Product in
the United States, GSK may Develop and Commercialize such proposed Additional
Product in the ROW subject to Section 4.3.3.

                  4.3.3  Independent Development and Commercialization of
                         ------------------------------------------------
Additional Products in the ROW.
------------------------------

                         (a)  If GSK desires to Develop and Commercialize a
proposed Additional Product in the ROW pursuant to Section 4.3.2, GSK may do so,
provided that:

                              (i)  the Development or Commercialization of such
Additional Product in ** does not ** on ** being Developed or Commercialized in
**; and

                              (ii) GSK takes into account the goal of optimizing
the best overall commercial potential of the Collaboration Products.

                         (b)  Subject to this Section 4.3.3, if GSK elects to
Develop or Commercialize such proposed Additional Products in the ROW, then (i)
such proposed Additional Products shall be referred to herein as a "GSK Other GI
                                                                    ------------
Product", (ii) GSK shall be solely responsible for all costs and expenses
-------
related to the Development and Commercialization in the ROW of such GSK Other GI
Product, and (iii) all provisions of this Agreement relating to Collaboration
Products in the ROW shall apply to such GSK Other GI Product.

                         (c)  Notwithstanding anything in the foregoing to the
contrary, the Development and Commercialization of the GSK Other GI Product in
the ROW shall be subject to the oversight of the Joint Development Committee,
Joint Marketing Committee and the Joint Steering Committee in accordance with
Sections 3.1.2(c).

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -39-

<PAGE>

           4.4    U.S. Development Plans.
                  ----------------------

                  4.4.1  Initial U.S. Development Plan for POI Product.  The
                         ---------------------------------------------
initial U.S. Development Plan for all Development activities for the POI
Product, which the Parties hereby approve, is attached to this Agreement as
Schedule 1.146.
--------------

                  4.4.2  Initial U.S. Development Plan for OBD Chronic Product.
                         -----------------------------------------------------
The initial U.S. Development Plan for all Development activities for the OBD
Chronic Product, which the Parties hereby approve, is attached to this Agreement
as Schedule 1.146. In the United States, the average total daily dose of
   --------------
Compound in an OBD Chronic Product recommended in the FDA approved label shall
be not more than one (1) milligram.

                  4.4.3  U.S. Development Plans for the ** Product and
                         ----------------------------------------------
** Product. As soon as practicable following the Effective Date, but in no event
later than sixty (60) days following the Effective Date, GSK shall prepare for
review by the Joint Development Committee and approval by the Joint Steering
Committee outlines of the U.S. Development Plan for the ** Product and of the
U.S. Development Plan for the ** Product. In the United States, the total daily
dose of Compound (in milligrams) in either the ** Product or the ** Product
shall be less than ** percent (**%) of the average total daily dose of Compound
(in milligrams) recommended in the FDA approved label in the POI Product. In the
event that a Collaboration Product other than the POI Product receives the first
Marketing Authorization Approval in the United States, then such percentage
limitation on dose of Compound shall be redefined by the Parties.

                  4.4.4  U.S. Development Plan for OBD Acute Product. The
                         -------------------------------------------
Parties acknowledge that Adolor is currently conducting clinical study ** in
connection with the Development of the POI Product and the cost of such study
will be included as a Development Expense for the purposes of Section 4.6.2. **.
If Adolor desires to proceed with the Development of the OBD Acute Product and
such Development will not or is not likely to **, Adolor shall so notify the
Joint Development Committee (of its desire to proceed with Development of the
OBD Acute Product and the reasons why such Development will not significantly or
adversely affect the commercial viability of the POI Product), and thereafter,
in accordance with Section 4.4.5, the Parties shall proceed with the Development
of the OBD Acute Product subject to Section 4.6.1. In the United States, the
total daily dose of Compound (in milligrams) in the OBD Acute Product shall not
be less than ** percent (**%) of the average total daily dose of Compound (in
milligrams) recommended in the FDA approved label in the POI Product. In the
event that a Collaboration Product other than the POI Product receives the first
Marketing Authorization Approval in the United States, then such percentage
limitation on dose of Compound shall be redefined by the Parties.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

                  4.4.5  U.S. Development Plans for Additional Products. When an
                         ----------------------------------------------
Additional Product is added as a Collaboration Product pursuant to Section 4.3,
within sixty (60) days following the date of such inclusion, for those
Additional Products designated Adolor Products, Adolor shall prepare, and for
those Additional Products designated GI Products, GSK shall prepare, for review
by the Joint Development Committee and approval by the Joint Steering Committee,
a U.S. Development Plan for each such Additional Product.

                  4.4.6  Updates to the U.S. Development Plans. As early as
                         -------------------------------------
necessary in each year beginning with the first full Calendar Year after the
Effective Date, the Joint Development Committee shall update and amend the
initial U.S. Development Plans and prepare the U.S. Development Plans for each
Collaboration Product for the following Calendar Year so that it can submit such
proposed U.S. Development Plans to the Joint Steering Committee no later than
** of such year for review and approval.

                  4.4.7  Criteria for U.S. Development Plans. The U.S.
                         -----------------------------------
Development Plan for each Collaboration Product shall contain at a minimum a
list and description of preclinical and clinical activities, timelines for the
performance of studies in support of the Development activities for such
Collaboration Product and a budget for the Development Expenses to complete such
Development activities.

            4.5   Implementation of U.S. Development Plans. Each Party will
                  ----------------------------------------
inform the Joint Development Committee of ongoing implementation of the U.S.
Development Plan and consider timely recommendations for improving the U.S.
Development Plan. In connection with the preparation and implementation of the
U.S. Development Plan, Adolor and GSK will make available to the Joint
Development Committee any information then in their possession pertaining to the
Collaboration Products useful for such Development activities.

            4.6   Development Funding.
                  -------------------

                  4.6.1  Development Budgets. The Development budgets for each
                         -------------------

Collaboration Product to be Commercialized in the United States shall be set
forth in the U.S. Development Plan for such Collaboration Product. Such
Development budget shall be sufficient to fund all necessary studies and related
activities necessary to obtain Marketing Authorization Approval for such
Collaboration Product. Notwithstanding the foregoing, unless otherwise agreed to
by the Parties, the total Development budget for an Adolor Product, the OBD
Chronic Product or for any other GI Product for which Adolor elects to fund
Development Expenses pursuant to Section 4.6.5, shall not ** percent (**%) of
the budget set forth in the most recently approved U.S. Development Plan for
such Collaboration Product. The budgets for the POI Product and the OBD Chronic
Product are set forth in the applicable U.S. Development Plan attached hereto as
Schedule 1.146. Subject to the percentage increase provisions of this Section
--------------
4.6.1, the initial Development budget for the OBD Acute Product shall not exceed
** United States Dollars (US$**).

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -41-

<PAGE>

                  4.6.2  Adolor Products in the United States. Subject to
                         ------------------------------------
reconciliation as provided in Section 6.7.5, Adolor shall be responsible and pay
for ** percent (**%) and GSK shall be responsible and pay for ** percent (**%)
of the Development Expenses for each Adolor Product for Commercialization in the
United States incurred from January 1, 2002 through the First Commercial Sale
for such Adolor Product. Thereafter, Development Expenses, if any, for each
Adolor Product shall be shared in accordance with **. With respect to the OBD
Acute Product, Adolor shall be solely responsible for (and such expenses shall
not be deemed Development Expenses) expenses related to the Development of the
OBD Acute Product incurred prior to the determination to proceed with the
Development of the OBD Acute Product in accordance with Section 4.4.4 other than
those expenses associated with clinical study 14CL306 which are set forth in
Schedule 1.146.
--------------

                  4.6.3  OBD Chronic Product and Other GI Products in the United
                         -------------------------------------------------------
States. Subject to reconciliation as provided in Section 6.7.5, Adolor shall be
------
responsible and pay for ** percent (**%) and GSK shall be responsible and pay
for ** percent (**%) of the Development Expenses in connection with the
Development of the OBD Chronic Product for Commercialization in the United
States incurred from January 1, 2002 through the First Commercial Sale for such
OBD Chronic Product as set forth in the U.S. Development Plan for the OBD
Chronic Product attached hereto as Schedule 1.146. Thereafter, Development
                                   --------------
Expenses, if any, for the OBD Chronic Product shall be shared in accordance with
**. Subject to Section 4.6.5, GSK shall have sole responsibility to pay for all
Development Expenses incurred in connection with the Development of any and all
other GI Products.

                  4.6.4  Payment of Expenses; Development Expense Account.
                         ------------------------------------------------
Unless otherwise agreed to by the Joint Development Committee, all Development
Expenses for the POI Product for Commercialization in the United States shall be
incurred by Adolor, subject to reimbursement as provided for herein. Subject to
each Party's relative percentage to fund Development Expenses set forth in this
Section 4.6 and reconciliation as provided in Section 6.7.5 and as set forth in
the preceding sentence, each Party shall be responsible to pay for all
Development Expenses incurred in performing its obligations in connection with
any Development activities under a U.S. Development Plan. Each Party shall
charge all such expenses so incurred to a separate account created by it on its
books and records solely for the purpose of tracking Development Expenses,
identifying all Development Expenses by Collaboration Product being Developed.

                  4.6.5  Election to Fund GI Products in the United States.
                         -------------------------------------------------

                         (a)  Notwithstanding Section 4.6.3, at Adolor's sole
and absolute discretion, Adolor may elect to fund ** percent (**%) of the
Development Expenses of any GI Product in the United States (other than the OBD

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -42-

<PAGE>

Chronic Product, which is set forth in Section 4.6.3) incurred from the
commencement of any ** Study for such GI Product (it being understood that the
studies and activities for such GI Product of the type set forth on Schedule
                                                                    --------
4.6.5A shall be included in the Development Expenses at ** percent (**%) of the
------
cost thereof in recognition of the applicability of such studies or activities
in the ROW as well as in the United States). As soon as practicable after
completion of all ** Studies, and a decision by GSK to proceed to a ** Study for
a GI Product, GSK shall provide Adolor for its review results of all such **
Studies and any updates to the most recent U.S. Development Plan, proposed **
Study protocols and a proposed U.S. Marketing Plan for such GI Product. Such
proposed U.S. Marketing Plan shall be subject to the procedures set forth in
Schedule 4.6.5B. Adolor's election to fund such Development Expenses of a GI
---------------
Product (which shall be made on a GI Product-by-GI Product basis) shall be made
by Adolor providing written notice to GSK of its election to fund Development
Expenses no more than thirty (30) Business Days after Adolor's receipt of all
such information. Adolor's obligations to fund such Development Expenses for any
GI Product pursuant to this Section 4.6.5 shall continue from the date of such
written notice unless and until Adolor makes a Royalty Conversion Election for
such GI Product as provided in Section 6.3.5. In the event that the dosage form
and strength for the ** Product and the ** Product are the same, then Adolor
shall make the same election with respect to funding Development Expenses in the
United States or making a Royalty Conversion Election for both the ** Product
and the ** Product.

                         (b)  In the event that Adolor has elected not to fund
** percent (**%) of such Development Expenses of a GI Product, then, within
ninety (90) days following the NDA Acceptance date with respect to such GI
Product, GSK shall provide to Adolor a report of the actual Development Expenses
for such GI Product through the conclusion of ** Studies. In the event that such
actual Development Expenses are less than ** percent (**%) of the proposed
budget as set forth in the information submitted by GSK under subsection (a)
above, Adolor shall have thirty (30) days after receipt of such report to elect
to pay GSK an amount equal to ** percent (**%) of the actual Development
Expenses incurred from the commencement of any ** Study for such GI Product and
thereby share in the GI Product Marketing Contribution for such GI Product in
accordance with Section 6.3.2 and subject to Adolor's right to make a Royalty
Conversion Election for such GI Product.

            4.7   Development in the ROW.
                  ----------------------

                  4.7.1  GSK Responsibility. GSK shall have sole responsibility
                         ------------------
for Developing Collaboration Products for Commercialization in the ROW. GSK
shall bear all

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the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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costs and expenses associated with the Development of Products for
Commercialization in the ROW.

                  4.7.2  ROW Development Plan; Coordination; Semi-Annual
                         -----------------------------------------------
Reports. As early as necessary in each year beginning with the first full
-------
Calendar Year after the Effective Date, GSK shall prepare a Development plan for
each Collaboration Product in the ROW (each, a "ROW Development Plan") so that
                                                --------------------
it can submit such ROW Development Plans to the Joint Steering Committee no
later than September 30 of such year for review. GSK shall coordinate its
Development activities for Collaboration Products in the ROW with the Joint
Development Committee and provide the Joint Development Committee semi-annual
reports within thirty (30) days after June 30 and December 31 of each Calendar
Year. Such reports shall set forth in summary form the results of GSK's
Development activities with respect to Collaboration Products for
Commercialization in the ROW performed during such semi-annual period and any
updates to such ROW Development Plan.

                  4.7.3  Decisions with Respect to Products in the ROW. Subject
                         ---------------------------------------------
to Section 3.1.4, GSK shall have the sole discretion with respect to Development
decisions for Collaboration Products for Commercialization in the ROW.

                  4.7.4  OBD Acute Product in the ROW. The total daily dose of
                         ----------------------------
Compound (in milligrams) in the OBD Acute Product Commercialized in the ROW
shall be ** the total daily dose of Compound (in milligrams) in the
label approved by the relevant Governmental Authority for the GI Products
Commercialized in the ROW.

            4.8   Fulfillment of Obligations. It is understood that, in
                  --------------------------
fulfilling its obligations under this Agreement, each Party shall be free to
fulfill its obligations within its existing organizational structure. Upon
mutual agreement of the Parties, representatives from a Party shall be entitled
to attend, on an observer basis, meetings of the other Party's internal working
groups responsible for the Development of the Collaboration Products.

            4.9   Transfer of Data. As soon as practicable but in no event more
                  ----------------
than thirty (30) days after the Effective Date, the Parties shall determine what
data and materials relating to Compound, GI Products and Adolor Products in the
ROW are necessary for GSK's Development obligations pursuant to this Article 4,
and establish a process for transferring copies of such data and material to GSK
(including, to the extent available, in appropriate electronic format) or
provide means of access thereto reasonably acceptable to GSK.

            4.10  Right to Audit. Each Party shall use Commercially Reasonable
                  --------------
FEfforts to ensure that the other Party's authorized representatives, and shall
ensure that Governmental Authorities, in both cases to the extent permitted by
applicable Law, may, during regular business hours, (a) examine and inspect its
facilities or, subject to any Third Party confidentiality restrictions or
obligations, the facilities of any subcontractor or any investigator site used
by it in the performance of Development of a Collaboration Product, and (b)
inspect and

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -44-

<PAGE>

copy all data, documentation and work products relating to the activities
performed by it or, subject to any Third Party confidentiality restrictions or
obligations, the subcontractor or investigator site, including, without
limitation, the medical records of any patient participating in any clinical
study. This right to inspect and copy all data, documentation, and work products
relating to a Collaboration Product may be exercised at any time during the Term
(subject to each Party's record retention policies then in effect), or such
longer period as shall be required by applicable Law.

                                    ARTICLE 5
                  CO-PROMOTION, DETAILING AND COMMERCIALIZATION

     5.1  U.S. Marketing Plans.
          --------------------

          5.1.1  General. The Joint Marketing Committee shall be responsible for
                 -------
preparing and implementing a U.S. Marketing Plan for each Collaboration Product.
Each U.S. Marketing Plan shall define the goals and objectives for
Commercializing the Collaboration Products in the United States in the pertinent
Calendar Year consistent with the applicable U.S. Development Plan.

          5.1.2  Initial U.S. Marketing Plan for the POI Product. Within
                 -----------------------------------------------
one-hundred fifty (150) days after the Effective Date, the Joint Marketing
Committee shall prepare the U.S. Marketing Plan for the Commercialization
activities for the POI Product for the ** and the ** (**) Calendar Years after
the projected date of First Commercial Sale of the POI Product in the United
States in accordance Section 5.1.6, which such U.S. Marketing Plan shall include
the minimum Detail Requirements set forth on Schedule 5.7, the minimum Marketing
                                             ------------
Expenses set forth on Schedule 5.1.2 and the POI Contract Product Profile.
                      --------------

          5.1.3  Updated U.S. Marketing Plan for the POI Product. As early as
                 -----------------------------------------------
necessary in each Calendar Year beginning with the ** full Calendar Year after
the Effective Date, the Joint Marketing Committee shall amend and update the
U.S. Marketing Plan for the POI Product for the for the pre-launch period and
the following ** (**) Calendar Years for submission of such proposed U.S.
Marketing Plan to the Joint Steering Committee no later than ** of such year for
review and approval.

          5.1.4 U.S. Marketing Plan for OBD Chronic Product. Within ** (**)
                -------------------------------------------
days after filing the ** for the OBD Chronic Product, the Parties shall in good
faith review and mutually agree in good faith upon the content of a U.S.
Marketing Plan for the OBD Chronic Product. If no such mutual agreement is
reached, **. For purposes of this Section 5.1.4, in the situation where GSK is
not actively Developing or Commercializing the ** Product or ** Product in the
United States, "in good faith" means that Adolor has conducted and completed
such discussions with GSK on the content of such U.S. Marketing

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

Plan, with Adolor waving as its primary objective retention of the OBD Chronic
Product within the scope of this Agreement.

          5.1.5 Initial U.S. Marketing Plans for Other Collaboration Products.
                -------------------------------------------------------------
Commencing at least ** (**) full Calendar Years prior to the projected First
Commercial Sale of a Collaboration Product (other than the POI Product), the
Joint Marketing Committee will commence preparing an initial ** (**) year U.S.
Marketing Plan for such Collaboration Product for the pre-launch period and the
three (3) Calendar Years after the projected date of First Commercial Sale for
review and approval by the Joint Steering Committee. As early as necessary in
each Calendar Year thereafter, the Joint Marketing Committee shall amend and
update each U.S. Marketing Plan for such other Collaboration Products for the
for the pre-launch period and the following ** (**) Calendar Years for
submission of such proposed U.S. Marketing Plan to the Joint Steering Committee
no later than ** of such year for review and approval.

          5.1.6 Contents of Each U.S. Marketing Plan. Each U.S. Marketing Plan
                ------------------------------------
shall encompass at least ** (**) Calendar Years and shall contain at a
minimum:

                (a) Contract product profiles for the Collaboration Products,
provided that if the initial contract product profile for a Collaboration
Product set forth in a U.S. Marketing Plan is not substantiated by the final
FDA approved label for such Collaboration Product, then, subject to Article 16,
(i) Marketing Expenses will be adjusted accordingly, (ii) Detail Requirements
for Collaboration Products (other than the POI Product) will be adjusted
accordingly and (iii) Detail Requirements for the POI Product set forth on
Schedule 5.7 may be reallocated among the Target Audience (it being understood
------------
that such reallocation shall be by mutual agreement of the Parties and not
subject to the casting vote determination mechanism under Section 3.1.4(b));

                (b) Market research and strategy, including market size,
dynamics, growth, customer segmentation, competitive analysis and Collaboration
Product positioning;

                (c) Annual sales forecasts;

                (d) Advertising and promotion programs and strategies, including
sales literature, promotional premiums, media plans, symposia and speaker
programs;

                (e) Sales plans and activity, including sales force training,
projected Detailing in excess of the minimum Detail Requirements, where
applicable, and for each Party, development of appropriate sales training
materials, and strategy and budget for Samples;

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

                (f) Phase IV Studies to be conducted for use in the United
States, which studies shall be included in the then-current U.S. Marketing Plan
subject to Section 5.2.1; and

                (g) Identification of the total minimum Details required to
support the Collaboration Product (other than the POI Product) during such **
(**) Calendar Years including, where applicable in relation to any GI Product, a
firm indication of the number of Sales Representatives and Details to be
provided by Adolor in such period.

          5.1.7 Budget for Marketing Expenses. In addition to the items
                -----------------------------
enumerated in Section 5.1.6, each U.S. Marketing Plan shall set forth the total
budget for Marketing Expenses for such Collaboration Product. Such Marketing
Expense budget shall be sufficient to fund all necessary pre-launch, launch and
related activities necessary to optimize Commercialization of each Collaboration
Product. Notwithstanding the foregoing, unless otherwise agreed to by the
Parties, the total budget for the Marketing Expenses in a Calendar Year for an
Adolor Product or a GI Product for which Adolor is receiving a portion of the GI
Product Marketing Contribution shall not exceed ** percent (**%) of the budget
set forth in the most recently approved U.S. Marketing Plan for such
Collaboration Product. In the event that Marketing Expenses incurred by a Party
exceed the budgeted Marketing Expenses, the Party incurring such excess
Marketing Expenses shall be solely responsible for such expenses unless
otherwise mutually agreed in writing by the Parties.

     5.2  Marketing Funding.
          -----------------

          5.2.1 Adolor Products in the United States. Subject to reconciliation
                ------------------------------------
as provided in Section 6.7.5, on an Adolor Product-by-Adolor Product basis,
Adolor shall be responsible and pay for ** percent (**%) and GSK shall be
responsible and pay for ** percent (**%) of the Marketing Expenses for each
Adolor Product for Commercialization in the United States incurred from **
through the First Commercial Sale for such Adolor Product. Thereafter, Marketing
Expenses for each Adolor Product shall be shared in accordance with the sharing
of the Adolor Product Marketing Contribution for such Adolor Product as adjusted
pursuant to Section 6.3.4. Notwithstanding the foregoing, if a ** Study for an
Adolor Product is not commenced earlier than ** (**) years prior to the
expiration of the Adolor Product Promotion Term and such ** Study has no
applicability to a Collaboration Product in any Country in the ROW, Adolor shall
be responsible and pay for ** (**%) of any such ** Study.

          5.2.2 OBD Chronic Product in the United States. Subject to
                ----------------------------------------
reconciliation as provided in Section 6.7.5, Adolor shall be responsible and pay
for ** percent (**%) and GSK shall be responsible and pay for ** percent (**%)
of the Marketing Expenses in connection with the OBD Chronic Product for
Commercialization in the United States incurred from the Effective Date through

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

the First Commercial Sale for such OBD Chronic Product. Thereafter, Marketing
Expenses for the OBD Chronic Product shall be shared in accordance with the
sharing of the GI Product Marketing Contribution for such OBD Chronic Product as
adjusted pursuant to Section 6.3.4. Notwithstanding the foregoing, upon notice
by Adolor to GSK of a Royalty Conversion Election, GSK shall be solely
responsible and pay for all Marketing Expenses relating to periods after such
notice for the OBD Chronic Product for which the Royalty Conversion Election was
made.

          5.2.3 Other GI Products in the United States. Provided that Adolor
                --------------------------------------
elects to fund Development Expenses for a GI Product (other than the OBD Chronic
Product) pursuant to Section 4.6.5 and subject to reconciliation as provided in
Section 6.7.5, Adolor shall, from and after the date of such election, be
responsible and pay for ** percent (**%) and GSK shall be responsible
and pay for ** percent (**%) of the Marketing Expenses for such GI Product
(other than the OBD Chronic Product) in the United States until the First
Commercial Sale occurs for such GI Product. Thereafter, Marketing Expenses for a
GI Product (other than the OBD Chronic Product) shall be shared in accordance
with the sharing of the GI Product Marketing Contribution for such GI Product
(other than the OBD Chronic Product) as adjusted pursuant to Section 6.3.4.
Notwithstanding the foregoing, upon notice by Adolor to GSK of a Royalty
Conversion Election, GSK shall be solely responsible and pay for all Marketing
Expenses relating to periods after such notice for such GI Product for which the
Royalty Conversion Election was made.

          5.2.4 Marketing Expenses Incurred for the POI Product in the United
                -------------------------------------------------------------
States. Unless otherwise agreed to by the Joint Marketing Committee, all
------
Marketing Expenses for the POI Product shall be incurred by Adolor, subject to
reimbursement as provided for herein.

     5.3  Implementation of U.S. Marketing Plans. In implementing a U.S.
          --------------------------------------
Marketing Plan, each Party will develop and maintain appropriate liaison with
the Joint Marketing Committee to resolve any questions regarding such
implementation and to communicate to the Joint Marketing Committee timely
suggestions for improving the U.S. Marketing Plan. In connection with the
preparation and implementation of the U.S. Marketing Plan, Adolor and GSK will
make available to the Joint Marketing Committee marketing intelligence and
market research information then in their possession pertaining to the
Collaboration Products, the usage of the Collaboration Products and market
trends.

     5.4  Obligations for Commercialization.
          ---------------------------------

          5.4.1 General. The Parties shall use Commercially Reasonable Efforts
                -------
to Commercialize the Collaboration Products.

          5.4.2 GSK's Obligations. In furtherance of the foregoing, and subject
                -----------------
to GSK's termination rights pursuant to Article 16 (including those safety
related

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

termination rights pursuant to Section 16.4), GSK may not, either individually
or as a member of the Joint Steering Committee:

     **

     5.5  Commercialization Responsibilities.
          ----------------------------------

          5.5.1 Adolor Responsibilities.
                -----------------------

                (a) Adolor shall have the sole right and responsibility to
record and collect payment for sales of Adolor Products throughout the United
States.

                (b) Adolor shall use its Commercially Reasonable Efforts to
employ an appropriate management infrastructure to supervise the Sales
Representatives required to oversee Adolor's obligations to perform Detail
Requirements and marketing staff of sufficient size to establish, maintain and
implement the U.S. Marketing Plan for the Adolor Products.

                (c) In the event Adolor has not made a Royalty Conversion
Election for the OBD Chronic Product or another GI Product where Adolor has
elected to fund Development Expenses under Section 4.6.5, Adolor, **, may engage
Adolor Sales Representatives to Detail the relevant GI Product. In such event,
Adolor and GSK shall negotiate in good faith the minimum number of Details to be
conducted by the Parties to be included in the relevant U.S. Marketing Plan;
provided, however, in the event that Adolor elects to Detail such a GI Product,
Adolor must perform at least, and GSK shall not require Adolor to perform more
than, ** percent (**%) of the total Detail Requirements for such GI Product.

          5.5.2 GSK Responsibilities.
                --------------------

                (a) GSK shall have the sole right and responsibility to record
and collect payment for sales of GI Products throughout the United States.

                (b) GSK will be responsible for storage, order receipt, order
fulfillment, shipping and invoicing of Collaboration Products. In the case of
Adolor Products in the United States, invoices shall be for the account of
Adolor using an acceptable Adolor invoicing form and Adolor letterhead. The
Joint Marketing Committee shall establish mechanisms for real-time data

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the Commission. Confidential treatment has been requested with respect to the
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<PAGE>

exchange, invoicing schedules, credit control and other necessary standard
operating procedures relating to the invoicing for the account of Adolor.

                (c) In addition to the Detailing Requirements, GSK, at its sole
expense, commencing ** (**) months after the NDA Acceptance, and on an annual
basis for the period of the Adolor Product Promotion Term, shall provide, at a
minimum, the marketing and sales support for the POI Product as set forth on
Schedule 5.5.2.
--------------

                (d) GSK shall have the sole right and responsibility to
distribute, sell, record sales and collect payments for Collaboration Products
in the ROW during the ROW Term.

                (e) GSK shall have sole responsibility for establishing and
modifying the terms and conditions with respect to the sale of Collaboration
Products in the ROW, including, without limitation, the price or prices at which
the Collaboration Products in the ROW will be sold, any discount applicable to
payments or receivables, and similar matters.

                (f) Within ** (**) days after ** for the POI Product, GSK will
be responsible, at the direction of the Joint Marketing Committee, for
developing and implementing the healthcare insurance company and third party
payor reimbursement strategy for the Collaboration Products; provided, however,
that within ** (**) days after the ** anniversary of the First Commercial Sale
of the POI Product and subject to the approval of the Joint Marketing Committee,
Adolor may assume responsibility for such activities for any or all of the
Adolor Products; provided further that such assumption of responsibilities by
Adolor will not have a material adverse effect on the sales in the United States
of the POI Product.

                  5.5.3  Conditions for Sales of Collaboration Products in the
                         -----------------------------------------------------
United States. The Joint Marketing Committee shall establish and modify
-------------
conditions of sale of Collaboration Products to Third Parties in the United
States, including, without limitation, the price or prices at which the
Collaboration Products in the United States will be sold, any discount
applicable to payments or receivables, and similar matters.

             5.6  Detailing Efforts. The Parties shall market, Detail and
                  -----------------
Co-Promote the Collaboration Products in the United States in accordance with
the terms of this Agreement and the relevant U.S. Marketing Plan. No Party shall
be required to undertake any activity under this Agreement which it believes, in
good faith, would violate any Laws. GSK shall use Commercially Reasonable
Efforts to perform its annual Detail Requirements ** in each Calendar Quarter.
** Commercially Reasonable Efforts **. In any Calendar Year, no more than ** of
all Detail Requirements of a

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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Party for a GI Product in the United States, where Adolor has elected to fund
Development Expenses under Section 4.6.5 and has not made a Royalty Conversion
Election, shall be made by Specialist Sales Representatives.

             5.7  Detailing and Marketing Requirements. The Joint Marketing
                  ------------------------------------
Committee shall determine the targeted number of total Details and Primary
Details to be performed by each Party in the United States during each Calendar
Year and the Target Audience for such Details (the "Detail Requirements");
                                                    -------------------
provided, however,**. Unless otherwise agreed to by the Parties, a Party shall
not be required,**. Further, **. The Joint Marketing Committee shall allocate
**. No Party with respect to **

             5.8  Sales Force Incentive Compensation for POI Products. Each
                  ---------------------------------------------------
Party shall offer incentive compensation to its Sales Representatives with
respect to the sale of the POI Product in the United States for each Calendar
Year during the Adolor Product Promotion Term. Such incentive schemes shall be
adopted by each Party in a manner consistent with the way other incentive
schemes are adopted within their respective organizations; provided, however,
that **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

**. Each Party shall notify the other Party, prior to the First Commercial Sale
and prior to the commencement of each Calendar Year thereafter, of the
structure, formula and relative competitiveness of such arrangement (having
regard to other such arrangements adopted by GSK, Adolor, or other companies in
the pharmaceutical industry for a company similar in size and scope to such
Party).

             5.9  Detailing Reports.
                  -----------------

                  5.9.1  Reports. Within thirty (30) days following the end of
                         -------
each Calendar Quarter, each Party shall provide the Joint Marketing Committee
with a report setting forth, in such detail and form as the Joint Marketing
Committee shall require (the "Internal Detailing Report"), based upon each
                              -------------------------
Party's internal Call reporting and Detailing auditing system, the total number
of Details, Major Details and Secondary Details actually performed by such
Party, in the United States, segmented by physician specialty of the Target
Audience during the immediately preceding Calendar Quarter.

                  5.9.2  Records and Audits Pertaining to Details. At any time
                         ----------------------------------------
during the Term of this Agreement, but not more than twice every Calendar Year,
each Party agrees to make available to the auditing Party, upon reasonable
advance notice, such books and records necessary to verify the accuracy of such
Internal Detailing Report with respect to any Calendar Quarter ending not more
than twelve (12) Calendar Quarters prior to the date of such request. Unless the
auditing Party has notified the other Party of an issue relating to verifying an
Internal Detailing Report for a particular Calendar Quarter, such other Party
shall be released from any liability or accountability to the auditing Party for
Detailing in any Calendar Quarter ending more than twelve (12) Calendar Quarters
prior to the initiation of such verification process by the auditing Party. In
the event of an unresolved dispute regarding the number of Details actually
performed by a Party based on such Party's internal Call reporting and Detail
auditing system, the Parties hereby agree that such Party's internal Call
reporting and Detail auditing system may be correlated (on a trend basis only)
with the Dispute Detailing Audit Data. Such correlation may be used by the
auditing Party in any court or arbitration proceeding with respect to any
dispute regarding Detailing under this Agreement.

            5.10  Training.
                  --------

                  5.10.1  Training Plans. The Joint Marketing Committee shall
                          --------------
develop training plans at least ** (**) days ** a Collaboration Product. GSK and
Adolor shall, each at its own expense, comply with the training plan contained
in any U.S. Marketing Plan which is otherwise consistent with provisions of this
Agreement. Each Party will be responsible for

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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supervising, training and maintaining its Sales Representatives as may be
required to Detail the Collaboration Products as provided herein or in the
applicable U.S. Marketing Plan, such training to include a reasonable
proficiency examination relevant to the Collaboration Products given at least
annually for all Sales Representatives who will be engaged in Detailing, at such
Party's own cost and expense. Adolor shall have the right to participate in the
training programs of GSK, and GSK shall have the right to participate in the
training programs of Adolor, for the purpose of ensuring overall consistency in
the training programs for the Collaboration Products.

                  5.10.2  Assistance. During the United States Term, each Party
                          ----------
shall make available to the other for use in connection with Co-Promoting the
Collaboration Products in the United States, to the extent reasonable,
assistance and services relating to such Co-Promotion, including, but not
limited to, providing the other Party, free of charge and in a timely manner,
with a master copy of such training materials relating to Collaboration Products
as such Party has used and/or intends to use in connection with the training of
its Sales Representatives, including but not limited to learning units and any
other printed, audio and video training materials. To the extent the other Party
wishes to use such training materials in the training of its own Sales
Representatives, it will be responsible for reproducing such training materials.

                  5.10.3  Training of Sales Representatives. All Sales
                          ---------------------------------
Representatives of a Party have received, or will receive in a timely manner,
appropriate training on proper marketing and sales techniques to be used in
promoting pharmaceutical products in accordance with applicable Laws.

                  5.10.4  Joint Marketing and Sales Meetings. The Parties shall
                          ----------------------------------
plan and implement periodic joint sales and marketing meeting, including a
national launch meeting, for each Adolor Product, and the OBD Chronic Product
and each other GI Product where Adolor has elected to fund Development Expenses
under Section 4.6.5 and where Adolor has not made a Royalty Conversion Election,
in the United States. Costs and expenses attributable to individual attendees of
each Party, such as lodging and transportation, shall be borne by such Party and
shall not be deemed a Marketing Expense. All other expenses associated with such
meetings shall be deemed **.

           5.11   Commercialization in the ROW.
                  ----------------------------

                  5.11.1  GSK Responsibility. GSK shall have sole responsibility
                          ------------------
for Commercialization of Collaboration Products for distribution and sale in the
ROW. **, GSK shall bear all costs and expenses associated with the
Commercialization of Collaboration Products for sale or distribution in the ROW.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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                  5.11.2  Coordination; Semi-Annual Reports.
                          ---------------------------------

                          (a)  GSK shall coordinate through the Joint Steering
Committee the Commercialization of Collaboration Products in the ROW with the
Commercialization of Collaboration Products in the United States with the
objective of coordination of global product positioning and sharing of best
practices and strategies.

                          (b)  GSK shall provide the Joint Steering Committee
reports semi-annually. Such reports shall set forth in summary form the results
of GSK's Commercialization activities performed during such semi-annual period.

                          (c)  No later than ** of each Calendar Year, GSK shall
provide to Adolor in writing a good faith estimate of the projected Net Sales by
Calendar Quarter on a Country-by-Country basis for the Major Market Countries,
and a summary for the remainder of the ROW, of each Collaboration Product for at
least ** (**) full Calendar Years after the anticipated First Commercial Sale of
such Collaboration Product (the "ROW Net Sales Forecast").

GSK shall update each ROW Net Sales Forecast on a semi-annual basis. For the POI
Product in the ROW, the first ROW Net Sales Forecast shall be furnished to
Adolor within one hundred twenty (120) days after the Effective Date. For each
Collaboration Product (other than the POI Product) in the ROW, the first ROW Net
Sales Forecast shall be furnished to Adolor at least ** (**) full Calendar Years
prior to the projected First Commercial Sale in the ROW of such Collaboration
Product.

                  5.11.3  Decisions with Respect to Collaboration Products in
                          ---------------------------------------------------
the ROW. GSK shall have the sole discretion with respect to Commercialization
-------
decisions for Collaboration Products in the ROW subject to Section 3.1.4(b) and
provided that GSK takes into account on a global basis the goal of realizing the
best overall commercial potential of the Products.

                  5.11.4  Exports to the United States. The Parties shall use
                          ----------------------------
Commercially Reasonable Efforts to prevent the Collaboration Products
distributed for sale in a particular Country other than the United States from
being exported to the United States for sale.

                                   ARTICLE 6
                              FINANCIAL PROVISIONS

            6.1   Upfront Payment. In partial consideration for the acquisition
                  ---------------
of license rights under the Adolor Patents and the Adolor Know-How by GSK under
this Agreement, GSK shall, within ** (**) Business Days after the Effective
Date, pay to Adolor a non-creditable, non-refundable amount of fifty million
United States Dollars (US $50,000,000) and Adolor shall issue GSK on the
Effective Date the invoice therefor attached hereto as Schedule 6.1.
                                                       ------------

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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            6.2   Milestone Payments.
                  ------------------

                  6.2.1   In further consideration of the acquisition of license
rights under Adolor Patents and the Adolor Know-How by GSK under this Agreement,
GSK shall also pay to Adolor the payments set forth in Schedule 6.2 for each
                                                       ------------
such Development milestone referred to therein (each, a "Development
                                                         -----------
Milestone"); provided always that each such payment shall be made only one time
---------
for each Collaboration Product in accordance with Schedule 6.2 regardless of how
                                                  ------------
many times such Development Milestones are achieved for such Collaboration
Product, and no payment shall be owed for a Development Milestone which is not
reached (except that, upon achievement of a Development Milestone for a
particular Collaboration Product, any previous Development Milestone for that
Collaboration Product for which payment was not made shall be deemed achieved
and payment therefor shall be made); provided further that, in the event that
more than one Development Milestone is achieved with respect to the same
Collaboration Product at one time or from time to time, then all applicable
payments under Schedule 6.2 shall be made to Adolor. By way of example, if the
               ------------
Constipation Product and the IBS Product are approved in the same Marketing
Authorization Approval, then, in addition to the relevant milestone for the
Constipation Product, the relevant milestone for the IBS Product shall be paid
simultaneously.

                  6.2.2  In the event a Party achieves a Development Milestone,
such Party shall promptly, but in no event more than five (5) days after the
achievement of each such Development Milestone, notify the other Party in
writing of the achievement of same. For all Development Milestones achieved, GSK
shall promptly, but in no event more than thirty (30) days after the achievement
of each such Development Milestone, remit payment to Adolor for such Development
Milestone.

            6.3   Marketing Contribution for Collaboration Products.
                  -------------------------------------------------

                  6.3.1  Share of Adolor Product Marketing Contribution. During
                         ----------------------------------------------
the period beginning with the First Commercial Sale of each Adolor Product and
ending on the last day of the Calendar Quarter in which the ** anniversary of
such First Commercial Sale occurs (the "Initial ** Year Period"), Adolor shall
                                        ----------------------
receive ** percent (**%) and GSK shall receive ** percent (**%) of the Adolor
Product Marketing Contribution of such Adolor Product, subject to adjustment as
set forth in Section 6.3.4 and reconciliation as set forth in Section 6.7.5.
After the Initial ** Year Period, each Party shall receive ** percent (**%) of
the Adolor Product Marketing Contribution for such Adolor Product, subject to
adjustment as set forth in Section 6.3.4 and reconciliation as set forth in
Section 6.7.5.

                  6.3.2  Share of GI Product Marketing Contribution. For the OBD
                         ------------------------------------------
Chronic Product and for any other GI Product where Adolor has elected to fund
Development Expenses pursuant to Section 4.6.5, and provided further that Adolor
has not made a Royalty Conversion Election as provided in Section 6.3.5, Adolor
shall

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

receive ** percent (**%) and GSK shall receive ** percent (**%) of the GI
Product Marketing Contribution for a GI Product, subject to adjustment as set
forth in Section 6.3.4 and reconciliation as set forth in Section 6.7.5.

                  6.3.3  Compensation for Distribution Services. GSK shall
                         --------------------------------------
receive ** percent (**%) of Net Sales in the United States as the sole
compensation to GSK for the services to be provided in the United States
pursuant to Section 5.5.2(b) (the "Distribution Services Fee") for Adolor
                                   -------------------------
Products and for GI Products where Adolor funds Development of such GI Product
and has not made a Royalty Conversion Election, which amount shall be paid in
accordance with this Article 6. Within one hundred eighty (180) days after the
Effective Date, the Parties shall negotiate in good faith a distribution
services agreement with respect to the foregoing.

           6.3.4 Adjustment of Marketing Contribution. On a Collaboration
                 ------------------------------------
Product-by-Collaboration Product basis, in the event that a Party only performs
between ** percent (**%) and ** percent (**%) of its Detail Requirements
(measured for both its total Details and Primary Details) in a Calendar Year
(the "Defaulting Party"), then the Defaulting Party's share of the Adolor
      ----------------
Product Marketing Contribution or GI Product Marketing Contribution, as
applicable, for such Calendar Year shall be reduced by ** percentage (**%)
points and the other Party's share of the Adolor Product Marketing Contribution
or the GI Product Marketing Contribution, as applicable, for such Calendar Year
shall be correspondingly increased. In the event the Defaulting Party performs
less than ** percent (**%) of its Detail Requirements (measured for both its
total Details and Primary Details) for a Collaboration Product in such Calendar
Year, then, in addition to the ** percentage (**%) point reduction, the
Defaulting Party's share of the Adolor Product Marketing Contribution or GI
Product Marketing Contribution, as applicable, for such Calendar Year shall also
be reduced ** percentage (**%) ** for each ** percentage (**%) ** that the
Defaulting Party's actual number of Details is less than ** percent (**%) of the
Defaulting Party's Detail Requirements (measured for both its total Details and
Primary Details) and the other Party's share of the Adolor Product Marketing
Contribution or the GI Product Marketing Contribution, as applicable, for such
Calendar Year shall be correspondingly increased. If a Party is a Defaulting
Party for a Collaboration Product for ** (**) **, then the Adolor Product
Marketing Contribution or the GI Product Marketing Contribution, as applicable,
shall be permanently reduced and correspondingly increased for the other Party,
by an amount equal to the average of the adjustments made for the ** (**) **. In
the event that a Party fails to perform at least ** percent (**%) of its Detail
Requirements (measured for both its total Details and Primary Details) for a
Collaboration Product in a Calendar Year, that Party shall be deemed to have
materially breached this Agreement and such breach shall be deemed incurable.
For purposes of this Section, the determination as to whether GSK has met its
minimum Detail Requirements shall be made with respect to both its Detail
Requirements to ** as a Target Audience and to GSK's total

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

Detail Requirement. The provisions of this Section 6.3.4 shall apply even if
both Parties are a Defaulting Party.

           6.3.5 Conversion to Royalty. On a GI Product-by-GI Product basis,
                 ---------------------
within ** (**) days ** for such GI Product, and within ** (**) months after each
** (**) year anniversary thereafter, Adolor shall have the right to convert its
right to receive a percentage of the GI Product Marketing Contribution to a
royalty, as set forth in Section 6.4.2 (the "Royalty Conversion Election"). The
                                             ---------------------------
Royalty Conversion Election shall be made in writing, and shall be irrevocable
once made. Upon making the Royalty Conversion Election, Adolor shall have no
further obligation to fund or otherwise be responsible for any expenses relating
to such GI Product for any time periods following the delivery of the Royalty
Conversion Election.

     6.4   Payment of Royalties on Net Sales in the ROW.
           --------------------------------------------

           6.4.1 Within thirty (30) days after the end of each Calendar Quarter,
GSK shall pay Adolor royalty payments based on Net Sales in such Calendar
Quarter in the ROW during the ROW Term as follows: (a) ** percent (**%) for GI
Products; and (b) ** percent (**%) for Adolor Products. The royalty payments
made under this Section 6.4.1 shall be based on actual Net Sales for the first
two (2) months of a Calendar Quarter and an estimate for the third month of the
Calendar Quarter based upon projected Net Sales. Within sixty (60) days after
the end of each Calendar Quarter, GSK shall calculate the actual amount of Net
Sales for the third month of such Calendar Quarter and either credit or debit
the difference between such actual and projected amount on the succeeding
Calendar Quarter's royalty payment to Adolor.

           6.4.2 For Collaboration Products in the ROW where there is Generic
Competition and where the ROW Term has not expired pursuant to Section 1.125(a)
or 1.125(b), on a Country-by-Country and Collaboration Product-by-Collaboration
Product basis, royalty rates shall be reduced by ** percent **.

       6.5 Payment of Royalties on Net Sales of GI Products in the United
           --------------------------------------------------------------
States. Within thirty (30) days after the end of each Calendar Quarter, GSK
------
shall pay Adolor royalty payments based on Net Sales in such Calendar Quarter in
the United States during the GI Product Promotion Term as follows: (a) ** (** %)
for GI Products where Adolor has not elected to fund Development Expenses for
such GI Product; and (b) ** percent (** %) for the OBD Chronic Product, and
other GI Products where Adolor has elected to fund Development Expenses for such
GI Product and subsequently made a Royalty Conversion Election; provided that if
the First Commercial Sale in the United States for the OBD Chronic Product has
not occurred prior to the First Commercial Sale in the United States of either
the ** Product or the ** Product, then the royalty rate on such ** Product or **
Product shall be ** (**%) regardless of whether Adolor has funded Development
Expenses for such GI Product; provided further that if the OBD Chronic Product
is subsequently launched and Adolor has not elected to fund Development Expenses
for the ** Product and **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

Product the royalty rate on such ** Product or ** Product shall thereafter be
reduced to ** (**%). The royalty payments made under this Section 6.5 shall be
based on actual Net Sales for the first two (2) months of a Calendar Quarter and
an estimate for the third month of the Calendar Quarter based upon projected Net
Sales. Within sixty (60) days after the end of each Calendar Quarter, GSK shall
calculate the actual amount of Net Sales for the third month of such Calendar
Quarter and either credit or debit the difference between such actual and
projected amount on the succeeding Calendar Quarter's royalty payment to Adolor.

       6.6 Royalty Responsibilities; Net Sales Reports.
           -------------------------------------------

           6.6.1 Payments to Third Parties.
                 -------------------------

                 (a) Adolor shall pay any amounts owed Lilly and Shire as a
result of the use of the Adolor Patents or Adolor Know-How with respect to sales
of Collaboration Products. Any royalties paid to Lilly and Shire pursuant to
this Section 6.6.1(a) shall be subject to reconciliation pursuant to Section
6.7.5.

                 (b) GSK shall pay any amounts owed to a Third Party, other than
to Lilly and Shire, as a result of the use of the Adolor Patents or Adolor
Know-How (i) with respect to sales of GI Product in the United States on which
Adolor is receiving a royalty and Collaboration Products in the ROW and shall
deduct such amounts from Net Sales in such Country prior to calculating
royalties owed to Adolor and (ii) with respect to sales of GI Products in the
United States where Adolor has elected to fund Development Expenses under
Section 4.6.5, in each case where Adolor has not made a Royalty Conversion
Election, and subject to reconciliation pursuant to Section 6.7.5.

                 (c) The Parties shall each be responsible for ** percent
(**%) of royalty amounts, if any, owed to a Third Party relating to ** (except
for any royalty amounts pursuant to subsection (a) above) subject to
reconciliation pursuant to Section 6.7.5.

                 (d) GSK shall pay any amounts owed to a Third Party other than
as set forth in Section 6.6.1(a), 6.6.1(b) or 6.6.1(c) (i) with respect to sales
of GI Products in the United States for which Adolor is receiving a royalty and
Collaboration Products in the ROW and shall not deduct such amounts from Net
Sales prior to calculating royalties owed to Adolor and (ii) with respect to
sales of the OBD Chronic Product in the United States and other GI Products in
the United States where Adolor has elected to fund Development Expenses under
Section 4.6.5, in each case where Adolor has not made a Royalty Conversion
Election, and subject to reconciliation pursuant to Section 6.7.5.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

          6.6.2 Net Sales Report. Within thirty (30) days after the end of each
                 ----------------
Calendar Quarter, GSK shall submit to Adolor a written report setting forth Net
Sales in the ROW and the United States (but only if Adolor is receiving royalty
payments based on sales in the United States) on a Country-by-Country and
Collaboration Product-by-Collaboration Product basis during such Calendar
Quarter, total royalty payments due Adolor, relevant market share data
supporting the presence of Generic Competition, if any, and any payments made to
any Third Party pursuant to Section 6.6.1 (each a "Net Sales Report").
                                                   ----------------

           6.6.3 Basis for Royalty Payment. The Parties acknowledge that the
                 -------------------------
royalty payments provided for in Sections 6.4 and 6.5 are intended to provide
appropriate economic benefits to Adolor in recognition for **.

     6.7   Reports.
           -------

           6.7.1 Estimate Reports. Within ten (10) days after the end of each
                 ----------------
Calendar Quarter, GSK shall prepare and deliver to Adolor a report for internal
accounting purposes setting forth GSK's good faith estimate of Net Sales of GI
Products In the United States and Collaboration Products in the ROW and Adolor's
share of the GI Product Marketing Contribution. Within ten (10) days after the
end of each Calendar Quarter, Adolor shall prepare and deliver to GSK a report
for internal accounting purposes setting forth Adolor's good faith estimate of
Net Sales of Adolor Products and GSK's share of the Adolor Product Marketing
Contribution.

           6.7.2 GSK Report. Within forty-five (45) days after the end of each
                 ----------
Calendar Quarter, on a Collaboration Product-by-Collaboration Product basis in
the United States, GSK shall submit to Adolor a written report (each, a "GSK
                                                                         ---
Report") setting forth in reasonable detail the following items during such
------
Calendar Quarter:

                 (a) Development Expenses incurred by GSK for each: (i) Adolor
Product; and (ii) GI Product for which Adolor will receive a percentage of GI
Product Marketing Contribution;

                 (b) Marketing Expenses incurred by GSK for each: (i) Adolor
Product; and (ii) the OBD Chronic Product and each other GI Product for where
Adolor has elected to fund Development Expenses under Section 4.6.5, and where
Adolor has not made a Royalty Conversion Election;

                 (c) Cost of Goods for the OBD Chronic Product and each other GI
Product for where Adolor has elected to fund Development Expenses under Section
4.6.5, and where Adolor has not made a Royalty Conversion Election (except for
any ** under a supply agreement between the Parties);

                 (d) API Compound Carrying Cost;

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

                 (e) Royalties, if any, paid by GSK to Third Parties in
accordance with Section 6.6.1;

                 (f) Detail Costs for the OBD Chronic Product and each other GI
Product for where Adolor has elected to fund Development Expenses under Section
4.6.5, and where Adolor has not made a Royalty Conversion Election; and

                 (g) Net Sales of Collaboration Products in the United States
and the ROW.

           6.7.3 Adolor Report. Within forty-five (45) days after the end of
                 -------------
each Calendar Quarter, on a Collaboration Product-by-Collaboration Product basis
in the United States, Adolor shall submit to GSK a written report (each, an
"Adolor Report") setting forth in reasonable detail the following items during
 -------------
such Calendar Quarter:

                 (a) Development Expenses incurred by Adolor for each: (i)
Adolor Product; and (ii) the OBD Chronic Product and each other GI Product for
where Adolor has elected to fund Development Expenses under Section 4.6.5, and
where Adolor has not made a Royalty Conversion Election;

                 (b) Marketing Expenses incurred by Adolor for each: (i) Adolor
Product; and (ii) the OBD Chronic Product and each other GI Product for where
Adolor has elected to fund Development Expenses under Section 4.6.5, and where
Adolor has not made a Royalty Conversion Election;

                 (c) Cost of Goods for each Adolor Product in the United States
(except for any Cost of Goods separately reimbursed under a supply agreement
between the Parties);

                 (d) Royalties, if any, paid by Adolor to Third Parties in
accordance with Section 6.6.1;

                 (e) API Compound Carrying Cost;

                (f) Detail Costs for the OBD Chronic Product and each other GI
Product for where Adolor has elected to fund Development Expenses under Section
4.6.5, and where Adolor has not made a Royalty Conversion Election; and

                 (g) Net Sales of Adolor Product in the United States.

           6.7.4 Reimbursements. In conjunction with the reconciliation set
                 --------------
forth in Section 6.7.5:


                 (a) Adolor shall reimburse GSK: (i) ** percent (**%) of
Marketing Expenses, Cost of Goods (except for any Cost of Goods separately
reimbursed under a supply agreement between the Parties), Distribution Services
Fees and royalties to Third Parties, in each case paid or incurred by GSK with
respect to Adolor Products sold in the United States for which Adolor is
recording sales and collecting payments; and

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

(ii) API Compound Carrying Cost incurred by GSK for all Collaboration Products.

                 (b) GSK shall reimburse Adolor: (i) ** percent (**%)
of Marketing Expenses, Cost of Goods (except for any Cost of Goods separately
reimbursed under a supply agreement between the Parties) and royalties to Third
Parties, in each case paid or incurred by Adolor with respect to GI Products
sold in the United States for which GSK is recording sales and collecting
payments; (ii) API Compound Carrying Cost incurred by Adolor for all
Collaboration Products; and (iii) Detail Costs for the actual Details performed
by Adolor for the OBD Chronic Product and each other GI Product for where Adolor
has elected to fund Development Expenses under Section 4.6.5, and where Adolor
has not made a Royalty Conversion Election.

                 (c) The Parties shall determine the total Development Expenses
for the relevant reporting period and shall effect the reimbursement of the
Development Expenses as necessary consistent with each Party's share of such
Development Expenses pursuant to Section 4.6.

           6.7.5 Financial Reconciliation.
                 ------------------------

                 (a) Within sixty (60) days after the end of each Calendar
Quarter, commencing with first Calendar Quarter during which the Effective Date
occurs (which shall include all periods since January 1, 2002, Adolor shall,
using the GSK Report and the Adolor Report, prepare a reconciliation report for
Adolor Products in the United States (the "Adolor Reconciliation Report") which
                                           ----------------------------
shall show the Development Expenses either Party may owe the other, the
calculation of the Adolor Product Marketing Contribution, each Party's share of
the Adolor Product Marketing Contribution, the reimbursements owed to GSK
pursuant to Section 6.7.4(a), and the resulting net amount owed by Adolor to GSK
or by GSK to Adolor as the case may be, in each case for Adolor Products in the
United States. Within twenty (20) days after receipt by GSK of the Adolor
Reconciliation Report, GSK or Adolor, as the case may be, shall pay the net
amount shown therein to the other Party.

                 (b) Within sixty (60) days after the end of each Calendar
Quarter, commencing with the first Calendar Quarter following the Effective
Date, GSK shall, using the GSK Report and the Adolor Report, prepare a
reconciliation report for GI Products in the United States (the "GSK
                                                                 ---
Reconciliation Report") which shall show the Development Expenses either Party
---------------------
may owe the other, the calculation of the GI Product Marketing Contribution,
each Party's share of the GI Product Marketing Contribution, the reimbursements
owed to Adolor pursuant to Section 6.7.4(b) and the resulting net amount owed by
Adolor to GSK or by GSK to Adolor as the case may be, in each case for GI
Products in the United

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

States. Within twenty (20) days after receipt by Adolor of the GSK
Reconciliation Report, GSK or Adolor, as the case may be, shall pay the net
amount shown therein to the other Party.

     6.8  Payment Upon Expiration of the Adolor Product Promotion Term.
          ------------------------------------------------------------

          6.8.1 If the Adolor Product Promotion Term expires on the ** (**)
anniversary of the First Commercial Sale of the POI Product in the United
States, Adolor shall pay GSK an amount equal to the sum of: (i) ** which amount
shall be paid in four equal quarterly installments commencing in the first
Calendar Quarter following the expiration of the Adolor Product Promotion Term,
and (ii) ** which amount shall be paid in four equal quarterly installments
commencing with the fifth Calendar Quarter following expiration of the Adolor
Product Promotion Term.

          6.8.2 If the Adolor Product Promotion Term expires on the ** (**)
anniversary of the First Commercial Sale of the POI Product in the United
States, Adolor shall pay GSK an amount equal to ** which amount shall be paid
in four equal quarterly payments commencing with the first Calendar Quarter
following the expiration of the Adolor Product Promotion Term.

          6.8.3 No payment shall be made pursuant to this Section 6.8 if the
Adolor Product Promotion Term expires after the ** (**) anniversary of
the First Commercial Sale of the POI Product or is terminated prior to the
expiration of the Adolor Product Promotion Term.

     6.9  GAAP. All financial terms and standards defined or used in this
          ----
Agreement for sales or activities occurring in the United States shall be
governed by and determined in accordance with United States generally accepted
accounting principles, consistently applied. Except as otherwise set forth
herein, all financial terms and standards defined or used in this Agreement for
sales or activities occurring in the ROW shall be governed by and determined in
accordance with United Kingdom generally accepted accounting principles,
consistently applied.

     6.10 Currencies. Payments under this Agreement shall be made in United
          ----------
States Dollars. Revenues and expenses for each Country shall be converted into
United States Dollars using the applicable exchange rate for converting such
local currency to the United States Dollar in accordance with the exchange rates
used by GSK in producing its financial accounts at the time and detailed in its
annual report as agreed by its auditors.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

     6.11 Manner of Payments. All sums due to either Party under this Article 6
          ------------------
shall be payable in United States Dollars by bank wire transfer in immediately
available funds to such bank account(s) as each of GSK and Adolor shall
designate. GSK shall notify Adolor as to the date and amount of any such wire
transfer to Adolor at least two (2) Business Days prior to such transfer. Adolor
shall notify GSK as to the date and amount of any such wire transfer to GSK at
least two (2) Business Days prior to such transfer.

     6.12 Interest on Late Payments. If either Adolor or GSK shall fail to make
          -------------------------
a timely payment pursuant to this Article 6, any such payment that is not paid
on or before the date such payment is due under this Agreement shall bear
interest, to the extent permitted by applicable law, at the average one-month
London Inter-Bank Offering Rate (LIBOR) for the United States Dollar as reported
from time to time in The Wall Street Journal, effective for the first date on
which payment was delinquent and calculated on the number of days such payment
is overdue or, if such rate is not regularly published, as published in such
source as the Joint Steering Committee agrees.

     6.13 Tax Withholding. Any taxes, levies or other duties ("Taxes") paid or
          ---------------                                      -----
required to be withheld under the appropriate local tax laws by one of the
Parties ("Withholding Party") on account of monies payable to the other Party
          -----------------
under this Agreement shall be deducted from the amount of monies otherwise
payable to the other Party under this Agreement. The Withholding Party shall
secure and send to the other Party within a reasonable period of time proof of
any such Taxes paid or required to be withheld by Withholding Party for the
benefit of the other Party. The Parties shall cooperate reasonably with each
other to ensure that any amounts required to be withheld by either Party are
reduced in amount to the fullest extent permitted by Law. No deduction shall be
made, or a reduced amount shall be deducted, if the other Party furnishes a
document from the appropriate tax Governmental Authorities to the Withholding
Party certifying that the payments are exempt from Taxes or subject to reduced
tax rates, according to the applicable convention for the avoidance of double
taxation.

     6.14 Financial Records; Audits. Each Party shall keep, and shall cause its
          -------------------------
Affiliates and sublicensees to keep, such accurate and complete records of Net
Sales and its Marketing Expenses and Development Expenses as are necessary to
determine the amounts due to GSK and Adolor under this Agreement. Such records
shall be retained by each Party or any of its Affiliates or sublicensees (in
such capacity, the "Recording Party"). During normal business hours and with
                    ---------------
reasonable advance notice to the Recording Party, such records shall be made
available for inspection, review and audit, at the request and expense of the
other Party (the "Auditing Party"), by an independent certified public
                  --------------
accountant, or the local equivalent, appointed by such Auditing Party and
reasonably acceptable to the Recording Party for the sole purpose of verifying
the accuracy of the Recording Party's accounting reports and payments made or to
be made pursuant to this Agreement; provided, however that such audits may not
be performed by the Auditing Party more than once per Calendar Year and that
such Auditing Party shall not be permitted to audit the same period of time more
than once. Such accountants shall be instructed not to reveal to the Auditing
Party the details of its review, except for (i) such information as is required
to be disclosed under this Agreement and (ii) such information presented in a
summary fashion as is necessary to report the accountants' conclusions to

                                      -63-

<PAGE>

the Auditing Party, and all such information shall be deemed Confidential
Information of the Recording Party; provided, however, that in any event such
information may be presented to the Auditing Party in a summary fashion as is
necessary to report the accountants' conclusions. All costs and expenses
incurred in connection with performing any such audit shall be paid by the
Auditing Party unless the audit discloses at least a ** percent (**%) shortfall,
in which case the Recording Party will bear the full cost of the audit for such
Calendar Year. The Auditing Party will be entitled to recover any shortfall in
payments due to it as determined by such audit, plus interest thereon calculated
in accordance with Section 6.12, or alternatively shall have the right to offset
and deduct any such shortfall in payments due to it against payments the
Auditing Party is otherwise required to make to the Reporting Party under this
Agreement. The documents from which were calculated the sums due under this
Article 6 shall be retained by the relevant Party during the United States Term
or the ROW Term, as applicable.

                                    ARTICLE 7
                        PROMOTIONAL MATERIALS AND SAMPLES

     7.1  Promotional Materials.
          ---------------------

           7.1.1 Creation of United States Promotional Materials. Subject to the
                 -----------------------------------------------
terms of Section 7.1.2 and applicable Law, for Adolor Products during the Adolor
Product Promotion Term and for GI Products during the GI Product Promotion Term,
in accordance with the direction of the Joint Marketing Committee, the Parties
will jointly, through consultation and with the assistance of each other, create
and develop Promotional Materials for the United States. GSK may use the
Promotional Materials for the United States as the promotional materials in the
ROW or GSK shall, subject to Sections 3.1.4(b) and 3.3.2, create and develop
promotional materials suitable for use in the ROW.

           7.1.2 Adolor Ownership of United States Promotional Materials.
                 -------------------------------------------------------
Subject to the terms of this Section 7.1, Adolor shall own all right, title and
interest in and to any Promotional Materials relating to the Adolor Products in
the United States, including without limitation applicable copyrights and
trademarks, and GSK hereby assigns all its right, title and interest to such
Promotional Materials to Adolor and agrees to execute all documents and take all
actions as are reasonably requested by Adolor to vest title to such Promotional
Materials in Adolor in the United States.

           7.1.3 GSK Ownership of United States and ROW Promotional Materials.
                 ------------------------------------------------------------
Subject to the terms of this Section 7.1, GSK shall own all right, title and
interest in and to any Promotional Materials relating to GI Products in the
United States and to any promotional materials relating to Collaboration
Products in the ROW, including without limitation applicable copyrights and
trademarks, and Adolor hereby assigns all its right, title and interest to such
materials to GSK and agrees to execute all documents and take all actions as are
reasonably requested by GSK to vest title to such materials in GSK.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

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<PAGE>

           7.1.4 Retention of Rights. GSK and Adolor, or their respective
                 -------------------
Affiliates, shall retain all rights, including without limitation all copyrights
and trademarks, to all of their respective existing programs and materials in
all formats (print, video, audio, digital, computer, etc.) regarding sales
training, patient education and disease management programs owned by each at the
time such materials are shared with the other Party, as well as any
modifications of such programs each may develop in the future which are not
specific to a Collaboration Product. GSK and Adolor shall, from time to time,
each notify the other as to the identity of such proprietary programs that may
be relevant for purposes of this Agreement. In the event that Adolor desires
after the expiration or termination of this Agreement, to use any GSK program
which has been specifically adapted for, or directed to, a Collaboration Product
under this Agreement, the Parties shall negotiate in good faith to conclude, if
possible, an appropriate agreement under which Adolor would be permitted to
engage in such continued use (including without limitation the amount of
compensation to be paid to GSK for such use). In addition, all such new programs
hereafter jointly developed by GSK and Adolor pursuant to this Agreement shall
be jointly owned by GSK and Adolor, and each Party shall have the right to use
such jointly developed programs free of charge after the Term, subject to the
remaining obligations imposed on the Parties under this Agreement.

           7.1.5 Review of Promotional Materials in the United States. The
                 ----------------------------------------------------
relevant legal or regulatory personnel of each Party shall have the opportunity
to review and comment on all Promotional Materials in the United States prior to
use and such comments shall be considered by Joint Marketing Committee in the
preparation of such Promotional Materials.

           7.1.6 Use of Promotional Materials in the United States. Except as
                 -------------------------------------------------
provided in Section 7.1.1, neither Party shall produce (other than as concepts
for consideration by the other Party), distribute or otherwise use any
Promotional Materials in the United States in connection with Co-Promoting the
Collaboration Products unless and until such Promotional Materials have been
approved in accordance with this Agreement.

           7.1.7 Markings of Promotional Materials in the ROW. To the extent
                 --------------------------------------------
required by applicable Law, and further to the extent reasonably practicable,
all promotional materials used in the ROW will indicate that the Collaboration
Products are sold under license from Adolor.

           7.1.8 Discontinued Use.
                 ----------------

                 (a) Promptly after the termination or expiration of the Adolor
Product Promotion Term, GSK shall (a) immediately cease use of all Promotional
Materials relating to the Adolor Products in the United States, (b) return, or
otherwise dispose of in accordance with instructions from Adolor, all
Promotional Materials relating to the Adolor Products in the United States that
remain in GSK's or its Affiliates' possession or control, and (c) upon written
request by Adolor provide Adolor with a certified statement that

                                    -65-

<PAGE>

all such remaining Promotional Materials relating to the Adolor Products in the
United States have been returned or otherwise properly disposed of, and that GSK
is no longer in possession or control of any such Promotional Materials relating
to the Adolor Products in the United States.

                 (b) Promptly after the termination of the GI Product Promotion
Term, GSK shall (a) immediately cease use of all Promotional Materials relating
to the GI Products in the United States, (b) return, or otherwise dispose of in
accordance with instructions from Adolor, all Promotional Materials relating to
the GI Products in the United States that remain in GSK's or its Affiliates'
possession or control, and (c) upon written request by Adolor provide Adolor
with a certified statement that all such remaining Promotional Materials
relating to the GI Products have been returned or otherwise properly disposed
of, and that GSK is no longer in possession or control of any such Promotional
Materials relating to the GI Products in the United States.

           7.1.9 Discontinued Use of Promotional Materials in the ROW. On a
                 ----------------------------------------------------
Collaboration Product-by-Collaboration Product and Country-by-Country basis in
the ROW, in the event this Agreement is terminated prior to expiration of the
ROW Term, GSK shall (a) immediately cease use of all promotional materials in
such Country in the ROW, (b) return, or otherwise dispose of in accordance with
instructions from Adolor, all promotional materials in such Country in the ROW
that remain in GSK's or its Affiliates' or sublicensees' possession or control,
and (c) upon written request by Adolor provide Adolor with a certified statement
that all such remaining promotional materials in such Country in the ROW have
been returned or otherwise properly disposed of, and that GSK is no longer in
possession or control of any such promotional materials in such Country in the
ROW.

     7.2   Samples for the United States.
           -----------------------------

           7.2.1 Make-Up of Package and Package Inserts of Samples. In the
                 -------------------------------------------------
United States, packaging, package inserts and outserts, Sample labels and
labeling shall each contain appropriate reference to Adolor and GSK with equal
exposure and prominence as may be permitted under applicable FDA rules and
regulations including, without limitation, 21 C.F.R. (S) 201.1(h). The Parties
agree to cooperate and use Commercially Reasonable Efforts to secure such
approval from the FDA.

           7.2.2 Shipment, Storage and Allocation of Samples. Reasonable
                 -------------------------------------------
requirements of Samples for the United States shall be shipped to each Party's
or its designee's distribution facility in a timely manner in accordance with
the schedule for distribution as outlined in the U.S. Marketing Plan. Each Party
shall be responsible for supplying its Sales Representatives in the United
States with Samples from such Party's or its designee's distribution facility.

                                      -66-

<PAGE>

           7.2.3 Sampling in the United States. Each Party shall use Samples in
                 -----------------------------
the United States strictly in accordance with the then-current U.S. Marketing
Plan and shall distribute Samples in full compliance with all applicable Laws,
including the requirements of the Prescription Drug Marketing Act of 1987, as
amended (the "PDM Act"). Specifically, the Parties shall establish, maintain and
              -------
adhere to written procedures to assure that each Party and its professional
representatives comply with all requirements of the PDM Act. Such procedures
shall include a requirement that each Party notify the other immediately upon
learning that any Samples shipped by to a Party have been lost or have not been
received as scheduled. Each Party will maintain records as required by the PDM
Act and all other Laws and shall allow representatives of the other Party to
inspect such records on request. Each Party shall be responsible for the filing
of any necessary reports to FDA in connection with the PDM Act, and a Party
shall provide the other Party in a timely fashion with any necessary information
in connection with such reporting under the PDM Act.

           7.2.4 Audit Rights in the United States in Relation to Sampling. Upon
                 ---------------------------------------------------------

reasonable advance notice to a Party, the other Party shall be entitled, at such
Party's expense, to conduct an inspection and audit of the other Party's Sample
distribution practices by its Sales Representatives in the United States and any
of such Party's owned or controlled facilities where Samples are stored. Such
inspection and audit shall be made in accordance with the applicable provisions
of the PDM Act and with the provisions of this Agreement.

                                   ARTICLE 8
                INFORMATION CONCERNING THE COLLABORATION PRODUCTS

     8.1  Statements Consistent with Labeling. Neither Party shall make, nor
          -----------------------------------
permit its Sales Representatives to make, any promotional statement,
representation or warranty, oral or written, concerning Collaboration Products
inconsistent with, or contrary to, the approved Collaboration Product labeling
or Promotional Materials. In addition, each Party shall insure that its Sales
Representatives Detail the Collaboration Products in a fair and balanced manner
in the United States and the ROW and consistent with the requirements of the
Federal Food, Drug and Cosmetic Act of the United States, as amended, including,
but not limited to, the regulations at 21 C.F.R. (S) 202 in the United States.

     8.2  Medical Inquiries. Adolor shall identify to GSK the Person or Persons
          -----------------
to whom GSK and its Affiliates shall refer all medical questions or inquiries
from members of the medical and paramedical professions and consumers regarding
the Adolor Products in the United States that GSK and its Affiliates cannot
readily answer by reference to the Adolor Product literature. GSK shall identify
to Adolor the Person or Persons to whom Adolor and its Affiliates shall refer
all medical questions or inquiries from members of the medical and paramedical
professions and consumers regarding the GI Product in the United States and the
Collaboration Products in the ROW that Adolor and its Affiliates cannot readily
answer by reference to the GI Product literature or Collaboration Product
literature, as applicable. Each Party shall use Commercially Reasonable Efforts
to refer,

                                  -67-

<PAGE>

and to cause its Affiliates to refer, all such medical questions or inquiries to
such identified Person or Persons.

     8.3  Standard Operating Procedures. Within ninety (90) days after the
          -----------------------------
Effective Date, the Parties shall develop a set of standard operating procedures
for responding promptly to medical questions or inquiries in the United States
from members of the medical and paramedical professions and consumers relating
to the Collaboration Products. In addition, the Parties will develop processes
to train personnel of each Party to respond consistently to such questions or
inquiries. For Collaboration Products in the ROW, GSK will follow appropriate
standard operating procedures consistent with all applicable Laws.

                                   ARTICLE 9
                               REGULATORY MATTERS

     9.1  Communications and Meetings with Governmental Authorities.
          ---------------------------------------------------------

          9.1.1 By GSK. Subject to the provisions of the Pharmacovigilance
                ------
Agreement, GSK shall not, without the consent of Adolor, correspond or
communicate with any Governmental Authority in the United States concerning the
Adolor Products, or otherwise take any action with any Governmental Authority in
the United States concerning any Investigational Authorization or Marketing
Authorization or permission under which the Adolor Products are sold or any
application for the same, except as may be required by Law. Furthermore, GSK
shall, promptly upon receipt of any material contact with or communication from
any Governmental Authority relating to a Collaboration Product, but in no event
more than two (2) Business Days after such receipt or contact, forward a copy or
description of the same to Adolor and respond to all reasonable inquiries by
Adolor relating thereto. GSK shall notify Adolor of any meeting with a
Governmental Authority relating to a Collaboration Product and Adolor may elect
one person reasonably acceptable to GSK (such approval not to be unreasonably
withheld, refused, conditioned or delayed) to participate as an observer (at
Adolor's cost and expense) in such meeting. If GSK is advised by its counsel
that it must communicate with any Governmental Authority, then GSK shall
promptly, but in no event more than two (2) Business Days, advise Adolor of the
same and provide Adolor in advance with a copy of any proposed written
communication with such Governmental Authority and comply with any and all
reasonable requests of Adolor concerning any meeting or written or oral
communication with such Governmental Authority.

          9.1.2  By Adolor. Subject to the provisions of the Pharmacovigilance
                 ---------
Agreement, Adolor shall not, without the consent of GSK, correspond or
communicate with any Governmental Authority in the United States concerning the
GI Products, or otherwise take any action with any Governmental Authority in the
United States concerning any Marketing Authorization or permission under which
the GI Products are sold or any application for the same, except as may be
required by Law. Furthermore, Adolor shall, promptly upon receipt of any
material contact

                                    -68-

<PAGE>

with or communication from any Governmental Authority relating to a
Collaboration Product, but in no event more than two (2) Business Days after
such receipt or contact, forward a copy or description of the same to GSK and
respond to all reasonable inquiries by GSK relating thereto. Adolor shall notify
GSK of any meeting with a Governmental Authority relating to a Collaboration
Product and GSK may elect one person reasonably acceptable to Adolor (such
approval not to be unreasonably withheld, refused, conditioned or delayed) to
participate as an observer (at GSK's cost and expense) in such meeting. If
Adolor is advised by its counsel that it must communicate with any Governmental
Authority, then Adolor shall promptly, but in no event more than two (2)
Business Days, advise GSK of the same and provide GSK in advance with a copy of
any proposed written communication with such Governmental Authority and comply
with any and all reasonable requests of GSK concerning any meeting or written or
oral communication with such Governmental Authority.

          9.1.3  Notification by Adolor of any Governmental Actions. Adolor
                 --------------------------------------------------
shall promptly, but in no event more than two (2) Business Days after receipt of
any inspections, proposed regulatory actions, investigations or requests by any
Governmental Authority with respect to the Adolor Products in the United States,
as well as any corrective actions initiated by Adolor with respect thereto,
notify GSK in detail with respect thereto and will provide GSK with copies of
all material related documentation. GSK shall have the right to participate in
all material preparation, internal caucus, and debriefing sessions related to
meetings or discussions to the extent practicable, whether in person, by
teleconference or otherwise, between Adolor or its agents and any Governmental
Authority with respect to the Adolor Products in the United States, and Adolor
shall provide GSK with reasonable prior written notice of any such sessions and
copies of meeting minutes with respect thereto.

          9.1.4  Notification by GSK of any Governmental Actions. GSK shall
                 -----------------------------------------------
promptly, but in no event more than two (2) Business Days after receipt of any
inspections, proposed regulatory actions, investigations or requests by any
Governmental Authority with respect to the GI Products in the United States and
with respect to the Collaboration Product in ROW, as well as any corrective
actions initiated by GSK with respect thereto, notify Adolor in reasonable
detail with respect thereto and will provide Adolor with copies of all material
related documentation. Adolor shall have the right to participate in all
material preparation, internal caucus, and debriefing sessions related to
meetings or discussions to the extent practicable, whether in person, by
teleconference or otherwise, between GSK or its agents and any Governmental
Authority with respect to the GI Products in the United States and with respect
to the Collaboration Product in ROW, and GSK shall provide Adolor with
reasonable prior written notice of any such sessions and copies of meeting
minutes with respect thereto.

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<PAGE>

    9.2  Filings with Governmental Authorities.
          -------------------------------------

          9.2.1  Adolor Products in the United States. Adolor will be solely
                 ------------------------------------
responsible for and will use Commercially Reasonable Efforts in applying for,
obtaining and maintaining Investigational Authorizations and Marketing
Authorizations for the Adolor Products in the United States, including without
limitation the responsibility for applying for price approvals for the Adolor
Products if required. Upon request by Adolor, GSK shall use Commercially
Reasonable Efforts to assist Adolor in applying for, obtaining and maintaining
such Investigational Authorizations and Marketing Authorizations (including,
with respect to price approvals, as requested by Adolor) for the Adolor Products
in the United States. Adolor will be the sole owner of any Investigational
Authorizations and Marketing Authorizations for the Adolor Products in the
United States. Upon receipt of the initial Investigational Authorizations and
Marketing Authorization for the Adolor Products in the United States, Adolor
shall have exclusive authority and responsibility to and will use Commercially
Reasonable Efforts to maintain and seek appropriate revisions of the conditions
of each such Investigational Authorization and Marketing Authorization for the
Adolor Products, provided any such revisions are not inconsistent with the
provisions of this Agreement or the U.S. Marketing Plan. Adolor shall promptly
and in accordance with applicable Law provide to GSK copies of any material
documents or correspondence received from any Governmental Authority in the
United States, but in no event more than two (2) Business Days after such
receipt, that pertains to the Adolor Products (including without limitation any
minutes from a meeting with respect thereto). In addition, Adolor shall provide
GSK with drafts of any material documents or correspondence to be submitted to
any Governmental Authority in the United States that pertains to the Adolor
Products. Adolor will consult in advance with, and consider in good faith any
comments of, GSK with respect to any filings made or other actions taken by
Adolor in accordance with the terms of this Section 9.2, including without
limitation any such filings or actions with respect to any changes or
modification to labeling for or the indications of the Adolor Products.

          9.2.2  GI Products in the United States. Subject to Sections 4.2 and
                 --------------------------------
5.4, GSK will be solely responsible for and will use Commercially Reasonable
Efforts in applying for, obtaining and maintaining Investigational
Authorizations and Marketing Authorizations for the GI Products in the United
States, including without limitation the responsibility for applying for price
approvals for the GI Products if required. Upon request by GSK, Adolor shall use
Commercially Reasonable Efforts to assist GSK in applying for, obtaining and
maintaining such Investigational Authorizations and Marketing Authorizations
(including, with respect to price approvals, as requested by GSK) for the GI
Products in the United States. GSK will be the sole owner of any Investigational
Authorizations and Marketing Authorizations for the GI Products in the United
States. Upon receipt of the initial Investigational Authorization and Marketing
Authorization for the GI Products in the United States, GSK shall have exclusive
authority and responsibility to and will use Commercially Reasonable Efforts to
maintain and

                                      -70-

<PAGE>

seek appropriate revisions of the conditions of each such Investigational
Authorization and Marketing Authorization for the GI Products, provided any such
revisions are not inconsistent with the provisions of this Agreement or the U.S.
Marketing Plan. GSK shall promptly and in accordance with applicable Law provide
to Adolor copies of any material documents or correspondence received from any
Governmental Authority in the United States, but in no event more than two (2)
Business Days after such receipt, that pertains to the GI Products (including
without limitation any minutes from a meeting with respect thereto). In
addition, GSK shall provide Adolor with drafts of any material documents or
correspondence to be submitted to any Governmental Authority in the United
States that pertains to the GI Products. GSK will consult in advance with, and
consider in good faith any comments of, Adolor with respect to any filings made
or other actions taken by GSK in accordance with the terms of this Section 9.2,
including without limitation any such filings or actions with respect to any
changes or modification to labeling for or the indications of the GI Products.

          9.2.3  Disputes Concerning Regulatory Matters. All disputes concerning
                 --------------------------------------
regulatory matters shall be resolved by the appropriate committee in accordance
with Article 3.

     9.3  In the ROW. Subject to Sections 4.2 and 5.4, GSK will be solely
          ----------
responsible for and will use Commercially Reasonable Efforts in applying for,
obtaining and maintaining Investigational Authorizations and Marketing
Authorizations for the Collaboration Products in the ROW, including without
limitation the responsibility for applying for price approvals for the
Collaboration Products if required. GSK will be the sole owner of any
Investigational Authorizations and Marketing Authorizations for the
Collaboration Products in the ROW. Upon receipt of the initial Investigational
Authorization and Marketing Authorization for the Collaboration Products in the
ROW, GSK shall have exclusive authority and responsibility to and will use
Commercially Reasonable Efforts to maintain and seek appropriate revisions of
the conditions of each such Investigational Authorization and Marketing
Authorization for the Collaboration Products, provided any such revisions are
not inconsistent with the provisions of this Agreement or the Commercialization
of Products in the United States. GSK shall promptly and in accordance with
applicable Laws, but in no event more than five (5) Business Days after such
receipt, provide to Adolor copies of any material documents or correspondence
received from any Governmental Authority in a Major Market Country relating to
the Adolor Products (including without limitation any minutes from a meeting
with respect thereto). In addition, GSK shall provide Adolor with drafts of any
material documents or correspondence to be submitted to any Governmental
Authority in a Major Market Country that pertains to the Adolor Products. GSK
will consult in advance with and, subject to the terms of Section 9.1 and the
Pharmacovigilance Agreement, and consistent with this Section 9.2, GSK will not
file any such material document with any Governmental Authority in a Major
Market Country relating to the Collaboration Products that could have an effect
on the Adolor Products in the United States without the prior written consent of
Adolor, such consent not to be unreasonably withheld, refused, conditioned or
delayed; provided that if Adolor does not respond to GSK within

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<PAGE>

two (2) Business Days after receipt of a copy of such material document, GSK
shall be permitted to file such material document without the prior written
consent of Adolor.

     9.4  Approval of Labeling and Promotional Materials.
          ----------------------------------------------

          9.4.1  By Adolor. Subject to the provisions of this Article 9, Adolor,
                 ---------
in the United States, shall have sole authority and responsibility to seek
and/or obtain any necessary Governmental Authority approvals of any label,
labeling, package inserts or outserts, monographs and packaging, and Promotional
Materials that are approved by the Joint Marketing Committee for use in
connection with the Adolor Products, and for determining whether the same
requires Governmental Authority approval. Upon request by Adolor, GSK shall use
Commercially Reasonable Efforts to assist Adolor in its efforts to seek and
obtain such Governmental Authority approvals.

          9.4.2  By GSK. Subject to the provisions of this Article 9, GSK, in
                 ------
the United States, shall have sole authority and responsibility to seek and/or
obtain any necessary Governmental Authority approvals of any label, labeling,
package inserts or outserts, monographs and packaging, and Promotional Materials
that are approved by the Joint Marketing Committee for use in connection with
the GI Products, and for determining whether the same requires Governmental
Authority approval. Upon request by GSK, Adolor shall use Commercially
Reasonable Efforts to assist GSK in its efforts to seek and obtain such
Governmental Authority approvals.

          9.4.3  Committee Approval. Subject to Section 3.1.4(b), no
                 ------------------
Collaboration Product label, labeling, package inserts or outserts, monographs,
packaging or Promotional Materials may be used or distributed by either Party in
the United States unless such label, labeling, package inserts or outserts,
monographs, packaging or Promotional Materials have been approved in advance by
the Joint Marketing Committee or the Joint Steering Committee.

     9.5  Regulatory Information.
          ----------------------

          9.5.1  Assistance. Subject to the terms of Section 9.1, in the United
                 ----------
States, each Party agrees to provide the other with all reasonable assistance
and take all actions reasonably requested by the other Party that are necessary
or desirable to enable the other Party to comply with any Law applicable to the
Collaboration Products, including, but not limited to, Adolor meeting its
reporting and other obligations to maintain and update any Marketing
Authorizations for the Collaboration Products.

          9.5.2  Notice. Each Party shall provide the other Party with notice,
                 ------
in a sufficiently timely basis to enable the other Party to comply in all
material respects with applicable Laws, of notification or other information
which it receives (directly or indirectly) from, any Governmental Authority (and
providing, as soon as reasonably possible, copies of any associated written
requests) that (i) raises any

                                      -72-

<PAGE>

material concerns regarding the safety or efficacy of a Collaboration Product,
(ii) indicates or suggests a Claim of a Third Party arising in connection with a
Collaboration Product, or (iii) is reasonably likely to lead to a recall or
market withdrawal of a Collaboration Product, provided that neither Party shall
be obliged to disclose information in breach of any contractual restriction
which it could not reasonably have avoided. Information that shall be disclosed
pursuant to this Section 9.5.2 shall include, but not be limited to:

                 (a)  Inspections by a Governmental Authority of manufacturing,
distribution or other related facilities concerning a Collaboration Product;

                 (b)  Inquiries by a Governmental Authority concerning clinical
investigation activities (including without limitation inquiries regarding
investigators, clinical monitoring organizations and other related parties) with
respect to a Collaboration Product;

                 (c)  Any communication from a Governmental Authority involving
the manufacture, sale, promotion or distribution of a Collaboration Product, or
any other Governmental Authority reviews or inquiries relating to a any event
set forth in this Section 9.5.2;

                 (d)  An initiation of any Governmental Authority investigation,
detention, seizure or injunction concerning a Collaboration Product; and

                 (e)  Any other regulatory action (e.g., proposed labeling or
other registrational dossier changes and recalls) which would affect a
Collaboration Product in any Country.

     9.6  Exchange of Drug Safety Information. Within ninety (90) days after the
          -----------------------------------
Effective Date, the Parties shall enter into the Pharmacovigilance Agreement.
Each Party shall ensure that, in the Development or Commercialization of the
Collaboration Products, it and each of its respective Affiliates will record,
investigate, summarize, notify, report and review all Adverse Drug Experiences
in accordance with Law and the Pharmacovigilance Agreement. Each Party shall
require that such Affiliates (i) adhere to all requirements of applicable Laws
which relate to the reporting and investigation of Adverse Drug Experiences, and
(ii) keep the Parties informed of such events.

     9.7  Recalls Or Other Corrective Action.
          ----------------------------------

          9.7.1  In the United States.
                 --------------------

                 (a)  Adolor shall promptly notify GSK of any material actions
to be taken by Adolor with respect to any recall or market withdrawal or other
corrective action related to the Adolor Products in the United States prior to
such action so as to permit GSK a reasonable opportunity to consult with Adolor
with respect thereto. Adolor agrees to consider GSK's consultation; provided,
however, nothing in this Section is intended to limit Adolor's ability to
recall, withdraw or take any other corrective

                                      -73-

<PAGE>

action relating to the Adolor Products in the United States. At Adolor's
request, GSK shall provide reasonable assistance to Adolor in conducting such
recall, market withdrawal or other corrective action in the United States. In
accordance with the foregoing, Adolor shall make all decisions with respect to
any recall, market withdrawals or any other corrective action related to the
Adolor Products in the United States.

                 (b)  GSK shall promptly notify Adolor of any material actions
to be taken by GSK with respect to any recall or market withdrawal or other
corrective action related to the GI Products in the United States prior to such
action so as to permit Adolor a reasonable opportunity to consult with GSK with
respect thereto. To the extent Adolor reasonably believes any such action is
likely to adversely affect the POI Product in the United States, Adolor shall
notify GSK and GSK shall not take any action without the prior written consent
of Adolor unless otherwise required by Law. In accordance with the foregoing,
GSK shall have sole responsibility for and shall make all decisions with respect
to any recall, market withdrawals or any other corrective action related to the
GI Products in the United States.

                 (c)  Each Party shall, as soon as practicable, notify the other
Party of any recall information received by it in sufficient detail to allow the
Parties to comply with any and all applicable Laws.

                 (d)  Any documented, direct, out-of-pocket costs incurred
(i.e., paid or accrued) by a Party with respect to participating in such recall,
market withdrawal or other corrective action in the United States shall be
deemed a Marketing Expense of such Party; provided, however, that if such
recall, market withdrawal or other corrective action was caused by a Party's
negligence, willful misconduct or breach of this Agreement occurring while the
Collaboration Product was under such Party's or its distributors or
manufacturers' control (e.g., mishandling or adulteration of the Collaboration
Product in such Party's or its distributor's or manufacturers' warehouse), such
Party shall reimburse the other Party for such costs and they shall not be
deemed a Marketing Expense. In no event shall a Party or its Affiliates or
sublicensees be deemed a distributor or manufacturer of the other Party under
the preceding sentence.

          9.7.2  In the ROW. GSK shall promptly notify Adolor of any material
                 ----------
actions to be taken by GSK with respect to any recall or market withdrawal or
other corrective action related the Collaboration Products in the ROW prior to
such action to permit Adolor a reasonable opportunity to consult with GSK with
respect thereto. To the extent Adolor reasonably believes any such action is
likely to adversely affect the POI Product in the United States, Adolor shall
notify GSK and GSK shall not take any action without the prior written consent
of Adolor unless otherwise required by Law. All costs and expenses with respect
to a recall, market withdrawal or other corrective action in the ROW shall be
borne by GSK unless such recall, market withdrawal or other corrective action
was due solely to

                                      -74-

<PAGE>

the negligence, willful misconduct or breach of this Agreement by Adolor. In
accordance with the foregoing, GSK shall have sole responsibility for and shall
make all decisions with respect to any recall, market withdrawals or any other
corrective action related to the Collaboration Products in the ROW.

     9.8  Events Affecting Integrity or Reputation. During the Term, the Parties
          ----------------------------------------
shall notify each other immediately of any circumstances of which they are aware
and which could impair the integrity and reputation of the Collaboration
Products or if a Party is threatened by the unlawful activity of any Third Party
in relation to the Collaboration Products, which circumstances shall include, by
way of illustration, deliberate tampering with or contamination of the
Collaboration Products by any Third Party as a means of extorting payment from
the Parties or another Third Party. In any such circumstances, the Parties shall
use Commercially Reasonable Efforts to limit any damage to the Parties and/or to
the Collaboration Products. The Parties shall promptly call a Joint Steering
Committee meeting to discuss and resolve such circumstances.

     9.9  Sharing of Regulatory Filings. GSK shall permit Adolor access to and
          -----------------------------
grant Adolor the right to reference and use, in association with the
Collaboration Products and the Combination Products, all data, regulatory
filings and regulatory communications associated with any submissions for
Investigational Authorization or Marketing Authorization or other issues
associated with any Collaboration Product or GSK Other GI Product that is or
would be relevant to Adolor's Development or Commercialization of a
Collaboration Product or Combination Product. Adolor shall permit GSK access to
and grant GSK the right to reference and use, in association with the
Collaboration Products, all data, regulatory filings and regulatory
communications associated with any submissions for Investigational Authorization
or Marketing Authorization or other issues associated with any Collaboration
Product or, subject to any Third Party Rights, Combination Products, that is or
would be relevant to GSK's Development or Commercialization of a Collaboration
Product. To the extent that any such data, regulatory filings or regulatory
communications are held by a Third Party, then Adolor or GSK, as the case may
be, shall endeavor to arrange direct access to the portions of such data,
regulatory filings or regulatory communications that are relevant to the
activities of the other Party that are contemplated by this Agreement.

                                   ARTICLE 10
                           ORDERS; SUPPLY AND RETURNS

     10.1 Orders and Terms of Sale in the United States for Adolor Products.
          -----------------------------------------------------------------
Except as otherwise expressly set forth in Section 5.5.2(b) or the distribution
services agreement contemplated in Section 6.3.3, Adolor shall have the sole
right in the United States to (i) receive, accept and fill orders for the Adolor
Products, (ii) control invoicing, order

                                      -75-

<PAGE>

processing and collection of accounts receivable for the sales of the Adolor
Products and (iii) record the sales of the Adolor Products in its books of
account.

     10.2 Orders and Terms of Sale in the United States for GI Products. Except
          -------------------------------------------------------------
as otherwise expressly stated in this Agreement, GSK shall have the sole right
in the United States to (i) receive, accept and fill orders for the GI Products,
(ii) control invoicing, order processing and collection of accounts receivable
for the sales of the GI Products and (iii) record the sales of the GI Products
in its books of account.

     10.3 Orders and Terms of Sale in the ROW. Except as otherwise expressly
          -----------------------------------
stated in this Agreement, GSK shall have the sole right in the ROW to (i)
receive, accept and fill orders for the Collaboration Products, (ii) control
invoicing, order processing and collection of accounts receivable for the
Collaboration Products sales, (iii) record the Collaboration Products sales in
its books of account, and (iv) establish and modify the commercial terms and
conditions with respect to the sale and distribution of the Collaboration
Products, including without limitation matters such as the price at which the
Collaboration Products will be sold and whether any discounts, rebates or other
deductions should be made, paid or allowed.

     10.4 Misdirected Orders. If, for any reason, GSK receives orders for the
          ------------------
Adolor Products in the United States, GSK shall forward such orders to Adolor
(or if directed by Adolor to Adolor's wholesalers) as soon as practicable. If,
for any reason, Adolor receives orders for the GI Products in the United States
or for the Collaboration Products in the ROW, Adolor shall forward such orders
to GSK (or if directed by GSK to GSK's wholesalers) as soon as practicable.

     10.5 Product Returns.
          ---------------

          10.5.1 Adolor Product Returns. If any quantities of an Adolor Product
                 ----------------------
are returned to GSK in the United States, GSK shall immediately notify Adolor
and ship them to the facility designated by Adolor, with any reasonable or
authorized shipping or other documented direct cost to be paid by Adolor. GSK,
at its option, may advise the customer who made the return that the Adolor
Product should have been returned to Adolor, but shall take no other steps in
respect of any return without the consent of Adolor, such consent not to be
unreasonably withheld, refused, conditioned or delayed. At Adolor's request, GSK
shall destroy the Adolor Product, the cost of such destruction to be deemed a
Marketing Expense; provided, however, that in the event the Adolor Product is
returned as a result of Adolor's breach of this Agreement, or otherwise as a
result of Adolor's negligence, than any costs associated with such destruction
shall be the sole responsibility of Adolor.

          10.5.2 GI Product Returns. If any quantities of an GI Product are
                 ------------------
returned to Adolor in the United States, Adolor shall immediately notify GSK and
ship them to the facility designated by GSK, with any reasonable or authorized
shipping or other documented direct cost to be paid by GSK. Adolor, at its
option, may advise the customer who made the return that the GI Product should
have been returned to GSK, but shall take no other steps in respect of any
return without the consent of GSK, such consent not to be unreasonably withheld,
refused, conditioned or delayed. At GSK's request, Adolor shall destroy the GI
Product, the cost of such destruction to be deemed a Marketing Expense;
provided, however, that in the event the GI Product is returned as a result of
GSK's breach of this Agreement, or

                                      -76-

<PAGE>

otherwise as a result of GSK's negligence, than any costs associated with such
destruction shall be the sole responsibility of GSK.

     10.6 Supply of API Compound and Collaboration Product for Development of
          -------------------------------------------------------------------
Collaboration Products.
----------------------

          10.6.1 Supply of API Compound for Development. Subject to the terms
                 --------------------------------------
and conditions of this Agreement, Adolor shall be responsible to supply, or to
obtain supply, for worldwide requirements of API Compound to enable the Parties
to fulfill their obligations to Develop Collaboration Products under this
Agreement. API Compound requirements for Development activities shall be set
forth in the relevant U.S. Development Plans and ROW Development Plans and shall
be periodically updated by the Joint Supply Committee in coordination with the
Joint Development Committee and the Joint Steering Committee.

          10.6.2 Supply of Formulated Collaboration Products for Development.
                 -----------------------------------------------------------
Subject to the terms and conditions of this Agreement, Adolor shall be
responsible to supply, or to obtain supply, for GSK's worldwide requirements of
formulated GI Products and GSK's ROW requirements of formulated Adolor Products
to enable GSK to fulfill its obligations to Develop Collaboration Products until
such time as GSK can supply such formulated Collaboration Products alone or with
Third Parties. Formulated Collaboration Product requirements for Development
activities shall be set forth in the relevant U.S. Development Plans and ROW
Development Plans and shall be periodically updated by the Joint Supply
Committee in coordination with the Joint Development Committee and the Joint
Steering Committee.

          10.6.3 Cost of Supply. Adolor shall supply such API Compound and such
                 --------------
formulated Collaboration Products to GSK at Adolor' Cost of Goods therefor and
GSK shall be responsible for shipping, insurance and other related expenses. For
the time period from the Effective Date through **, the Cost of Goods for API
Compound shall **, unless otherwise mutually agreed between the Parties.
Thereafter, Adolor will use Commercially Reasonable Efforts to provide a Cost of
Goods for API Compound **, unless otherwise mutually agreed between the Parties,
to be adjusted for inflation commencing with the Calendar Year beginning January
1, 2004, using the Producer Price Index as published by the Bureau of Labor
Statistics of the U.S. Department of Labor; provided Adolor will use
Commercially Reasonable Efforts to decrease the cost of such API Compound and
formulated Collaboration Products. GSK shall pay for such API Compound in
advance to the extent that Adolor is required to make payments in advance to its
Product Supplier.

          10.6.4 Clinical Supply Agreement. Within ** (**) days after the
                 -------------------------
Effective Date, the Parties shall negotiate and agree in good faith a
supply agreement relating to supply to GSK of its worldwide requirements of API
Compound and its short-term requirements of formulated Collaboration Products
for Development activities, addressing the standard terms of supply set forth in

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -77-

<PAGE>

Section 10.11 (the "Standard Terms") and relevant other terms relating to
                    --------------
specifications and quantities required. The Parties acknowledge that Product
Suppliers engaged by Adolor will carry out such manufacture and supply on
Adolor's behalf. Upon receipt of any API Compound supplied under such supply
agreement, GSK shall have thirty (30) days to perform the Testing Protocol to
determine if such API Compound conforms to the specifications and GSK shall
promptly notify Adolor of any API Compound that does not conform to the
specifications. On an interim basis pending effectiveness of such a supply
agreement, Adolor shall use Commercially Reasonable Efforts to supply GSK with
GSK's supply requirements of API Compound and formulated Collaboration Products
for Development activities under this Agreement in the following amounts and
timeframes (a) ** grams as capsules in the ** Calendar Quarter of Calendar Year
200**, (b) ** grams as capsules at the end of ** Calendar Quarter of Calendar
Year 200**, (c) ** grams of API Compound in the ** Calendar Quarter of Calendar
Year 200**, (d) ** grams of API Compound in the ** Calendar Quarter of Calendar
Year 200**, and (e) ** kilograms at times to be agreed upon by the Joint Supply
Committee; provided, however, that GSK shall provide in conjunction with such
supply requirements more detail to Adolor in writing, sufficiently in advance of
the date needed and with sufficient regard to the lead times involved to enable
Adolor to procure such supply; provided, further, that such request from GSK
shall be subject to the condition that the requirements of API Compound and
formulated Collaboration Products for use in POI Products for Development and
Commercialization in the United States shall have first priority.

     10.7 Supply of API Compound for Commercialization of Collaboration
          -------------------------------------------------------------
Products.
--------

          10.7.1 Commercial Requirements for API Compound. Subject to the terms
                 ----------------------------------------
and conditions of this Agreement, Adolor shall be responsible to supply, or to
obtain supply, of API Compound to enable the Parties to fulfill their
obligations to Commercialize Collaboration Products under this Agreement. Such
API Compound shall be supplied in accordance with the principles set out in the
Standard Terms and relevant other terms relating to specifications and
quantities required. A forecast for API Compound requirements for
Commercialization of the Collaboration Products shall be prepared and
periodically updated by the Joint Supply Committee and coordinated with the
applicable U.S. Marketing Plans for Collaboration Products through the Joint
Marketing Committee and through the Joint Steering Committee for
Commercialization in the ROW.

          10.7.2 Cost of Supply. Adolor shall supply such API Compound to GSK at
                 --------------
** and GSK shall be responsible for shipping, insurance and other related
expenses. Adolor will use Commercially Reasonable Efforts to provide a Cost of
Goods for API Compound not to **, unless otherwise mutually agreed between the
Parties, to be adjusted for inflation commencing with the Calendar Year
beginning January 1, 200**, using the Producer Price Index as published by the
Bureau of Labor Statistics of the U.S. Department of Labor; provided Adolor will
use Commercially Reasonable Efforts

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -78-

<PAGE>

to decrease the cost of such API Compound. GSK shall pay for such API Compound
in advance to the extent that Adolor is required to make payments in advance to
its Product Supplier.

          10.7.3 Supply Agreement. Within one hundred eighty (180) days after
                 ----------------
the Effective Date, the Parties shall negotiate and agree in good faith a supply
agreement relating to supply to GSK of its worldwide commercial requirements of
API Compound incorporating the Standard Terms and relevant other terms relating
to specifications and quantities required. The Parties acknowledge that Product
Suppliers engaged by Adolor will carry out such manufacture and supply on
Adolor's behalf. Upon receipt of such API Compound, GSK shall have thirty (30)
days to perform the Testing Protocol to determine if such API Compound conforms
to the specifications and GSK shall promptly notify Adolor of any API Compound
that does not conform to the specifications.

          10.7.4 Right of First Negotiation. Subject to Adolor's existing
                 --------------------------
obligations to its Product Suppliers, GSK shall have a right of first
negotiation to become an alternative or primary source of supply of API Compound
for Commercialization of all Collaboration Products, at GSK's Cost of Goods
therefor, which shall not be greater than the applicable Product Supplier's Cost
of Goods, and Adolor shall consider any such proposal by GSK in good faith. The
Parties shall enter into a separate supply agreement if, in accordance with the
foregoing, GSK is chosen to become an alternative or primary Product Supplier of
API Compound; provided, however, that GSK's Cost of Goods for API Compound shall
in no event exceed the cost of API Compound as supplied, or as could be supplied
by a Third Party, as measured at the request of Adolor and no more frequently
than once per Calendar Year. In the event that GSK is established as a Product
Supplier, GSK shall be responsible for all costs and expenses related to any
necessary transfer of technology.

     10.8 Supply of Collaboration Products for Commercialization.
          ------------------------------------------------------

          10.8.1 Supply of Adolor Products in the United States. Subject to the
                 ----------------------------------------------
terms and conditions of this Agreement, Adolor shall be responsible to supply,
or to obtain supply, of commercial requirements of formulated, packaged and
labeled Adolor Products for the United States during the Adolor Product
Promotion Term. Such formulated, packaged and labeled Adolor Products for the
United States shall be supplied in accordance with the principles set out in the
Standard Terms and relevant other terms relating to specifications and
quantities required. The Joint Marketing Committee shall prepare and update
quarterly a rolling three (3) year forecast of the demand for the Adolor
Products by Calendar Quarter for the United States, which will be provided to
and monitored by the Joint Supply Committee. Notwithstanding the foregoing, the
Parties may determine that some or all of any aspect of secondary manufacturing
activity, including but not limited to formulation manufacturing, labeling and
packaging, of the Adolor Products may be performed by GSK on terms to be
determined by the Parties.

                                      -79-

<PAGE>

          10.8.2 Supply of GI Products in the United States. Subject to the
                 ------------------------------------------
terms and conditions of this Agreement, GSK shall be responsible to supply, or
to obtain supply, of the Parties' commercial requirements of formulated,
packaged and labeled GI Products for the United States during the GI Product
Promotion Term. Such formulated, packaged and labeled GI Products for the United
States shall be manufactured and supplied in accordance with the principles set
out in the Standard Terms and relevant other terms relating to specifications
and quantities required; provided, however, that GSK's Cost of Goods for
formulated, packaged and labeled GI Products for the United States shall in no
event exceed the cost of formulated, packaged and labeled GI Products as
supplied, or as could be supplied by a Third Party, as measured at the request
of Adolor and no more frequently than once per Calendar Year. The Joint
Marketing Committee shall prepare and update quarterly a rolling ** (**) year
forecast of the demand for the GI Products by Calendar Quarter for the United
States, which will be provided to and monitored by the Joint Supply Committee.

          10.8.3 Supply of Collaboration Products for the ROW. Subject to the
                 --------------------------------------------
terms and conditions of this Agreement, GSK shall be responsible to supply, or
to obtain supply, of the commercial requirements of formulated, packaged and
labeled Collaboration Products for the ROW during the ROW Term. Such formulated,
packaged and labeled Collaboration Products for the ROW shall be manufactured
and supplied in accordance with all applicable Laws and current Good
Manufacturing Practices. GSK shall be solely responsible for secondary
manufacture, packaging and labeling of the GI Products for Commercialization in
the United States and for Collaboration Products in the ROW. In order to give
effect to the foregoing, Adolor shall be responsible to supply, or to obtain
supply, for GSK's requirements of API Compound pursuant to Section 10.7.

     10.9 Shortages. Adolor shall give GSK written notice as soon as reasonably
          ---------
practicable if Adolor becomes aware that its Product Suppliers will not be able
to substantially satisfy the Parties' requirements for API Compound, and the
Parties shall give each other written notice as soon as reasonably practicable
if either Party becomes aware that its Product Suppliers will not be able to
substantially satisfy the Parties' requirements for formulated Collaboration
Products, for whatever reason. In the event that there is a failure to
substantially satisfy the Parties' requirements of API Compound or formulated
Collaboration Product, provided that such requirements cannot be satisfied by
the Parties' inventories of API Compound or formulated Collaboration Product,
and additionally provided that such failure will or does result in an
interruption of supply of Collaboration Products to the commercial market, then
GSK and Adolor will immediately work together, in good faith, to identify an
appropriate alternative source of API Compound or formulated Collaboration
Products supply, provided that:

          10.9.1 Efforts to Supply Requirements. Adolor shall use its
                 ------------------------------
Commercially Reasonable Efforts to supply the Parties' requirements for API
Compound in accordance with Section 3.4.2(c), and the Parties shall use their
Commercially Reasonable Efforts to supply the Parties' requirements for
formulated Collaboration Product; and

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -80-

<PAGE>

           10.9.2 Manufacturing by GSK During Shortage. GSK shall be entitled to
                  ------------------------------------
assume responsibility for supply and manufacture of API Compound or formulated
Collaboration Product for such period as the shortage may exist to address and
satisfy the Parties' requirements for such API Compound or formulated
Collaboration Product in the interim and, in order to facilitate same, Adolor
shall grant GSK the licenses set forth in Section 2.1.6 and, upon request,
effect any transfer of applicable data and information immediately forthwith.
The foregoing right of GSK to assume responsibility for supply and manufacture
of API Compound or formulated Collaboration Product shall also apply in the
event that Adolor's supply of API Compound or such Collaboration Product
repeatedly does not meet the respective specifications therefor.

     10.10 Product Suppliers. In order to fulfill their respective obligations
           -----------------
under this Article 10, and without prejudice to the terms and conditions of this
Article 10, Adolor and GSK shall each be responsible for: (a) entering into
appropriate supply agreements with Product Suppliers; (b) transferring
technology to such Product Suppliers; (c) where such Product Suppliers have not
already been appointed as of the Effective Date, obtaining approval from the
other Party, such approval not to be unreasonably withheld, refused, conditioned
or delayed and, for the avoidance of doubt, this requirement for consent shall
apply to the appointment of all Product Suppliers under or in connection with
this Agreement except Product Suppliers appointed by GSK in the ROW; and (d)
obtaining any necessary regulatory approval for the use of such Product
Suppliers. Adolor shall make payments to Product Suppliers under its control for
Adolor Products for sale and distribution in the United States. GSK shall make
payments to Product Suppliers under its control for GI Products for sale and
distribution in the United States and for Collaboration Products for sale and
distribution in the ROW.

     10.11 Standard Terms of Supply.
           ------------------------

           10.11.1 Product Supplier Representations. The Parties shall use
                   --------------------------------
Commercially Reasonable Efforts in negotiating and entering into supply
agreements with Product Suppliers **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -81-

<PAGE>

**

        10.11.2 Manufacturing Regulatory Matters. **
                --------------------------------
** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -82-

<PAGE>

**

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -83-

<PAGE>

**

           10.11.3 Continuous Improvement. Both Parties agree to use
                   ----------------------
Commercially Reasonable Efforts to continuously improve its performance and its
Product Suppliers' performance, including, but not limited to, cost of
Collaboration Products and API Compound, yield and delivery timing. The Parties
shall agree on targets to measure such performance improvements.

           10.11.4 Inventories. Both Parties, and their respective Product
                   -----------
Suppliers, shall maintain an inventory of API Compound and Collaboration
Products in accordance with their normal practices and so as to ensure
fulfillment of their respective supply obligations herein.

                                   ARTICLE 11
                                   GSK PRODUCT

     11.1  GSK Product Right and License. Subject to the terms of this
           -----------------------------
Agreement, GSK grants to Adolor, and Adolor accepts, the exclusive (except as to
GSK and its Affiliates) right, under the Patent Rights and Know-How of GSK and
under any copyrights or trademarks owned or controlled by GSK, to detail and
co-promote, or if appropriate, and the Parties mutually agree, to sell, through
itself or its Affiliates or subcontractors, ** prescription pharmaceutical
products of GSK that are, at the time of being proposed to Adolor, either being
marketed in the United States or in development for commercialization in the
United States and which shall be selected pursuant to Section 11.2 (the "GSK ---
Products"). --------

     11.2  Adolor Selection Process and Timeframe.
           --------------------------------------

           11.2.1  To give effect to the foregoing, **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -84-

<PAGE>

**

            11.2.2 It is hereby understood and acknowledged that **

     11.3 GSK Product Agreement. The terms and conditions of a GSK Product
          ---------------------
Agreement (including the term itself) will be negotiated by the Parties in good
faith, with the understanding that the Parties **

     11.4 No Selected GSK Product. **
          -----------------------

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -85-

<PAGE>

**

                                   ARTICLE 12
                            Confidential Information

     12.1 Confidential Information. Each of GSK and Adolor shall keep all
          ------------------------
Confidential Information received from the other Party with the same degree of
care it maintains the confidentiality of its own Confidential Information.
Neither Party shall use such Confidential Information for any purpose other than
in performance of this Agreement or disclose the same to any other Person other
than to such of its agents who have a need to know such Confidential Information
to implement the terms of this Agreement or enforce its rights under this
Agreement. A Receiving Party shall advise any agent who receives such
Confidential Information of the confidential nature thereof and of the
obligations contained in this Agreement relating thereto, and the Receiving
Party shall ensure that all such agents comply with such obligations as if they
had been a Party hereto. Upon termination of this Agreement, the Receiving Party
shall use Commercially Reasonable Efforts to return or destroy all documents,
tapes or other media containing Confidential Information of the Disclosing Party
that remain in the Receiving Party's or its agents' possession, except that the
Receiving Party may keep one copy of the Confidential Information in the legal
department files of the Receiving Party, solely for archival purposes. Such
archival copy shall be deemed to be the property of the Disclosing Party, and
shall continue to be subject to the provisions of this Article 12.
Notwithstanding anything to the contrary in this Agreement, the Receiving Party
shall have the right to disclose any Confidential Information provided hereunder
if, in the reasonable opinion of the Receiving Party's legal counsel, such
disclosure is necessary to comply with the terms of this Agreement, or the
requirements of any Law. Where possible, the Receiving Party shall notify the
Disclosing Party of the Receiving Party's intent to make such disclosure of
Confidential Information pursuant to the provision of the preceding sentence
sufficiently prior to making such disclosure so as to allow the Disclosing Party
adequate time to take whatever action the Disclosing Party may deem to be
appropriate to protect the confidentiality of the information.

     12.2 Permitted Disclosure and Use. Notwithstanding Section 12.1, a Party
          ----------------------------
may disclose Confidential Information belonging to the other Party only to the
extent such disclosure is reasonably necessary to: (a) obtain Marketing
Authorization of a Collaboration Product; (b) enforce the provisions of this
Agreement; or (c) comply with Laws. If a Party deems it necessary to disclose
Confidential Information of the other Party pursuant to this Section 12.2, such
Party shall give reasonable advance notice of such disclosure to the other Party
to permit such other Party sufficient opportunity to object to such disclosure
or to take measures to ensure confidential treatment of such information.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -86-

<PAGE>

     12.3 Publications. Subject to any Third Party rights existing as of the
          ------------
Effective Date, each Party shall submit to the Joint Development Committee or
Joint Marketing Committee, as applicable (hereinafter referred to as the
"Applicable Committee") for review and approval all proposed academic,
 --------------------
scientific and medical publications and public presentations relating to a
Collaboration Product or any research or Development activities under this
Agreement for review in connection with preservation of Patent Rights, and trade
secrets and/or to determine whether Confidential Information should be modified
or deleted from the proposed publication or public presentation. Written copies
of such proposed publications and presentations shall be submitted to the
Applicable Committee no later than sixty (60) days before submission for
publication or presentation and the Applicable Committee shall provide its
comments with respect to such publications and presentations within ten (10)
Business Days of its receipt of such written copy. The review period may be
extended for an additional thirty (30) days if a representative of the
non-publishing Party on the Applicable Committee can demonstrate a reasonable
need for such extension including, but not limited to, the preparation and
filing of patent applications. By mutual agreement of the Parties, this period
may be further extended. The Parties will each comply with standard academic
practice regarding authorship of scientific publications and recognition of
contribution of other parties in any publications relating to the Collaboration
Products or any research or Development activities under this Agreement.

     12.4 Public Announcements. Except as may be expressly permitted under
          --------------------
Section 12.3 or required by applicable Laws, neither Party will make any public
announcement of any information regarding this Agreement, the Collaboration
Products or any research or Development activities under this Agreement without
the prior written approval of the other Party. Once any written statement is
approved for disclosure by the Parties or information is otherwise made public
in accordance with the preceding sentence, either Party may make a subsequent
public disclosure of the contents of such statement without further approval of
the other Party.

     12.5 Confidentiality of this Agreement. The terms of this Agreement shall
          ---------------------------------
be Confidential Information of each Party and, as such, shall be subject to the
provisions of this Article 12.

     12.6 Survival. The obligations and prohibitions contained in this Article
          --------
12 shall survive the expiration or termination of this Agreement for a period of
ten (10) years.

                                   ARTICLE 13
                    REPRESENTATIONS AND WARRANTIES; COVENANTS

     13.1 Mutual Representations and Warranties. Adolor and GSK each represents
          -------------------------------------
and warrants to the other as of the Effective Date that:

          13.1.1 Such Party (a) is a company duly organized, validly existing,
and in good standing under the Laws of its incorporation; (b) is duly qualified
as a corporation and in good standing under the Laws of each jurisdiction where
its ownership or lease of property or the conduct of its business requires such
qualification, where

                                      -87-

<PAGE>

the failure to be so qualified would have a material adverse effect on its
financial condition or its ability to perform its obligations hereunder; (c) has
the requisite corporate power and authority and the legal right to conduct its
business as now conducted and hereafter contemplated to be conducted; (d) has or
will obtain all necessary licenses, permits, consents, or approvals from or by,
and has made or will make all necessary notices to, all Governmental Authorities
having jurisdiction over such Party, to the extent required for the ownership
and operation of its business, where the failure to obtain such licenses,
permits, consents or approvals, or to make such notices, would have a material
adverse effect on its financial condition or its ability to perform its
obligations hereunder; and (e) is in compliance with its charter documents;

          13.1.2 The execution, delivery and performance of this Agreement by
such Party and all instruments and documents to be delivered by such Party
hereunder (a) are within the corporate power of such Party; (b) have been duly
authorized by all necessary or proper corporate action; (c) do not conflict with
any provision of the charter documents of such Party; (d) will not, to the best
of such Party's knowledge, violate any law or regulation or any order or decree
of any court of governmental instrumentality; (e) will not violate or conflict
with any terms of any indenture, mortgage, deed of trust, lease, agreement, or
other instrument to which such Party is a party, or by which such Party or any
of its property is bound, which violation would have a material adverse effect
on its financial condition or on its ability to perform its obligations
hereunder;

          13.1.3 This Agreement has been duly executed and delivered by such
Party and constitutes a legal, valid and binding obligation of such Party,
enforceable against such Party in accordance with its terms, except as such
enforceability may be limited by applicable insolvency and other Laws affecting
creditors' rights generally, or by the availability of equitable remedies; and

          13.1.4 All of its employees, officers, and consultants have executed
agreements or have existing obligations under law requiring assignment to such
Party of all Inventions made by such individuals during the course of and as the
result of their association with such Party, and obligating such individuals to
maintain as confidential such Party's Confidential Information, as well as the
Confidential Information of Persons doing business with such Party that such
individuals may receive during the course of and as the result of their
association with such Party, to the extent required to support such Party's
obligations under this Agreement.

     13.2 Additional GSK Representations and Warranties. GSK further represents,
          ---------------------------------------------
warrants and covenants to Adolor that:

          13.2.1 It has utilized its own scientific, marketing and distribution
expertise and experience to analyze and evaluate both the scientific and
commercial value of the Compound and the Collaboration Products and has solely
relied on such analysis and evaluations in deciding to enter into this
Agreement;

                                      -88-

<PAGE>

          13.2.2 Neither GSK nor any of its Affiliates is a party to or
otherwise bound by any oral or written contract or agreement that will result in
any Person obtaining any interest in, or that would give to any Person any right
to assert any claim in or with respect to, any of GSK's rights under this
Agreement;

          13.2.3 GSK shall retain ownership or control of the right to permit
Adolor to promote or detail any GSK Product;

          13.2.4 There is no claim or demand of any person or entity pertaining
to, or any proceeding which is pending or, to the knowledge of GSK, threatened,
that challenges the rights of Adolor in respect of any GSK Know-How or GSK
Patents, or that claims that any default exists under any license with respect
to any GSK Know-How or GSK Patents to which GSK is a party, except where such
claim, demand or proceeding would not materially and adversely affect the
ability of GSK to carry out its obligations under this Agreement;

          13.2.5 As of the Effective Date, GSK and its Affiliates beneficially
own **, in addition to such other shares which may be held as trust assets of
pension plan trusts maintained by GSK and its Affiliates and managed by Third
Party investment managers; and

          13.2.6 Pursuant to the Hart Scott Rodino Antitrust Improvements Act of
1976 (the "HSR Act"), GSK has made the good faith determination that this
           -------
transaction does not satisfy the size of the transaction test as defined under
the HSR Act, and therefore, no filing is required under the HSR Act for this
transaction.

     13.3 Additional Adolor Representations and Warranties. Adolor further
          ------------------------------------------------
represents and warrants to GSK as of the Effective Date that:

          13.3.1 Adolor has not received notice from any Third Party of a claim
that an issued patent of such Third Party in the United States or the ROW would
be infringed by the manufacture, distribution, marketing or sale of the
Collaboration Products under this Agreement;

          13.3.2 To Adolor's knowledge, the Adolor Patents are not subject
anywhere in the United States or the ROW to any pending or any threatened,
re-examination, opposition, interference or litigation proceedings and Adolor
has requested and received confirmation of the same from Lilly;

           13.3.3 Adolor has not received notice from any Third Party of a claim
asserting the invalidity, misuse, unregisterability or unenforceability of any
of the Adolor Patents, or challenging its right to use or ownership of any of
the Adolor Patents or the Adolor Know-How, or making any adverse claim of
ownership thereof;

           13.3.4 Adolor has not received notice from any Third Party that any
trade secrets or other intellectual property rights of such Third Party in the
United States or the ROW would be misappropriated by the development and
reduction to practice of the Adolor Patents and Adolor Know-How;

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.
                                      -89-

<PAGE>

           13.3.5 Adolor has, up to and including the Effective Date, endeavored
in good faith to furnish GSK with all material information requested by GSK
concerning the quality, toxicity, safety and/or efficacy concerns that may
materially impair the utility and/or safety of the API Compound or Collaboration
Products;

           13.3.6 Pursuant to that certain License Agreement between Lilly and
Roberts Laboratories Inc. dated November 5, 1996 (the "Lilly Agreement") as
                                                       ---------------
assigned to Adolor by Roberts Laboratories Inc. pursuant to that certain Option
and License Agreement dated June 10, 1998, Adolor's licensor, **; and

           13.3.7 To Adolor' knowledge, the Lilly Agreement is valid, binding
and enforceable in accordance with its respective terms and Adolor has not
received any written notice of any material and continuing defaults, breaches or
violations under the Lilly Agreement.

     13.4  Covenants.
           ---------

           13.4.1 Each Party hereby covenants and agrees during the Term that it
shall carry out the Commercialization of the Collaboration Products and its
other obligations or activities hereunder in accordance with (i) the terms of
this Agreement and (ii) all applicable Laws.

           13.4.2 Each Party hereby covenants and agrees during the Term that it
will not enter into any agreement with a Third Party or undertake other
activities or commitments, including any such agreement or any such activities
or commitments related to any Combination Product, which would have a material
adverse effect on (i) its ability to perform all of the obligations undertaken
by it and/or (ii) any of the rights granted to the other Party hereunder and/or
(iii) the commercial value of any of the Collaboration Products being Developed
and/or Commercialized under this Agreement. The Parties acknowledge that this
Section 13.4.2 shall not prevent Adolor from entering into an agreement with a
Third Party relating to a Combination Product. For purposes of clarity, it is
understood that any Collaboration Product which has been terminated in
accordance with this Agreement shall not be subject to the provisions of this
Section 13.4.2.


           13.4.3 Adolor hereby covenants and agrees during the Term that it
shall not knowingly and voluntarily take any action or refrain from taking any
action so as to give Lilly cause to terminate the Lilly Agreement.

     13.5  Disclaimer of Warranty. Nothing in this Agreement shall be construed
           ----------------------
as a warranty or representation by either Party (i) that any Collaboration
Product made, used, sold or otherwise disposed of under this Agreement is or
will be free from infringement of patents, copyrights, trademarks, industrial
design or other intellectual property rights of

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -90-

<PAGE>

any Third Party, (ii) regarding the effectiveness, value, safety, non toxicity,
patentability, or non-infringement of any patent technology, the Collaboration
Products or any information or results provided by either Party pursuant to this
Agreement or (iii) that any Collaboration Product will obtain Marketing
Authorization or appropriate pricing approval. Each Party explicitly accepts all
of the same as experimental and for development purposes, and without any
express or implied warranty from the other Party. EXCEPT AS OTHERWISE EXPRESSLY
SET FORTH IN THIS AGREEMENT, EACH PARTY EXPRESSLY DISCLAIMS, WAIVES, RELEASES,
AND RENOUNCES ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION,
ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

                                   ARTICLE 14
                                 INDEMNIFICATION

     14.1  Indemnification by GSK. Subject to Sections 2.4.8, 14.5 and 15.2, GSK
           ----------------------
shall defend, indemnify and hold harmless Adolor and its Affiliates and each of
their officers, directors, shareholders, employees, successors and assigns from
and against all Claims of Third Parties, and all associated Losses, to the
extent arising out of (a) GSK's negligence or willful misconduct in performing
any of its obligations under this Agreement, (b) a breach by GSK of any of its
representations, warranties, covenants or agreements under this Agreement, or
(c) the manufacture, use or sale of GI Products in the United States for GI
Products that Adolor is not receiving a percentage of GI Product Marketing
Contribution, or (d) the manufacture, use or sale of Collaboration Products in
the ROW; provided, however, that in all cases referred to in this Section 14.1,
GSK shall not be liable to indemnify Adolor for any Losses of Adolor to the
extent that such Losses of Adolor were caused by: (x) the negligence or willful
misconduct or wrongdoing of Adolor or (y) any breach by Adolor of its
representations, warranties, covenants or agreements hereunder.

     14.2  Indemnification by Adolor. Subject to Sections 2.4.8, 14.5 and 15.2,
           -------------------------
Adolor shall defend, indemnify and hold harmless GSK and its Affiliates and each
of their officers, directors, shareholders, employees, successors and assigns
from and against all Claims of Third Parties, and all associated Losses, to the
extent arising out of (a) Adolor's negligence or willful misconduct in
performing any of its obligations under this Agreement, (b) a breach by Adolor
of any of its representations, warranties, covenants or agreements under this
Agreement, (c) the manufacture, use, or sale of the Adolor Products in the
United States following the Adolor Product Promotion Term, or (d) the
manufacture, use, marketing or sale of any Product which Adolor develops or
commercializes without the participation of GSK; provided, however, that in all
cases referred to in this Section 14.2, Adolor shall not be liable to indemnify
GSK for any Losses of GSK to the extent that such Losses of GSK were caused by:
(x) the negligence or willful misconduct or wrongdoing of GSK or (y) any breach
by GSK of its representations, warranties, covenants or agreements hereunder.

                                      -91-

<PAGE>

     14.3  Procedure for Indemnification.
           -----------------------------

           14.3.1 Notice. Each Party will notify promptly the other if it
                  ------
becomes aware of a Claim (actual or potential) by any Third Party (other than
any Product Liability Claim provided for under Section 14.5) (a "Third Party
                                                                 -----------
Claim") for which indemnification may be sought by that Party and will give such
-----
information with respect thereto as the other Party shall reasonably request. If
any proceeding (including any governmental investigation) is instituted
involving any Party for which such Party may seek an indemnity under Section
14.1 or 14.2, as the case may be (the "Indemnified Party"), the Indemnified
                                       -----------------
Party shall not make any admission or statement concerning such Third Party
Claim, but shall promptly notify the other Party (the "Indemnifying Party")
                                                       ------------------
orally and in writing and the Indemnifying Party and Indemnified Party shall
meet to discuss how to respond to any Third Party Claims that are the subject
matter of such proceeding. The Indemnifying Party shall not be obligated to
indemnify the Indemnified Party to the extent any admission or statement made by
the Indemnified Party or any failure by such Party to notify the Indemnifying
Party of the claim materially prejudices the defense of such claim.

           14.3.2 Defense of Claim. If the Indemnifying Party elects to defend
                  ----------------
or, if local procedural rules or laws do not permit the same, elects to control
the defense of a Third Party Claim, it shall be entitled to do so provided it
gives notice to the Indemnified Party of its intention to do so within
forty-five (45) days after the receipt of the written notice from the
Indemnified Party of the potentially indemnifiable Third Party Claim (the
"Litigation Condition"); provided, that the Indemnifying Party expressly agrees
 --------------------
the Indemnifying Party shall be responsible for satisfying and discharging any
award made to the Third Party as a result of such proceedings or settlement
amount agreed with the Third Party in respect of the Third Party Claim without
prejudice to any provision in this Agreement or right at law which will allow
the Indemnifying Party subsequently to recover any amount from the Indemnified
Party to the extent the liability under such settlement or award was
attributable to the Indemnified Party. Subject to compliance with the Litigation
Condition, the Indemnifying Party shall retain counsel reasonably acceptable to
the Indemnified Party (such acceptance not to be unreasonably withheld, refused,
conditioned or delayed) to represent the Indemnified Party and shall pay the
fees and expenses of such counsel related to such proceeding. In any such
proceeding, the Indemnified Party shall have the right to retain its own
counsel, but the fees and expenses of such counsel shall be at the expense of
the Indemnified Party. The Indemnified Party shall not settle any claim for
which it is seeking indemnification without the prior consent of the
Indemnifying Party which consent shall not be unreasonably withheld, refused,
conditioned or delayed. The Indemnified Party shall, if requested by the
Indemnifying Party, cooperate in all reasonable respects in the defense of such
claim that is being managed and/or controlled by the Indemnifying Party. The
Indemnifying Party shall not, without the written consent of the Indemnified
Party (which consent shall not be unreasonably withheld, refused, conditioned or
delayed), effect any settlement of any pending or threatened proceeding in which

                                      -92-

<PAGE>

the Indemnified Party is, or based on the same set of facts could have been, a
party and indemnity could have been sought hereunder by the Indemnified Party,
unless such settlement includes an unconditional release of the Indemnified
Party from all liability on claims that are the subject matter of such
proceeding. If the Litigation Condition is not met, then neither Party shall
have the right to control the defense of such Third Party Claim and the Parties
shall cooperate in and be consulted on the material aspects of such defense at
the each Party's own expense; provided that if the Indemnifying Party does not
satisfy the Litigation Condition, the Indemnifying Party may at any subsequent
time during the pendency of the relevant Third Party Claim irrevocably elect, if
permitted by local procedural rules or laws, to defend and/or to control the
defense of the relevant Third Party Claim so long as the Indemnifying Party also
agrees to pay the reasonable fees and costs incurred by the Indemnified Party in
relation to the defense of such Third Party Claim from the inception of the
Third Party Claim until the date the Indemnifying Party assumes the defense or
control thereof.

     14.4  Assumption of Defense. Notwithstanding anything to the contrary
           ---------------------
contained herein, an Indemnified Party shall be entitled to assume the defense
of any Third Party Claim with respect to the Indemnified Party, upon written
notice to the Indemnifying Party pursuant to this Section 14.4, in which case
the Indemnifying Party shall be relieved of liability under Section 14.1 or
14.2, as applicable, solely for such Third Party Claim and related Losses.

     14.5  Product Liability Claims in the United States.
           ---------------------------------------------

           14.5.1 Except for such Claims for which GSK is obligated to indemnify
Adolor under Section 14.1 or Adolor is obligated to indemnify GSK under Section
14.2, each of Adolor and GSK shall be responsible for Losses (a) arising out of
or resulting from any and all Claims of Third Parties concerning the
Collaboration Products sold in the United States during the United States Term
and (b) that involve death or bodily injury (or allegations thereof) to any
individual (each, a "Product Liability Claims"). All Product Liability Claims
                     ------------------------
shall be shared in proportion to such Party's share of either the Adolor Product
Marketing Contribution or the GI Product Marketing Contribution, as applicable
and without taking into effect any adjustments to the Adolor Product Marketing
Contribution or GI Product Marketing Contribution pursuant to Section 6.3.4.
Notwithstanding the foregoing, Adolor shall not be responsible for any Losses
arising out of or resulting from Product Liability Claims in relation to
Collaboration Product for which it does not receive a percentage of the Adolor
Product Marketing Contribution or a percentage of the GI Product Marketing
Contribution unless such Loss is related to a Claim under Section 14.2(a) or
14.2(b).

           14.5.2 Each Party shall give the other prompt written notice of any
Product Liability Claim (actual or potential), but the omission of such notice
shall not relieve either Party from its obligations under this Section 14.5,
except to the extent the other Party can establish actual prejudice and direct
damages as a result thereof. With respect to each Product Liability Claim
relating to Adolor Products, Adolor shall

                                      -93-

<PAGE>

assume the lead role in the defense of such Product Liability Claim and with
respect to each Product Liability Claim relating to GI Products, GSK shall
assume the lead role in the defense of such Product Liability Claim.

         14.5.3 The Party assuming the lead role shall consult with the other
Party on all material aspects of, and shall obtain the prior written consent of
the other Party (such consent not to be unreasonably withheld, refused,
conditioned or delayed) in respect of any material decisions to be taken with
regard to, the defense, including without limitation settlement of such Product
Liability Claim, and the other Party shall have a full opportunity to
participate in decision-making process with respect to the strategy of such
defense, and the Parties shall cooperate fully with each other in connection
therewith. The other Party shall also have the right to participate in the
defense of any Product Liability Claim utilizing attorneys of its choice, at its
own expense. In furtherance of the Parties' cooperation, the Party assuming the
lead role will consult with the other Party regarding strategic decisions,
including without limitation the retention of counsel and defense of each
Product Liability Claim. The Party assuming the lead role will otherwise keep
the other Party fully informed of the status and progress of the defense and any
settlement discussions concerning the Product Liability Claim.

     14.6  Insurance. Immediately upon First Commercial Sale, during the Term
           ---------
and for a period of five (5) years after the termination or expiration of this
Agreement, each Party shall obtain and/or maintain, respectively, at its sole
cost and expense, product liability insurance (including any self-insured
arrangements) in amounts, respectively, which are reasonable and customary in
the U.S. pharmaceutical industry for companies of comparable size and activities
at the respective place of business of each Party. Such product liability
insurance or self-insured arrangements shall insure against all liability,
including without limitation personal injury, physical injury, or property
damage arising out of the manufacture, sale, distribution, or marketing of the
Collaboration Products. Each Party shall provide written proof of the existence
of such insurance to the other Party upon request.

     14.7  Limitation of Liability. IN NO EVENT SHALL EITHER PARTY BE LIABLE TO
           -----------------------
THE OTHER OR ANY OF ITS AFFILIATES FOR ANY CONSEQUENTIAL, INCIDENTAL, INDIRECT,
SPECIAL, PUNITIVE OR EXEMPLARY DAMAGES (INCLUDING, WITHOUT LIMITATION, LOST
PROFITS, BUSINESS OR GOODWILL) SUFFERED OR INCURRED BY SUCH OTHER PARTY OR ITS
AFFILIATES IN CONNECTION WITH A BREACH OR ALLEGED BREACH OF THIS AGREEMENT. THE
FOREGOING SENTENCE SHALL NOT LIMIT THE OBLIGATIONS OF EITHER PARTY TO INDEMNIFY
THE OTHER PARTY FROM AND AGAINST THIRD PARTY CLAIMS UNDER THIS ARTICLE 14 OR
INFRINGEMENT CLAIMS UNDER SECTIONS 2.4.5(c), 2.4.8 AND 15.2.

                                      -94-

<PAGE>

                                   ARTICLE 15
                               PATENT INFRINGEMENT

     15.1  Prosecution and Maintenance of Patents.
           --------------------------------------

           15.1.1 Prosecution and Maintenance of Adolor Patents. Adolor shall
                  ---------------------------------------------
have the exclusive right and the obligation to (subject to Adolor's election not
to file, prosecute, or maintain pursuant to Section 15.1.4) or to cause its
licensors to, prepare, file, prosecute in a diligent manner (including without
limitation by conducting interferences, oppositions and reexaminations or other
similar proceedings), maintain (by timely paying all maintenance fees, renewal
fees, and other such fees and costs required under applicable Laws) and extend
all Adolor Patents and related applications. Adolor shall consult with GSK prior
to abandoning any Adolor Patents or related applications that are material to
the matters contemplated in this Agreement. Adolor shall regularly advise GSK of
the status of all pending applications, including with respect to any hearings
or other proceedings before any Governmental Authority, and, at GSK's request,
shall provide GSK with copies of all documentation concerning such applications,
including all correspondence to and from any Governmental Authority. Adolor
shall solicit GSK's advice and review of the nature and text of such patent
applications and important prosecution matters related thereto in reasonably
sufficient time prior to filing thereof, and Adolor shall take into account
GSK's reasonable comments related thereto.

          15.1.2 Prosecution and Maintenance of Patents Covering Joint
                 -----------------------------------------------------
Inventions.
----------

                 (a) For Patents covering Joint Inventions, the Parties shall
agree, without prejudice to ownership, which Party shall have the right to
prepare and file a priority patent application, and prosecute such
application(s) and maintain any patents derived therefrom, with the Parties
equally sharing the reasonable out-of-pocket costs for the preparation, filing,
prosecution and maintenance of such priority patent application. Should the
agreed upon Party elect not to prepare and/or file any such priority patent
application, it shall (i) provide the other Party with written notice as soon as
reasonably possible after making such election but in any event no later than
sixty (60) days before the other Party would be faced with a possible loss of
rights, (ii) give the other Party the right, at the other Party's discretion and
sole expense, to prepare and file the priority application(s), and (iii) offer
reasonable assistance in connection with such preparation and filing at no cost
to the other Party except for reimbursement of reasonable out-of-pocket expenses
incurred by the agreed upon Party in rendering such assistance. The other Party,
at its discretion and cost, shall prosecute such application(s) and maintain any
patents derived therefrom.

                 (b) Within nine (9) months after the filing date of a priority
application directed to an Invention, the Party filing the priority application
shall request that the other Party identify those non-priority ("foreign")

                                      -95-

<PAGE>

Countries in which the other Party desires that the Party filing the priority
application file corresponding patent applications. Within thirty (30) days
after receipt by the other Party of such request from the Party filing the
priority application, the other Party shall provide to the Party filing the
priority application a written list of such foreign countries in which the other
Party wishes to effect corresponding foreign patent applications filings.
Thereafter, within twelve (12) months after the filing date of the priority
application, the Party filing the priority application shall effect such
corresponding foreign filings in the countries selected by the other Party (the
filing in such foreign Country being hereinafter referred to as a "Designated
                                                                   ----------
Foreign Filing"). As to each Designated Foreign Filing, GSK shall bear the costs
--------------
for the filing and prosecutions of such Designated Foreign Filing. If GSK does
not request that an application be filed in a given foreign Country, and Adolor
nonetheless effects the filing of a patent application in this given Country,
then the costs for such filing and for maintaining such foreign application and
any patent issuing thereon shall be borne solely by Adolor. Should the Party
filing the priority application not agree to file or cause to be filed a
Designated Foreign Filing, the other Party will have the right to effect such
Designated Foreign Filing in its name at its own cost.

                 (c) Should the filing Party pursuant to Section 15.1.2(a) or
15.1.2(b) no longer wish to prosecute and/or maintain any patent application or
patent resulting from such application, the filing Party shall (i) provide the
non-filing Party with written notice of its wish no later than sixty (60) days
before the patent or patent applications would otherwise become abandoned, (ii)
give the non-filing Party the right, at the non-filing Party's election and sole
expense, to prosecute and/or maintain such patent or patent application, and
(iii) offer reasonable assistance to the non-filing Party in connection with
such prosecution and/or maintenance at not cost to the non-filing Party except
for reimbursement of the filing Party's reasonable out-of-pocket expenses
incurred by the filing Party in rendering such assistance.

                 (d) Should the non-filing Party pursuant to Section 15.1.2(c)
not wish to incur its share of preparation, filing, prosecution and/or
maintenance costs for a patent application filed pursuant to Section 15.1.2(a)
or 15.1.2(b) or patents derived therefrom, it shall (i) provide the filing Party
with written notice of its wish, and (ii) continue to offer reasonable
assistance to the filing Party in connection with such prosecution or
maintenance at no cost to the filing Party except for reimbursement of the
non-filing Party's reasonable out-of-pocket expenses incurred by the non-filing
Party in rendering such assistance.

                 (e) The Parties agree to cooperate in the preparation and
prosecution of all patent applications filed under Section 15.1.2(a) and
15.1.2(b), including obtaining and executing necessary powers of attorney and
assignments by

                                      -96-

<PAGE>

the named inventors, providing relevant technical reports to the filing Party
concerning the invention disclosed in such patent application, obtaining
execution of such other documents which shall be needed in the filing and
prosecution of such patent applications, and, as requested, updating each other
regarding the status of such patent applications.

          15.1.3 Prosecution and Maintenance of GSK Patents. GSK shall have the
                 ------------------------------------------
exclusive right and obligation to (subject to GSK's election not to file,
prosecute or maintain pursuant to Section 15.1.5) or to cause its licensors to,
prepare, file and prosecute in a diligent manner (including without limitation
by conducting interferences, oppositions and reexaminations or other similar
proceedings), maintain (by timely paying all maintenance fees, renewal fees, and
other such fees and costs required under applicable Laws) and extend all GSK
Patents and related applications. GSK shall consult with Adolor prior to
abandoning any GSK Patents or related applications that are material to the
matters contemplated in this Agreement. GSK shall regularly advise Adolor of the
status of all pending applications, including with respect to any hearings or
other proceedings before any Governmental Authority, and, at Adolor's request,
shall provide Adolor with copies of documentation relating to such applications,
including all correspondence to and from any Governmental Authority. GSK shall
solicit Adolor's advice and review of the nature and text of such patent
applications and important prosecution matters related thereto in reasonably
sufficient time prior to filing thereof, and GSK shall take into account
Adolor's reasonable comments related thereto.

          15.1.4 GSK Step-In Rights. If Adolor elects not to file, prosecute or
                 ------------------
maintain the Adolor Patents or claims encompassed by such Adolor Patents
necessary for GSK to exercise its rights hereunder in any Country, Adolor shall
give GSK notice thereof within a reasonable period prior to allowing such Adolor
Patents, or such claims encompassed by such Adolor Patents, to lapse or become
abandoned or unenforceable, and GSK shall thereafter have the right, at its sole
expense, to prepare, file, prosecute and maintain such Adolor Patents in such
Country.

          15.1.5 Adolor Step-In Rights. If GSK elects not to file, prosecute or
                 ---------------------
maintain the GSK Patents or claims encompassed by such GSK Patents necessary for
Adolor to exercise its rights hereunder in any Country, GSK shall give Adolor
notice thereof within a reasonable period prior to allowing such GSK Patents, or
such claims encompassed by such GSK Patents, to lapse or become abandoned or
unenforceable, and Adolor shall thereafter have the right, at its sole expense,
to prepare, file, prosecute and maintain such GSK Patents in such Country.

          15.1.6 Execution of Documents by Agents. Each of the Parties shall
                 --------------------------------
execute or have executed by its appropriate agents such documents as may be
necessary to obtain, perfect or maintain any Patent Rights filed or to be filed
pursuant to this Agreement, and shall cooperate with the other Party so far as
reasonably necessary with respect to furnishing all information and data in its
possession reasonably necessary to obtain or maintain such Patent Rights.

                                      -97-

<PAGE>

     15.2 Patent Infringement.
          -------------------

          15.2.1 Infringement Claims. With respect to any and all Claims
                 -------------------
instituted by Third Parties against Adolor or GSK or any of their respective
Affiliates for patent infringement involving the use, sale, license or marketing
of a Collaboration Product in the United States during the United States Term,
** (each, a "Patent Infringement Claim"), **, as applicable, and Adolor and GSK
             -------------------------
will assist one another and cooperate in the defense and settlement of such
Patent Infringement Claims at the other Party's request.

          15.2.2 Infringement of Adolor Patents. In the event that Adolor or GSK
                 ------------------------------
becomes aware of actual or threatened infringement of an Adolor Patent during
the Term, that Party will promptly notify the other Party in writing (a "Patent
                                                                         ------
Infringement Notice"). Subject to any Third Party rights existing as of the
-------------------
Effective Date and in accordance with the Lilly Agreement, Adolor will have the
right but not the obligation to bring an infringement action against any Third
Party. Adolor shall exercise this first right **. If Adolor elects to pursue
such infringement action, Adolor shall be solely responsible for the costs and
expenses associated with such action and retain all recoveries. During the Term
and subject to any Third Party rights existing as of the Effective Date, in the
event that Adolor does not undertake such an infringement action, upon Adolor's
written consent, which shall not be unreasonably withheld, refused, conditioned
or delayed, GSK shall be permitted to do so in Adolor's or the relevant Adolor
Affiliate's name and on Adolor's or the relevant Adolor Affiliate's behalf. If
Adolor has consented to an infringement action but GSK is not recognized by the
applicable court or other relevant body as having the requisite standing to
pursue such action, then GSK may join Adolor as party-plaintiff. If GSK elects
to pursue such infringement action, Adolor may **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -98-

<PAGE>

**

          15.2.3 Infringement of GSK Patents. In the event that GSK or Adolor
                 ---------------------------
becomes aware of actual or threatened infringement of a GSK Patent during the
United States Term, that Party will promptly notify the other Party in writing.
GSK will have the right but not the obligation to bring an infringement action
against any Third Party. GSK shall exercise this first right **. If GSK elects
to pursue such infringement action, GSK shall be solely responsible for the
costs and expenses associated with such action and retain all recoveries. During
the United States Term, in the event that GSK does not undertake such an
infringement action, upon GSK's written consent, which shall not be unreasonably
withheld, refused, conditioned or delayed, Adolor shall be permitted to do so in
GSK's or the relevant GSK Affiliate's name and on GSK's or the relevant GSK
Affiliate's behalf. If GSK has consented to an infringement action but Adolor is
not recognized by the applicable court or other relevant body as having the
requisite standing to pursue such action, then GSK may be joined as a
party-plaintiff. If Adolor elects to pursue such infringement action, GSK may
**.

    15.3 Notice of Certification. GSK and Adolor each shall immediately give
          -----------------------
notice to the other of any certification filed under the "U.S. Drug Price
Competition and Patent Term Restoration Act of 1984" (or its foreign equivalent)
claiming that a GSK Patent or an Adolor Patent is invalid or that infringement
will not arise from the manufacture, use or sale of any Collaboration Product by
a Third Party ("Hatch-Waxman Certification").
                --------------------------

          15.3.1 Notice. If a Party decides not to bring infringement
                 ------
proceedings against the entity making such a certification, such Party shall
give notice to the other Party of its decision not to bring suit within
twenty-one (21) days after receipt of notice of such certification.

          15.3.2 Option. Such other Party may then, but is not required to,
                 ------
bring suit against the entity that filed the certification.

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -99-

<PAGE>

          15.3.3 Name of Party. Any suit by Adolor or GSK shall either be in the
                 -------------
name of Adolor or in the name of GSK, or jointly in the name of Adolor and GSK,
as may be required by law.

     15.4 Assistance. For purposes of this Article 15, the Party not bringing
          ----------
suit shall execute such legal papers necessary for the prosecution of such suit
as may be reasonably requested by the Party bringing suit.

                                   ARTICLE 16
                              TERM AND TERMINATION

     16.1 Term. Unless otherwise mutually agreed to by the Parties, this
          ----
Agreement shall commence on the Effective Date and shall end with respect to the
United States, upon expiration of the United States Term, and with respect to
the ROW, upon expiration of the last to expire ROW Term, unless terminated
sooner as permitted hereunder.

     16.2 Extension of Adolor Product Promotion Term. If the Parties agree to
          ------------------------------------------
Develop the OBD Acute Product, or any Additional Product that becomes an Adolor
Product, the Adolor Product Promotion Term shall be extended until the sooner to
occur of (a) ** (**) years following the First Commercial Sale in the United
States of the OBD Acute Product or such Additional Product that is designated an
Adolor Product, or (b) ** (**) years after the First Commercial Sale of the POI
Product in the United States.

     16.3 Termination for Breach. Either Party may, without prejudice to any
          ----------------------
other remedies available to it at law or in equity, terminate this Agreement
with respect to the United States in the event that the other Party (as used in
this subsection, the "Breaching Party") shall have materially breached or
                      ---------------
defaulted in the performance of any of its obligations in the United States and
with respect to ** in the event that the Breaching Party shall have materially
breached or defaulted in the performance of its obligations in such **; provided
that if such material breach occurs in **, the non-breaching Party may also
terminate the **. The Breaching Party shall, if such breach can be cured, have
sixty (60) days after written notice thereof was provided to the Breaching Party
by the non-breaching Party to remedy such default (or, if such default cannot be
cured within such 60-day period, if the Breaching Party must commence and
diligently continue actions to cure such default during such 60-day period). Any
such termination shall become effective at the end of such 60-day period unless
the Breaching Party has cured any such breach or default prior to the expiration
of such 60-day period (or, if such default is capable of being cured but cannot
be cured within such 60-day period, the Breaching Party has commenced and
diligently continued actions to cure such default provided always that, in such
instance, such cure must have occurred within one hundred twenty (120) days
after written notice thereof was provided to the Breaching Party by the
non-breaching Party to remedy such default).

     16.4 Termination for Safety Related Reasons. GSK shall be entitled to
          --------------------------------------
terminate this Agreement, in whole or in part, by giving Adolor sixty (60) days
prior written notice if (a) GSK's internal Company Safety Board determines in
good faith, consistent with its decision making principles and policies as
applied to GSK's internally developed

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -100-

<PAGE>

products, to permanently cease all Development activities in respect of Compound
for one or more Collaboration Products due to an Adverse Drug Experience and/or
(ii) there are serious adverse events relating to Compound resulting in the
withdrawal of an Investigational Authorization or withdrawal of a Marketing
Authorization Approval of one or more Collaboration Products in the United
States.

     16.5 Termination by GSK with Respect to Adolor Products.
          --------------------------------------------------

          16.5.1  **.**

          16.5.2  **.**

          16.5.3  **.**

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -101-

<PAGE>

**

          16.5.4 **. **

     16.6 Termination by GSK with Respect to the OBD Chronic Product.
          ----------------------------------------------------------

          16.6.1 **. **

          16.6.2 **. **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -102-

<PAGE>

**
          16.6.3 **.

**

          16.6.4 **. **


     16.7 Termination by GSK With Respect to GI Products Other Than the OBD
          -----------------------------------------------------------------
Chronic Product.
---------------


          16.7.1 **. **


** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -103-

<PAGE>

          16.7.2 **.**


          16.7.3 **.**


     16.8 Termination by Adolor. On a Collaboration Product-by-Collaboration
          ---------------------
Product basis, Adolor shall be entitled to terminate this Agreement in the
following circumstances:

          16.8.1 Adolor Products in the ROW.
                 --------------------------

                 **

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -104-

<PAGE>

**

          16.8.2 **.**

          16.8.3 **.**

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -105-

<PAGE>

**

          16.8.4 **.**

          16.8.5 Delays in Supply of API Compound. In the event that GSK fails
                 --------------------------------
to achieve any of the timeline events set forth in this Section 16.8 or in the
U.S. Development Plan or ROW Development Plan, as applicable, due to a delay by
Adolor to supply API Compound necessary to achieve such timeline events, then
the timeline shall be extended by a period of time equal to the length of such
delay.

     16.9  Effects of Expiration of the Adolor Product Promotion Term. Upon the
           ----------------------------------------------------------
expiration of the Adolor Product Promotion Term, the following shall occur:

           16.9.1 Return of Materials. GSK shall promptly transfer to Adolor, at
                  -------------------
Adolor's cost, copies of all data, reports, records and materials for the United
States in its possession or control that relate to the Adolor Products and
return to Adolor, or destroy at Adolor's request, all relevant records and
materials in GSK's possession or control containing Confidential Information of
Adolor (provided that GSK may keep one copy of such Confidential Information of
Adolor for archival purposes only).

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -106-

<PAGE>

           16.9.2 Transfer of Regulatory Filings. GSK shall transfer to Adolor,
                  ------------------------------
at Adolor's cost, or shall cause its designee(s) to transfer to Adolor,
ownership of all regulatory filings made or filed for such Adolor Products for
the United States (to the extent that any are held in GSK's or such
designee(s)'s name), if permitted by applicable Laws and regulations.

           16.9.3 Return of GSK Confidential Information. Adolor shall promptly
                  --------------------------------------
return to GSK, at GSK's cost, or destroy at GSK's request all relevant records
and materials in Adolor's possession or control containing Confidential
Information of GSK for the United States relating to the Adolor Products
(provided that Adolor may keep one copy of such Confidential Information of GSK
for archival purposes only).

           16.9.4 License Rights. All licenses granted by Adolor to GSK with
                  --------------
respect to the Adolor Products under this Agreement for the United States shall
be terminated, except for any trademark or trade dress licenses if GSK is
utilizing such Adolor Product Trademark with a GI Product being Commercialized
in the United States or with a Collaboration Product being utilized in the ROW.

           16.9.5 GI Product Trademarks. In the event that Adolor is utilizing a
                  ---------------------
GI Product Trademark in connection with an Adolor Product being Commercialized
in the United States, Adolor shall receive a ** license to use such GI Product
Trademark solely in conjunction with such Adolor Products in the United States.

           16.9.6 Use of GSK Housemark and GSK Trade Dress. Adolor's right to
                  ----------------------------------------
use the GSK Housemark and GSK trade dress pursuant to Section 2.4.4(b) shall
survive expiration of the Adolor Product Promotion Term until such time as any
existing inventory of labeling, package inserts or outserts, monographs or
packaging materials or promotional materials for the Adolor Products in the
United States that contain the GSK Housemark or GSK trade dress have been
depleted, but in no event for longer than a period of ** (**) **.

     16.10 Effects of Expiration of the GI Product Promotion Term. Upon the
           ------------------------------------------------------
expiration of the GI Product Promotion Term, the following shall occur:

     16.10.1 Return of Confidential Information. Each Party, at its own cost,
             ----------------------------------
             shall promptly return to the other Party, or destroy at the
             Disclosing Party's request, all relevant records and materials in
             such Party's possession or control containing Confidential
             Information of the other Party for GI Products in the United
             States (provided that each Party may keep one copy of such
             Confidential Information of the other Party for archival purposes
             only).

     16.10.2 License Rights. The licenses granted by Adolor to GSK pursuant to
             --------------
             Section 2.1 with respect to the GI Products in the United States
             shall be considered fully-paid and royalty free and in the event
             that GSK is utilizing an Adolor Product Trademark in connection
             with a GI Product being Commercialized in the United States, GSK
             shall receive a ** license to use such Adolor

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -107-

<PAGE>

             Product Trademark solely in conjunction with such GI Products in
             the United States.

     16.10.3 Use of Adolor Housemark and Adolor Trade Dress. GSK's right to use
             ----------------------------------------------
             the Adolor Housemark and Adolor trade dress pursuant to Section
             2.4.4(a) shall survive expiration of the GI Product Promotion Term
             until such time as any existing inventory of labeling, package
             inserts or outserts, monographs or packaging materials or
             promotional materials for the GI Products in the United States that
             contain the Adolor Housemark or Adolor trade dress have been
             depleted, but in no event for longer than a period of ** (**) **.

     16.10.4 Assignment of GI Product Trademarks. In the event that GSK decides
             -----------------------------------
             to no longer Commercialize a GI Product in the United States, GSK
             shall assign any rights it may have in the GI Product Trademark in
             the United States to Adolor and Adolor shall pay to GSK a trademark
             royalty of ** percent (**%) on Net Sales of GI Products in the
             United States for so long as Adolor uses such assigned GI Product
             Trademark in the United States in conjunction with the sale of GI
             Products.

     16.11 Effects of Expiration of the ROW Term. Upon the expiration of the ROW
           -------------------------------------
Term, on a Collaboration Product-by-Collaboration Product and Country-by-Country
basis, the following shall occur:

     16.11.1 Return of Confidential Information. Each Party, at its own cost,
             ----------------------------------
             shall promptly return to the other Party, or destroy at the
             Disclosing Party's request, all relevant records and materials in
             such Party's possession or control containing Confidential
             Information of the other Party (provided that each Party may keep
             one copy of such Confidential Information of the other Party for
             archival purposes only).

     16.11.2 License Rights. The licenses granted by Adolor to GSK pursuant to
             --------------
             Section 2.1 with respect to the Collaboration Products in the ROW
             shall be considered **.

     16.11.3 Adolor Product Trademarks.
             -------------------------

                 (a)  GSK shall, at its own expense, assign to Adolor the
Adolor Products Trademarks which were used in connection with a Collaboration
Product in respect to those applicable Countries in the ROW in which GSK owns
the Adolor Product Trademarks in such Country. Upon such assignment, Adolor
shall grant GSK an exclusive license to use such Adolor Product Trademarks in
connection with such Collaboration Product in respect to those applicable
Countries in the ROW on the terms set forth in Section 16.11.3(b).

                 (b)  GSK shall pay Adolor a trademark royalty of ** percent
(**%) on Net Sales of Collaboration Products in the applicable Country of the
ROW for so long as GSK uses an Adolor Product Trademark in the ROW in

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -108-

<PAGE>

conjunction with the sale of Collaboration Products under the license granted in
Section 16.11.3(a).

     16.11.4 Use of Adolor Housemark or Adolor Trade Dress. GSK's right to use
             ---------------------------------------------
             the Adolor Product Trademark (having assigned the same to Adolor in
             accordance with the terms of this Agreement), the Adolor Housemark
             and the Adolor trade dress pursuant to Section 2.4.4(a) shall
             survive expiration of the ROW Term until such time as any existing
             inventory of labeling, package inserts or outserts, monographs or
             packaging materials or promotional materials for the Collaboration
             Products in the applicable Country of the ROW that contain the
             Adolor Housemark, the Adolor Product Trademarks or Adolor trade
             dress have been depleted, but in no event for longer than a period
             of ** (**) **.

     16.11.5 Assignment of ROW Trademarks. In the event that GSK decides to no
             ----------------------------
             longer Commercialize a Collaboration Product in the ROW, GSK shall
             assign, at Adolor's cost, any rights it may have in the GI Product
             Trademarks or ROW Trademarks, as applicable, to Adolor and Adolor
             shall pay to GSK a trademark royalty of ** percent (**%) on Net
             Sales of Collaboration Products in the ROW for so long as Adolor
             uses such assigned GI Product Trademark or ROW Trademark, as
             applicable, in the ROW in conjunction with the sale of
             Collaboration Products.

     16.12 Effect of Termination. On a Collaboration Product-by-Collaboration
           ---------------------
Product and/or on a ** and/or United States basis, in the event that this
Agreement is terminated (in which case such Collaboration Products so terminated
in such Major Region and/or the United States shall, for purposes of this
Section 16.12, be referred to as a "Terminated Collaboration Product"), the
                                    --------------------------------
following shall occur:

           16.12.1    Return of Materials. GSK shall, at its sole expense,
                      -------------------
promptly transfer to Adolor copies of all data, reports, records and materials
in its possession or control that relate to the Terminated Collaboration Product
and return to Adolor, or destroy at Adolor's request, all relevant records and
materials in its possession or control containing Confidential Information of
Adolor (provided that GSK may keep one copy of such Confidential Information of
Adolor for archival purposes only).

           16.12.2    Transfer of Regulatory Filings. GSK shall, at its sole
                      ------------------------------
expense, transfer to Adolor, or shall cause its designee(s) to transfer to
Adolor, ownership of all regulatory filings made or filed for the Terminated
Collaboration Product (to the extent that any are held in GSK's or such
designee(s)'s name), if permitted by applicable Laws and regulations.

          16.12.3     License Rights. Subject to Section 16.12.6, all licenses
                      --------------
granted by Adolor to GSK with respect to the applicable Terminated Collaboration
Product in the applicable ** under this Agreement shall be terminated.

          16.12.4     Assignment of Rights in the Adolor Product Trademarks, GI
                      ---------------------------------------------------------
Product Trademarks, ROW Trademarks and Promotional Material. GSK shall, at its
-----------------------------------------------------------
own expense,

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -109-

<PAGE>

assign to Adolor any rights it may have in the GI Product Trademarks and/or the
ROW Trademarks and corresponding promotional materials to the extent that the
foregoing relate to the Terminated Collaboration Product, and all such
trademarks and rights in the promotional materials shall be owned by Adolor. GSK
shall, at its own expense, assign to Adolor the Adolor Product Trademarks which
were used in connection with a Terminated Collaboration Product in respect of
those Countries in the ROW in which GSK owns the Adolor Product Trademarks.

          16.12.5     Manufacturing. For a Terminated Collaboration Product then
                      -------------
being manufactured by or on behalf of GSK, the Parties shall, at Adolor's sole
discretion, (a) negotiate, in good faith, a supply agreement for such Terminated
Collaboration Product on commercially reasonable terms, or (b) transfer any
required technology to Adolor or its designee to enable Adolor or such designee
to manufacture such Terminated Collaboration Product; provided that, in any
event, GSK shall ensure, for up to ** (**) **, that Adolor has a continuous
and uninterrupted supply of such Terminated Collaboration Product until such
supply agreement or transition is accomplished.

          16.12.6     Transfer of Inventory. Adolor shall be entitled to decide,
                      ---------------------
within its reasonably exercised discretion, whether (i) GSK shall sell to Adolor
or its designee at cost all remaining inventory of the Terminated Collaboration
Product which are in good saleable condition, or (ii) GSK shall be entitled to
sell out such remaining inventory under the conditions set forth in this
Agreement, including all payment obligations, during a period of six (6) months
after termination. Inventory of the Terminated Collaboration Product not sold to
Adolor or inventory not sold out by GSK shall be destroyed at GSK's sole cost
and expense. If Adolor decides to elect for item (ii) herein, GSK's rights to
use the Adolor Housemark pursuant to Section 2.4.4(b) and, to the extent
applicable, and, without prejudice to any other provision of this Agreement, the
GI Product Trademarks and the Adolor Product Trademarks shall survive
termination until expiry of such six (6) month period or, if earlier, until such
time as any existing inventory of labeling, package inserts or outserts,
monographs or packaging materials or promotional materials for the Terminated
Collaboration Product that contain the Adolor Housemark has been depleted.

          16.12.7     Transition During Notice Period. During the notice periods
                      -------------------------------
required pursuant to Section 16.5.1, 16.5.2, 16.5.4, 16.6.1, 16.6.2, 16.6.4,
16.7.2, 16.7.3 or 16.8, GSK shall be obligated to maintain its Commercially
Reasonable Efforts to Develop or Commercialize the Terminated Collaboration
Product in accordance with the applicable U.S. Marketing Plans and undertake all
reasonable efforts to transition any such activities to Adolor to enable Adolor
to continue the Development or Commercialization of the Terminated Collaboration
Product after such applicable notice period.

          16.12.8     Use of GSK Housemark or GSK Trade Dress. Adolor's right
                      ---------------------------------------
to use the GSK Housemark and GSK trade dress pursuant to Section 2.4.4(b) shall
survive termination until such time as any existing inventory of labeling,
package inserts

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -110-

<PAGE>

or outserts, monographs or packaging materials or promotional
materials for the Terminated Collaboration Product that contain the GSK
Housemark or GSK trade dress have been depleted, but in no event for longer than
a period of ** (**) **.

     16.13 Effect of Termination for Safety Related Reasons. In the event that
           ------------------------------------------------
GSK terminates this Agreement pursuant to Section 16.4, the Parties, in good
faith, shall cooperate and mutually agree as to the disposition of the
Collaboration Products.

     16.14 General Effects of Termination.
           ------------------------------

     16.14.1 Milestone Payments. GSK shall not be obligated to make a
             ------------------
             Development Milestone payment under Section 6.2 which is triggered
             by an event occurring after the effective date of termination of
             this Agreement.

           16.14.2  Accrued Rights; Surviving Obligations. Termination,
                    -------------------------------------
relinquishment or expiration of this Agreement for any reason shall be without
prejudice to any rights that shall have accrued to the benefit of any Party
prior to such termination, relinquishment or expiration. Such termination,
relinquishment or expiration shall not relieve any Party from obligations which
are expressly or by implication intended to survive termination, relinquishment
or expiration of this Agreement and shall not affect or prejudice any provision
of this Agreement which is expressly or by implication provided to come into
effect on, or continue in effect after, such termination, relinquishment or
expiration.

                                   ARTICLE 17
                  LIMITATIONS ON PURCHASES OF EQUITY SECURITIES

     17.1  Purchases of Equity Securities. During the Term and for a period of
           ------------------------------
one (1) year thereafter, except as permitted by Section 17.2, GSK and its
Affiliates will not (and will not assist or encourage others to) directly or
indirectly in any manner:

           17.1.1 acquire, or agree to acquire, directly or indirectly, alone or
in concert with others, by purchase, gift or otherwise, any direct or indirect
beneficial ownership (within the meaning of Rule l3d-3 under the Securities
Exchange Act of 1934, as amended (the "Exchange Act")) or interest in any
                                       ------------
securities or direct or indirect rights, warrants or options to acquire, or
securities convertible into or exchangeable for, any securities of Adolor;

           17.1.2 make, or in any way participate in, directly or indirectly,
alone or in concert with others, any "solicitation" of "proxies" to vote (as
such terms are used in the proxy rules of the Securities and Exchange Commission
(the "SEC") promulgated pursuant to Section 14 of the Exchange Act); provided,
      ---
however, that the prohibition in this Section 17.1.2 shall not apply to
solicitations exempted from the proxy solicitation rules by Rule 14a-2 under the
Exchange Act as such Rule 14a-2 is in effect as of the date hereof;

           17.1.3 form, join or in any way participate in a "group" within the
meaning of Section 13(d)(3) of the Exchange Act with respect to any voting
securities of Adolor;

**=Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                     -111-

<PAGE>

          17.1.4 acquire or agree to acquire, directly or indirectly, alone or
in concert with others, by purchase, exchange or otherwise, (i) any of the
assets, tangible or intangible, of Adolor or (ii) direct or indirect rights,
warrants or options to acquire any assets of Adolor, except for such assets as
are then being offered for sale by Adolor;

          17.1.5 enter into any arrangement or understanding with others to do
any of the actions restricted or prohibited under Sections 17.1.1, 17.1.2 or
17.1.3; or

          17.1.6 otherwise act in concert with others, to seek to offer to
Adolor or any of its stockholders any business combination, restructuring,
recapitalization or similar transaction to or with Adolor or otherwise seek in
concert with others, to control, change or influence the management, board of
directors or policies of Adolor or nominate any person as a director of Adolor
who is not nominated by the then incumbent directors, or propose any matter to
be voted upon by the stockholders of Adolor.

     17.2 Exceptions for Purchasing Securities of Adolor. Nothing herein shall
          ----------------------------------------------
prevent:

          17.2.1 GSK from purchasing additional equity security of Adolor if
after such purchase GSK and its Affiliates would own no greater percent of the
total voting power of all voting securities of Adolor then outstanding than GSK
owned immediately prior to the Effective Date.

          17.2.2 GSK from acquiring securities of Adolor issued in connection
with stock splits or recapitalizations or on exercise of pre-emptive rights
afforded to Adolor stockholders generally.

          17.2.3 GSK or GSK's employees from purchasing securities of Adolor
pursuant to (i) a pension plan established for the benefit of GSK's employees,
(ii) any employee benefit plan of GSK or (iii) any stock portfolios not
controlled by GSK or any of its Affiliates that invest in Adolor among other
companies.

          17.2.4 GSK from acquiring securities of another biotechnology or
pharmaceutical company that beneficially owns any of Adolor's securities.

          17.2.5 GSK or any of its Affiliates from acquiring equity securities
of Adolor without any limitation following initiation by a third party of an
unsolicited tender offer to purchase ** percent (**%) or more of any class or
service of Adolor's publicly traded voting securities (a "Hostile Tender
                                                          --------------
Offer"); provided that the exception provided by this Section 17.2.5 shall be
-----
limited to the classes or series of Adolor's securities that are the subject of
the Hostile Tender Offer; provided, further, that, in the event that either (a)
such Hostile Tender Offer is terminated or expires without the purchase of at
least ** percent (**%) of any class or series of Adolor's publicly traded voting
securities by such third party, or (b) the Adolor Board of Directors
subsequently recommends that such offer be accepted, then GSK shall divest in
one or more open-market transactions all shares of Adolor's securities so
acquired by it. Any such divestiture shall be completed as expeditiously as
possible consistent with applicable securities laws and

** = Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                      -112-

<PAGE>

regulations and in a manner intended to shield GSK from liability for recovery
of short swing profits under Section 16 of the Exchange Act and the rules
promulgated thereunder.

                                   ARTICLE 18
                                  MISCELLANEOUS

     18.1 Relationship of the Parties. Each Party shall bear its own costs
          ---------------------------
incurred in the performance of its obligations hereunder without charge or
expense to the other except as expressly provided in this Agreement. Neither
Party shall have any responsibility for the hiring, termination or compensation
of the other Party's employees or for any employee benefits of such employee. No
employee or representative of a Party shall have any authority to bind or
obligate the other Party to this Agreement for any sum or in any manner
whatsoever, or to create or impose any contractual or other liability on the
other Party without said Party's approval. For all purposes, and notwithstanding
any other provision of this Agreement to the contrary, GSK's legal relationship
under this Agreement to Adolor shall be that of independent contractor. This
Agreement is not a partnership agreement and nothing in this Agreement shall be
construed to establish a relationship of co-partners or joint venturers between
the Parties.

     18.2 Registration and Filing of this Agreement. To the extent, if any, that
          -----------------------------------------
either Party concludes in good faith that it or the other Party is required to
file or register this Agreement or a notification thereof with any Governmental
Authority, including without limitation the U.S. Securities and Exchange
Commission, the Competition Directorate of the Commission of the European
Communities or the U.S. Federal Trade Commission, in accordance with Law, such
Party shall inform the other Party thereof. Should both Parties jointly agree
that either of them is required to submit or obtain any such filing,
registration or notification, they shall cooperate, each at its own expense, in
such filing, registration or notification and shall execute all documents
reasonably required in connection therewith. In such filing, registration or
notification, the Parties shall request confidential treatment of sensitive
provisions of this Agreement, to the extent permitted by Law. The Parties shall
promptly inform each other as to the activities or inquiries of any such
Governmental Authority relating to this Agreement, and shall reasonably
cooperate to respond to any request for further information therefrom on a
timely basis.

     18.3 Force Majeure. The occurrence of an event which materially interferes
          -------------
with the ability of a Party to perform its obligations or duties hereunder which
is not within the reasonable control of the Party affected or any of its
Affiliates, not due to malfeasance by such Party or its Affiliates, and which
could not with the exercise of due diligence have been avoided (each, a "Force
                                                                         -----
Majeure Event"), including, but not limited to, an injunction, order or action
-------------
by a Governmental Authority, fire, accident, labor difficulty, strike, riot,
civil commotion, act of God, inability to obtain raw materials, delay or errors
by shipping companies or change in law, shall not excuse such Party from the
performance of its obligations or duties under this Agreement, but shall merely
suspend such performance during the continuation of the force majeure. The Party
prevented from performing its obligations or duties because of a Force Majeure
Event shall promptly notify the other Party of the occurrence and particulars of
such force majeure and shall provide the other

                                      -113-

<PAGE>

Party, from time to time, with its best estimate of the duration of such Force
Majeure Event and with notice of the termination thereof. The Party so affected
shall use Commercially Reasonable Efforts to avoid or remove such causes of
nonperformance as soon as is reasonably practicable. Upon termination of the
Force Majeure Event, the performance of any suspended obligation or duty shall
promptly recommence. The Party subject to the Force Majeure Event shall not be
liable to the other Party for any direct, indirect, consequential, incidental,
special, punitive, exemplary or other damages arising out of or relating to the
suspension or termination of any of its obligations or duties under this
Agreement by reason of the occurrence of a Force Majeure Event, provided such
Party complies in all material respects with its obligations under this Section
18.3.

     18.4 Governing Law. This Agreement shall be construed, and the respective
          -------------
rights of the Parties determined, according to the substantive law of the State
of Delaware notwithstanding the provisions governing conflict of laws under such
Delaware law to the contrary, except matters of intellectual property law which
shall be determined in accordance with the intellectual property laws relevant
to the intellectual property in question. The UNCITRAL Convention for the
International Sale of Goods, as well as any other unified law relating to the
conclusion and implementation of contracts for the international sale of goods,
shall not apply.

     18.5 Dispute Resolution; Arbitration.
          -------------------------------

          18.5.1 Dispute Resolution. For disputes not subject to Section 3.1.4,
                 ------------------
any dispute, controversy or claim arising out of or relating to this Agreement
which the Parties are unable to amicably settle themselves shall first be
submitted to the Joint Steering Committee for resolution. The Joint Steering
Committee shall have thirty (30) days to attempt to resolve the dispute and will
set forth any resolution in writing. If the Joint Steering Committee is unable
to resolve the dispute within the thirty (30) day period, the dispute shall
automatically be referred to the Officers within seventy-two (72) hours, and
such Officers shall attempt to resolve the dispute within a reasonable time, but
in no case more than forty-five (45) days from the time that the Joint Steering
Committee forwards its resolution to the Officers. The Officers shall issue
their resolution in writing.

          18.5.2 Arbitration. Any dispute, controversy or claim arising out of
                 -----------
or relating to this Agreement which the Parties have not resolved under Section
18.5.1, including, without limitation, disputes relating to (i) the validity,
inducement or breach of or the interpretation of any provision of this
Agreement, (ii) the interpretation or application of law or (iii) the ownership
of any intellectual property, shall be decided by arbitration in accordance with
the International Rules of the American Arbitration Association ("AAA") for
                                                                  ---
Commercial Arbitration in effect at the time the dispute arises, unless the
Parties hereto mutually agree otherwise. To the extent such rules are
inconsistent with this provision, this provision will control.

                 (a)  Any demand for arbitration must be made in writing to the
other Party.

                                      -114-

<PAGE>

                 (b)  There will be a panel of three arbitrators, one selected
by Adolor, one selected by GSK, and one selected by mutual agreement of the
arbitrators selected by Adolor and GSK. If the arbitrators selected by Adolor
and GSK cannot agree on a third arbitrator within thirty (30) days, then the AAA
shall select the third arbitrator. Any arbitration involving patent rights,
other intellectual property rights or intellectual property shall be heard by
arbitrators who are experts in such areas.

                 (c)  The arbitration shall be held in Wilmington, Delaware, or
such other place as the Parties agree. The arbitrators shall apply the
substantive law of Delaware in accordance with Section 18.4, without regard to
conflicts of laws and except that the interpretation and enforcement of this
arbitration provision shall be governed by the Federal Arbitration Act.

                 (d)  Neither Party shall have the right independently to seek
recourse from a court of law or other authorities in lieu of arbitration, but
each Party has the right before or during the arbitration to seek and obtain
from the appropriate court provisional remedies to avoid irreparable harm,
maintain the status quo or preserve the subject matter of the arbitration. There
shall be a stenographic record of the proceedings. The decision of the
arbitrators shall be made by majority vote and shall be final and binding upon
both Parties. The arbitrators shall render a written opinion setting forth
findings of fact and conclusions of law.

          18.5.3 Expenses of Arbitration. The expenses of the arbitration shall
                 -----------------------
be borne by the Parties in proportion as to which each Party prevails or is
defeated in arbitration. Each Party shall bear the expenses of its counsel and
other experts.

     18.6 Assignment. This Agreement may not be assigned by either Party without
          ----------
the prior consent of the other Party; provided, however that either Party may
assign this Agreement, in whole or in part, to any of its Affiliates if such
Party guarantees the performance of this Agreement by such Affiliate; and
provided further that either Party may assign this Agreement to a successor to
all or substantially all of the assets of such Party whether by merger, sale of
stock, sale of assets or other similar transaction. This Agreement shall be
binding upon, and subject to the terms of the foregoing sentence, inure to the
benefit of the Parties hereto, their permitted successors, legal representatives
and assigns.

     18.7 Notices. All demands, notices, consents, approvals, reports, requests
          -------
and other communications hereunder must be in writing and will be deemed to have
been duly given only if delivered personally, by facsimile with confirmation of
receipt, by mail (first class, postage prepaid), or by overnight delivery using
a globally-recognized carrier, to the Parties at the following addresses:

     Adolor:     Adolor Corporation
                 620 Pennsylvania Drive
                 Exton, Pennsylvania 19341
                 Facsimile: 484-595-1520
                 Attn: President

                                      -115-

<PAGE>

     With a copy to:       Morgan, Lewis & Bockius LLP
                           502 Carnegie Center
                           Princeton, NJ 08540
                           Attn: Randall B. Sunberg
                           Facsimile: 609-919-6639


     and with a copy to:   Dechert
                           4000 Bell Atlantic Tower
                           1717 Arch Street
                           Philadelphia, PA 19103
                           Attn: James A. Lebovitz
                           Facsimile: 215-994-2222

     GSK:   Glaxo Group Limited
            Glaxo Wellcome House
            Berkeley Avenue
            Greenford
            Middlesex
            UB6 0NN
            United Kingdom
            Attn:  Company Secretary
            Facsimile: 011 44 208-047-6912

     With a copy to:       GlaxoSmithKline plc
                           980 Great West Road
                           Brentford
                           Middlesex
                           TW8 9GS
                           United Kingdom
                           Attn: Corporate Law
                           Facsimile: 011 44 208-047-6912

     and with a copy to:   GlaxoSmithKline plc
                           980 Great West Road
                           Brentford
                           Middlesex
                           TW8 9GS
                           United Kingdom
                           Attn: Vice President, Worldwide Business Development
                           Facsimile: 011 44 208-990-8142

                                     -116-

<PAGE>

     or to such other address as the addressee shall have last furnished in
     writing in accord with this provision to the addressor. All notices shall
     be deemed effective upon receipt by the addressee.

     18.8 Severability. In the event of the invalidity of any provisions of this
          ------------
Agreement or if this Agreement contains any gaps, the Parties agree that such
invalidity or gap shall not affect the validity of the remaining provisions of
this Agreement. The Parties will replace an invalid provision or fill any gap
with valid provisions which most closely approximate the purpose and economic
effect of the invalid provision or, in case of a gap, the Parties' presumed
intentions. In the event that the terms and conditions of this Agreement are
materially altered as a result of the preceding sentences, the Parties shall
renegotiate the terms and conditions of this Agreement in order to resolve any
inequities. Nothing in this Agreement shall be interpreted so as to require
either Party to violate any applicable laws, rules or regulations.

       18.9  Headings. The headings used in this Agreement have been inserted
             --------
for convenience of reference only and do not define or limit the provisions
hereof.

       18.10 Waiver. Any term or condition of this Agreement may be waived at
             ------
any time by the Party that is entitled to the benefit thereof, but no such
waiver shall be effective unless set forth in a written instrument duly executed
by or on behalf of the Party waiving such term or condition. No waiver by any
Party of any term or condition of this Agreement, in any one or more instances,
shall be deemed to be or construed as a waiver of the same or any other term or
condition of this Agreement on any future occasion. Except as expressly set
forth in this Agreement, all rights and remedies available to a Party, whether
under this Agreement or afforded by law or otherwise, will be cumulative and not
in the alternative to any other rights or remedies that may be available to such
Party.

       18.11 Entire Agreement. This Agreement (including the exhibits and
             ----------------
schedules hereto) constitutes the entire agreement between the Parties hereto
with respect to the within subject matter and supersedes all previous agreements
and understandings between the Parties, whether written or oral. This Agreement
may be altered, amended or changed only by a writing making specific reference
to this Agreement and signed by duly authorized representatives of Adolor and
GSK.

       18.12 No License. Nothing in this Agreement shall be deemed to constitute
             ----------
the grant of any license or other right in either Party, to or in respect of any
Collaboration Product, patent, trademark, Confidential Information, trade secret
or other data or any other intellectual property of the other Party, except as
expressly set forth herein.

       18.13 Third Party Beneficiaries. None of the provisions of this Agreement
             -------------------------
shall be for the benefit of or enforceable by any Third Party, including without
limitation any creditor of either Party hereto. No such Third Party shall obtain
any right under any provision of this Agreement or shall by reasons of any such
provision make any Claim in respect of any debt, liability or obligation (or
otherwise) against either Party hereto.

                                      -117-

<PAGE>

       18.14 Counterparts. This Agreement may be executed in any two
             ------------
counterparts, each of which, when executed, shall be deemed to be an original
and both of which together shall constitute one and the same document.

                            [Signature Page Follows]

                                      -118-

<PAGE>

       IN WITNESS WHEREOF, Adolor and GSK, by their duly authorized officers,
have executed this Agreement as of the Effective Date.

ADOLOR CORPORATION                          GLAXO GROUP LIMITED



By:    /s/ John J. Farrar                   By:    /s/ J.P. Garnier
    -------------------------                  -----------------------------
       Name:  John J. Farrar                       Name:  J.P. Garnier
       Title: President and                        Title: Chief Executive
              Chief Executive                             Officer
              Officer


                    SIGNATURE PAGE TO COLLABORATION AGREEMENT

<PAGE>

                                  SCHEDULE 1.6
                                 ADOLOR PATENTS
                                       **

<PAGE>


                                  SCHEDULE 1.33
                                  COST OF GOODS


The cost of API Compound and/or a Collaboration Product manufactured by GSK
shall mean the **

<PAGE>

                                 SCHEDULE 1.113
                          POI CONTRACT PRODUCT PROFILE
                                       **

<PAGE>

                                 SCHEDULE 1.136
                                 TARGET AUDIENCE
                                       **

<PAGE>

                                 SCHEDULE 1.146
                       U.S. DEVELOPMENT PLANS FOR THE POI
                      PRODUCT AND THE OBD CHRONIC PRODUCT
                                       **

<PAGE>

                                 SCHEDULE 6.1
                          INVOICE FOR UPFRONT PAYMENT

<PAGE>

   [LOGO]
   adolor
CORPORATION

                                    INVOICE

420 Pennsylvania Drive   Glaxo Group Limited
       Exton, PA 19341

      494-595-1500 Tel                  **
      494-595-1520 Fax

                                        **

                         Pursuant to Section 6.1 of the Collaboration Agreement,
                         please remit to Adolor Corporation $50,000,000.00 U.S.
                         Dollars in immediately available funds via wire
                         transfer to:


                                        **

                         Payment Terms:
                         Payable within five (5) Business Days after the
                         Effective Date of the Collaboration Agreement.

                         Adolor contact:

                         Peter Schied
                         Chief Financial Officer
                         Tel: **

<PAGE>

                                  SCHEDULE 6.2
                               MILESTONE PAYMENTS
                                       **