Document:

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                                                                   EXHIBIT 10(p)

                                PLEDGE AGREEMENT

         THIS PLEDGE AGREEMENT ("Agreement") is made as of the 15th day of May,
2001, by Arabian American Development Company, a Delaware corporation, and
American Shield Refining Company, a Delaware corporation (hereinafter
collectively called "Pledgor", whether one or more), in favor of Fahad Al-Athel,
Hatem El-Khalidi, Ingrid El-Khalidi and Preston Peak (hereinafter collectively
called "Secured Party", whether one or more). Pledgor hereby agrees with Secured
Party as follows:

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

                  (a)      The term "Code" shall mean the Uniform Commercial
         Code as in effect in the State of Texas on the date of this Agreement
         or as it may hereafter be amended from time to time.

                  (b)      The term "Collateral" shall mean all property
         specifically described on Schedule "A" attached hereto and made a part
         hereof. The term Collateral, as used herein, shall also include (i) all
         certificates, instruments and/or other documents evidencing the
         foregoing, (ii) all renewals, replacements and substitutions of all of
         the foregoing, (iii) all Additional Property (as hereinafter defined),
         and (iv) all PRODUCTS and PROCEEDS of all of the foregoing. The
         designation of proceeds does not authorize Pledgor to sell, transfer or
         otherwise convey any of the foregoing property. The delivery at any
         time by Pledgor to Secured Party of any property as a pledge to secure
         payment or performance of any indebtedness or obligation whatsoever
         shall also constitute a pledge of such property as Collateral
         hereunder.

                  (c)      The term "Guaranty Documents" shall mean this
         Agreement, all documents and instruments evidencing all deferred
         compensation and retirement benefits owed by Pledgor to Hatem
         El-Khalidi and all letter agreements and other loan documents
         evidencing Indebtedness of Pledgor to Secured Party and all other
         instruments and documents evidencing, securing, governing, guaranteeing
         and/or pertaining to the Indebtedness, the aggregate principal amount
         of such Indebtedness as of the date hereof being as follows: Fahad
         Al-Athel, $445,000; Hatem El-Khalidi, $1,055,000; Ingrid El-Khalidi,
         $100,000; and Preston Peak, $100,000.

                  (d)      The term "Indebtedness" shall mean (i) all
         indebtedness, obligations and liabilities of Pledgor to Secured Party
         of any kind or character, now existing or hereafter arising, whether
         direct, indirect, related, unrelated, fixed, contingent, liquidated,
         unliquidated, joint, several or joint and several, now existing or
         hereafter arising under the Guaranty Documents, (ii) all accrued but
         unpaid interest on any of the indebtedness described in (i) above,
         (iii) all obligations of Pledgor to Secured Party under the Guaranty
         Documents or any documents evidencing, securing, governing and/or
         pertaining to all or any part of the indebtedness described in (i) and
         (ii) above, (iv) all costs and expenses incurred by Secured Party in
         connection with the collection and administration of all or any part of
         the indebtedness and obligations described in (i), (ii) and (iii) above
         or the protection or preservation of, or realization upon, the
         collateral securing all or any part of

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         such indebtedness and obligations, including, without limitation, all
         reasonable attorneys' fees and (v) all renewals, extensions,
         modifications and rearrangements of the indebtedness and obligations
         described in (i), (ii), (iii) and (iv) above.

                  (e)      The term "Secured Party" shall mean the persons named
         in the introductory paragraph of this Agreement, their respective
         successors and assigns, including, without limitation, any party to
         whom a Secured Party, or its successors or assigns, may assign its
         rights and interests under this Agreement.

All words and phrases used herein which are expressly defined in Section 1.201,
Chapter 8 or Chapter 9 of the Code shall have the meaning provided for therein.
Other words and phrases defined elsewhere in the Code shall have the meaning
specified therein, except to the extent such meaning is inconsistent with a
definition in Section 1.201, Chapter 8 or Chapter 9 of the Code.

         2.       SECURITY INTEREST. As security for the Indebtedness, Pledgor,
for value received, hereby grants to Secured Party a continuing security
interest in the Collateral.

         3.       ADDITIONAL PROPERTY. Collateral shall also include the
following property (collectively, the "Additional Property") which Pledgor
becomes entitled to receive or shall receive in connection with any other
Collateral: (a) any stock certificate, including, without limitation, any
certificate representing a stock dividend or any certificate in connection with
any recapitalization, reclassification, merger, consolidation, conversion, sale
of assets, combination of shares, stock split or spin-off; (b) any option,
warrant, subscription or right, whether as an addition to or in substitution of
any other Collateral; (c) any dividends or distributions of any kind whatsoever,
whether distributable in cash, stock or other property; (d) any interest,
premium or principal payments; and (e) any conversion or redemption proceeds. So
long as any Indebtedness shall remain outstanding, all rights of Pledgor to
receive and retain any dividends, distributions or interest paid in respect of
the Collateral shall cease and all such rights shall be vested in Secured Party,
who shall have the sole right to receive and hold as Collateral such dividends,
distributions and interest. All Additional Property received by Pledgor shall be
received in trust for the benefit of Secured Party and shall be segregated from
other funds and property of Pledgor. All Additional Property and all
certificates or other written instruments or documents evidencing and/or
representing the Additional Property that is received by Pledgor, together with
such instruments of transfer as Secured Party may request, shall immediately be
delivered to or deposited with Secured Party and held by Secured Party as
Collateral under the terms of this Agreement. If the Additional Property
received by Pledgor shall be shares of stock or other securities, such shares of
stock or other securities shall be duly endorsed in blank or accompanied by
proper instruments of transfer and assignment duly executed in blank with, if
requested by Secured Party, signatures guaranteed by a member or member
organization in good standing of an authorized Securities Transfer Agents
Medallion Program, all in form and substance satisfactory to Secured Party.
Secured Party shall be deemed to have possession of any Collateral in transit to
Secured Party or its agent.

         4.       VOTING RIGHTS. As long as no Event of Default shall have
occurred hereunder, any voting rights incident to any stock or other securities
pledged as Collateral may be exercised by Pledgor; provided, however, that
Pledgor will not exercise, or cause to be exercised, any such voting rights,
without the prior written consent of Secured Party, if the direct or indirect
effect of such vote will result in an Event of Default hereunder.

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         5.       MAINTENANCE OF COLLATERAL. Other than the exercise of
reasonable care to assure the safe custody of any Collateral in Secured Party's
possession from time to time, Secured Party does not have any obligation, duty
or responsibility with respect to the Collateral. Without limiting the
generality of the foregoing, Secured Party shall not have any obligation, duty
or responsibility to do any of the following: (a) ascertain any maturities,
calls, conversions, exchanges, offers, tenders or similar matters relating to
the Collateral or informing Pledgor with respect to any such matters; (b) fix,
preserve or exercise any right, privilege or option (whether conversion,
redemption or otherwise) with respect to the Collateral unless (i) Pledgor makes
written demand to Secured Party to do so, (ii) such written demand is received
by Secured Party in sufficient time to permit Secured Party to take the action
demanded in the ordinary course of its business, and (iii) Pledgor provides
additional collateral, acceptable to Secured Party in its sole discretion; (c)
collect any amounts payable in respect of the Collateral (Secured Party being
liable to account to Pledgor only for what Secured Party may actually receive or
collect thereon); (d) sell all or any portion of the Collateral to avoid market
loss; (e) sell all or any portion of the Collateral unless and until (i) Pledgor
makes written demand upon Secured Party to sell the Collateral, and (ii) Pledgor
provides additional collateral, acceptable to Secured Party in its sole
discretion; or (f) hold the Collateral for or on behalf of any party other than
Pledgor.

         6.       REPRESENTATIONS AND WARRANTIES. Pledgor hereby represents and
warrants the following to Secured Party:

                  (a)      Due Authorization. The execution, delivery and
         performance of this Agreement and all of the other Guaranty Documents
         by Pledgor have been duly authorized by all necessary corporate action
         of Pledgor, to the extent Pledgor is a corporation, or by all necessary
         partnership action, to the extent Pledgor is a partnership.

                  (b)      Enforceability. This Agreement and the other Guaranty
         Documents constitute legal, valid and binding obligations of Pledgor,
         enforceable in accordance with their respective terms, except as
         limited by bankruptcy, insolvency or similar laws of general
         application relating to the enforcement of creditors' rights and except
         to the extent specific remedies may generally be limited by equitable
         principles.

                  (c)      Ownership and Liens. Pledgor has good and marketable
         title to the Collateral, free and clear of all liens, security
         interests, encumbrances or adverse claims, except for the security
         interest created by this Agreement. No dispute, right of setoff,
         counterclaim or defense exists with respect to all or any part of the
         Collateral. Pledgor has not executed any other security agreement
         currently affecting the Collateral and no financing statement or other
         instrument similar in effect covering all or any part of the Collateral
         is on file in any recording office, except as may have been executed or
         filed in favor of Secured Party.

                  (d)      No Conflicts or Consents. Neither the ownership, the
         intended use of the Collateral by Pledgor, the grant of the security
         interest by Pledgor to Secured Party herein nor the exercise by Secured
         Party of its rights or remedies hereunder, will (i) conflict with any
         provision of (A) any domestic or foreign law, statute, rule or
         regulation, (B) the certificate of incorporation or bylaws of Pledgor
         or (C) any agreement, judgment, license, order or permit applicable to
         or binding upon Pledgor or otherwise affecting the Collateral or (ii)
         result in or require the creation of any lien, charge or encumbrance
         upon

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         any assets or properties of Pledgor or of any person except as may be
         expressly contemplated in the Guaranty Documents. Except as expressly
         contemplated in the Guaranty Documents, no consent, approval,
         authorization or order of, and no notice to or filing with, any court,
         governmental authority or third party is required in connection with
         the grant by Pledgor of the security interest herein or the exercise by
         Secured Party of its rights and remedies hereunder.

                  (e)      Security Interest. Pledgor has and will have at all
         times full right, power and authority to grant a security interest in
         the Collateral to Secured Party in the manner provided herein, free and
         clear of any lien, security interest or other charge or encumbrance.
         This Agreement creates a legal, valid and binding security interest in
         favor of Secured Party in the Collateral.

                  (f)      Location. Pledgor's residence or chief executive
         office, as the case may be, and the office where the records concerning
         the Collateral are kept is located at its address set forth on the
         signature page hereof.

                  (g)      Solvency of Pledgor. As of the date hereof, and after
         giving effect to this Agreement and the completion of all other
         transactions contemplated by Pledgor at the time of the execution of
         this Agreement, (i) Pledgor is and will be solvent, (ii) the fair
         saleable value of Pledgor's assets exceeds and will continue to exceed
         Pledgor's liabilities (both fixed and contingent), (iii) Pledgor is
         paying and will continue to be able to pay its debts as they mature and
         (iv) if Pledgor is not an individual, Pledgor has and will have
         sufficient capital to carry on Pledgor's businesses and all businesses
         in which Pledgor is about to engage.

                  (h)      Securities. Any certificates evidencing securities
         pledged as Collateral are valid and genuine and have not been altered.
         All securities pledged as Collateral have been duly authorized and
         validly issued, are fully paid and non-assessable, and were not issued
         in violation of the preemptive rights of any party or of any agreement
         by which Pledgor or the issuer thereof is bound. No restrictions or
         conditions exist with respect to the transfer or voting of any
         securities pledged as Collateral, except as has been disclosed to
         Secured Party in writing. To the best of Pledgor's knowledge, no issuer
         of such securities (other than securities of a class which are publicly
         traded) has any outstanding stock rights, rights to subscribe, options,
         warrants or convertible securities outstanding or any other rights
         outstanding entitling any party to have issued to such party capital
         stock of such issuer, except as has been disclosed to Secured Party in
         writing.

         7.       AFFIRMATIVE COVENANTS. Pledgor will comply with the covenants
contained in this Section at all times during the period of time this Agreement
is effective, unless Secured Party shall otherwise consent in writing.

                  (a)      Ownership and Liens. Pledgor will maintain good and
         marketable title to all Collateral, free and clear of all liens,
         security interests, encumbrances or adverse claims, except for the
         security interest created by this Agreement and the security interests
         and other encumbrances expressly permitted by the other Guaranty
         Documents. Pledgor will not permit any dispute, right of setoff,
         counterclaim or defense to exist with respect to all or any part of the
         Collateral. Pledgor will cause any financing statement or other

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         security instrument with respect to the Collateral to be terminated,
         except as may exist or as may have been filed in favor of Secured
         Party. Pledgor will defend at its expense Secured Party's right, title
         and security interest in and to the Collateral against the claims of
         any third party.

                  (b)      Inspection of Books and Records. Pledgor will keep
         adequate records concerning the Collateral and will permit Secured
         Party and all representatives and agents appointed by Secured Party to
         inspect Pledgor's books and records of or relating to the Collateral at
         any time during normal business hours, to make and take away
         photocopies, photographs and printouts thereof and to write down and
         record any such information.

                  (c)      Adverse Claim. Pledgor covenants and agrees to
         promptly notify Secured Party of any claim, action or proceeding
         affecting title to the Collateral, or any part thereof, or the security
         interest created hereunder and, at Pledgor's expense, defend Secured
         Party's security interest in the Collateral against the claims of any
         third party. Pledgor also covenants and agrees to promptly deliver to
         Secured Party a copy of all written notices received by Pledgor with
         respect to the Collateral, including, without limitation, notices
         received from the issuer of any securities pledged hereunder as
         Collateral.

                  (d)      Delivery of Instruments and/or Certificates.
         Contemporaneously herewith, Pledgor covenants and agrees to deliver to
         Secured Party any certificates, documents or instruments representing
         or evidencing the Collateral, with Pledgor's endorsement thereon and/or
         accompanied by proper instruments of transfer and assignment duly
         executed in blank with, if requested by Secured Party, signatures
         guaranteed by a member or member organization in good standing of an
         authorized Securities Transfer Agents Medallion Program, all in form
         and substance satisfactory to Secured Party.

                  (e)      Further Assurances. Pledgor will contemporaneously
         with the execution hereof and from time to time thereafter at its
         expense promptly execute and deliver all further instruments and
         documents and take all further action necessary or appropriate or that
         Secured Party may request in order (i) to perfect and protect the
         security interest created or purported to be created hereby and the
         first priority of such security interest, (ii) to enable Secured Party
         to exercise and enforce its rights and remedies hereunder in respect of
         the Collateral and (iii) to otherwise effect the purposes of this
         Agreement, including, without limitation: (A) executing and filing any
         financing or continuation statements, or any amendments thereto; (B)
         obtaining written confirmation from the issuer of any securities
         pledged as Collateral of the pledge of such securities, in form and
         substance satisfactory to Secured Party; (C) cooperating with Secured
         Party in registering the pledge of any securities pledged as Collateral
         with the issuer of such securities; (D) delivering notice of Secured
         Party's security interest in any securities pledged as Collateral to
         any securities or financial intermediary, clearing corporation or other
         party required by Secured Party, in form and substance satisfactory to
         Secured Party; and (E) obtaining written confirmation of the pledge of
         any securities constituting Collateral from any securities or financial
         intermediary, clearing corporation or other party required by Secured
         Party, in form and substance satisfactory to Secured Party. If all or
         any part of the Collateral is securities issued by an agency or
         department of the United States, Pledgor covenants and agrees, at
         Secured Party's request, to cooperate in registering such

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         securities in Secured Party's name or with Secured Party's account
         maintained with a Federal Reserve Bank. When applicable law provides
         more than one method of perfection of Secured Party's security interest
         in the Collateral, Secured Party may choose the method(s) to be used.

         8.       NEGATIVE COVENANTS. Pledgor will comply with the covenants
contained in this Section at all times during the period of time this Agreement
is effective, unless Secured Party shall otherwise consent in writing.

                  (a)      Transfer or Encumbrance. Pledgor will not (i) sell,
         assign (by operation of law or otherwise) or transfer Pledgor's rights
         in any of the Collateral, (ii) grant a lien or security interest in or
         execute, file or record any financing statement or other security
         instrument with respect to the Collateral to any party other than
         Secured Party or (iii) deliver actual or constructive possession of any
         certificate, instrument or document evidencing and/or representing any
         of the Collateral to any party other than Secured Party.

                  (b)      Impairment of Security Interest. Pledgor will not
         take or fail to take any action which would in any manner impair the
         value or enforceability of Secured Party's security interest in any
         Collateral.

                  (c)      Dilution of Ownership. As to any securities pledged
         as Collateral (other than securities of a class which are publicly
         traded), Pledgor will not consent to or approve of the issuance of (i)
         any additional shares of any class of securities of such issuer (unless
         immediately upon issuance additional securities are pledged and
         delivered to Secured Party pursuant to the terms hereof to the extent
         necessary to give Secured Party a security interest after such issuance
         in at least the same percentage of such issuer's outstanding securities
         as Secured Party had before such issuance), (ii) any instrument
         convertible voluntarily by the holder thereof or automatically upon the
         occurrence or non-occurrence of any event or condition into, or
         exchangeable for, any such securities or (iii) any warrants, options,
         contracts or other commitments entitling any third party to purchase or
         otherwise acquire any such securities.

                  (d)      Restrictions on Securities. Pledgor will not enter
         into any agreement creating, or otherwise permit to exist, any
         restriction or condition upon the transfer, voting or control of any
         securities pledged as Collateral, except as consented to in writing by
         Secured Party.

         9.       RIGHTS OF SECURED PARTY. Secured Party shall have the rights
contained in this Section at all times during the period of time this Agreement
is effective.

                  (a)      Power of Attorney. Pledgor hereby irrevocably
         appoints Secured Party as Pledgor's attorney-in-fact, such power of
         attorney being coupled with an interest, with full authority in the
         place and stead of Pledgor and in the name of Pledgor or otherwise, to
         take any action and to execute any instrument which Secured Party may
         from time to time in Secured Party's discretion deem necessary or
         appropriate to accomplish the purposes of this Agreement, including,
         without limitation, the following action: (i) transfer any securities,
         instruments, documents or certificates pledged as Collateral in the

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         name of Secured Party or its nominee; (ii) use any interest, premium or
         principal payments, conversion or redemption proceeds or other cash
         proceeds received in connection with any Collateral to reduce any of
         the Indebtedness; (iii) exchange any of the securities pledged as
         Collateral for any other property upon any merger, consolidation,
         reorganization, recapitalization or other readjustment of the issuer
         thereof, and, in connection therewith, to deposit and deliver any and
         all of such securities with any committee, depository, transfer agent,
         registrar or other designated agent upon such terms and conditions as
         Secured Party may deem necessary or appropriate; (iv) exercise or
         comply with any conversion, exchange, redemption, subscription or any
         other right, privilege or option pertaining to any securities pledged
         as Collateral; provided, however, except as provided herein, Secured
         Party shall not have a duty to exercise or comply with any such right,
         privilege or option (whether conversion, redemption or otherwise) and
         shall not be responsible for any delay or failure to do so; and (v)
         file any claims or take any action or institute any proceedings which
         Secured Party may deem necessary or appropriate for the collection
         and/or preservation of the Collateral or otherwise to enforce the
         rights of Secured Party with respect to the Collateral.

                  (b)      Performance by Secured Party. If Pledgor fails to
         perform any agreement or obligation provided herein, Secured Party may
         itself perform, or cause performance of, such agreement or obligation,
         and the expenses of Secured Party incurred in connection therewith
         shall be a part of the Indebtedness, secured by the Collateral and
         payable by Pledgor on demand.

Notwithstanding any other provision herein to the contrary, Secured Party does
not have any duty to exercise or continue to exercise any of the foregoing
rights and shall not be responsible for any failure to do so or for any delay in
doing so.

         10.      EVENTS OF DEFAULT. Each of the following constitutes an "Event
of Default" under this Agreement:

                  (a)      Failure to Pay Indebtedness. The failure, refusal or
         neglect of Pledgor to make any payment of principal or interest on the
         Indebtedness, or any portion thereof, as the same shall become due and
         payable; or

                  (b)      Non-Performance of Covenants. The failure of Pledgor
         to timely and properly observe, keep or perform any covenant,
         agreement, warranty or condition required herein or in any of the other
         Guaranty Documents; or

                  (c)      Default Under other Guaranty Documents. The
         occurrence of an event of default under any of the other Guaranty
         Documents.

                  (d)      False Representation. Any representation contained
         herein or in any of the other Guaranty Documents made by Pledgor is
         false or misleading in any material respect; or

                  (e)      Default to Third Party. The occurrence of any event
         which permits the acceleration of the maturity of any indebtedness
         owing by Pledgor to any third party under any agreement or undertaking;
         or

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                  (f)      Bankruptcy or Insolvency. If Pledgor: (i) becomes
         insolvent, or makes a transfer in fraud of creditors, or makes an
         assignment for the benefit of creditors, or admits in writing its
         inability to pay its debts as they become due; (ii) generally is not
         paying its debts as such debts become due; (iii) has a receiver,
         trustee or custodian appointed for, or take possession of, all or
         substantially all of the assets of such party or any of the Collateral,
         either in a proceeding brought by such party or in a proceeding brought
         against such party and such appointment is not discharged or such
         possession is not terminated within sixty (60) days after the effective
         date thereof or such party consents to or acquiesces in such
         appointment or possession; (iv) files a petition for relief under the
         United States Bankruptcy Code or any other present or future federal or
         state insolvency, bankruptcy or similar laws (all of the foregoing
         hereinafter collectively called "Applicable Bankruptcy Law") or an
         involuntary petition for relief is filed against such party under any
         Applicable Bankruptcy Law and such involuntary petition is not
         dismissed within sixty (60) days after the filing thereof, or an order
         for relief naming such party is entered under any Applicable Bankruptcy
         Law, or any composition, rearrangement, extension, reorganization or
         other relief of debtors now or hereafter existing is requested or
         consented to by such party; (v) fails to have discharged within a
         period of sixty (60) days any attachment, sequestration or similar writ
         levied upon any property of such party; or (vi) fails to pay within
         thirty (30) days any final money judgment against such party; or

                  (g)      Execution on Collateral. The Collateral or any
         portion thereof is taken on execution or other process of law in any
         action against Pledgor; or

                  (h)      Abandonment. Pledgor abandons the Collateral or any
         portion thereof; or

                  (i)      Action by Other Lienholder. The holder of any lien or
         security interest on any of the assets of Pledgor, including, without
         limitation, the Collateral (without hereby implying the consent of
         Secured Party to the existence or creation of any such lien or security
         interest on the Collateral), declares a default thereunder or
         institutes foreclosure or other proceedings for the enforcement of its
         remedies thereunder; or

                  (j)      Liquidation, Death and Related Events. If Pledgor is
         an entity, the liquidation, dissolution, merger or consolidation of any
         such entity or, if Pledgor is an individual, the death or legal
         incapacity of any such individual; or

                  (k)      Dilution of Ownership. The issuer of any securities
         (other than securities of a class which are publicly traded)
         constituting Collateral hereafter issues any shares of any class of
         capital stock (unless immediately upon issuance additional securities
         are pledged and delivered to Secured Party pursuant to the terms hereof
         to the extent necessary to give Secured Party a security interest after
         such issuance in at least the same percentage of such issuer's
         outstanding securities as Secured Party had before such issuance) or
         any options, warrants or other rights to purchase any such capital
         stock; or

                  (l)      Bankruptcy of Issuer. (i) The issuer of any
         securities constituting Collateral files a petition for relief under
         any Applicable Bankruptcy Law, (ii) an involuntary petition for relief
         is filed against any such issuer under any Applicable Bankruptcy Law
         and such involuntary petition is not dismissed within thirty (30) days

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         after the filing thereof or (iii) an order for relief naming any such
         issuer is entered under any Applicable Bankruptcy Law.

         11.      REMEDIES AND RELATED RIGHTS. If an Event of Default shall have
occurred, and without limiting any other rights and remedies provided herein,
under any of the other Guaranty Documents or otherwise available to Secured
Party, Secured Party may exercise one or more of the rights and remedies
provided in this Section.

                  (a)      Remedies. Secured Party may from time to time at its
         discretion, without limitation and without notice except as expressly
         provided in any of the Guaranty Documents:

                           (i)      exercise in respect of the Collateral all
                  the rights and remedies of a secured party under the Code
                  (whether or not the Code applies to the affected Collateral);

                           (ii)     reduce its claim to judgment or foreclose or
                  otherwise enforce, in whole or in part, the security interest
                  granted hereunder by any available judicial procedure;

                           (iii)    sell or otherwise dispose of, at its office,
                  on the premises of Pledgor or elsewhere, the Collateral, as a
                  unit or in parcels, by public or private proceedings, and by
                  way of one or more contracts (it being agreed that the sale or
                  other disposition of any part of the Collateral shall not
                  exhaust Secured Party's power of sale, but sales or other
                  dispositions may be made from time to time until all of the
                  Collateral has been sold or disposed of or until the
                  Indebtedness has been paid and performed in full), and at any
                  such sale or other disposition it shall not be necessary to
                  exhibit any of the Collateral;

                           (iv)     buy the Collateral, or any portion thereof,
                  at any public sale;

                           (v)      buy the Collateral, or any portion thereof,
                  at any private sale if the Collateral is of a type customarily
                  sold in a recognized market or is of a type which is the
                  subject of widely distributed standard price quotations;

                           (vi)     apply for the appointment of a receiver for
                  the Collateral, and Pledgor hereby consents to any such
                  appointment; and

                           (vii)    at its option, retain the Collateral in
                  satisfaction of the Indebtedness whenever the circumstances
                  are such that Secured Party is entitled to do so under the
                  Code or otherwise.

         Pledgor agrees that in the event Pledgor is entitled to receive any
         notice under the Uniform Commercial Code, as it exists in the state
         governing any such notice, of the sale or other disposition of any
         Collateral, reasonable notice shall be deemed given when such notice is
         deposited in a depository receptacle under the care and custody of the
         United States Postal Service, postage prepaid, at Pledgor's address set
         forth on the signature page hereof, five (5) days prior to the date of
         any public sale, or after which a private sale, of any of such
         Collateral is to be held. Secured Party shall not be obligated to make
         any sale of Collateral

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         regardless of notice of sale having been given. Secured Party may
         adjourn any public or private sale from time to time by announcement at
         the time and place fixed therefor, and such sale may, without further
         notice, be made at the time and place to which it was so adjourned.
         Pledgor further acknowledges and agrees that the redemption by Secured
         Party of any certificate of deposit pledged as Collateral shall be
         deemed to be a commercially reasonable disposition under Section
         9.504(c) of the Code.

                  (b)      Private Sale of Securities. Pledgor recognizes that
         Secured Party may be unable to effect a public sale of all or any part
         of the securities pledged as Collateral because of restrictions in
         applicable federal and state securities laws and that Secured Party
         may, therefore, determine to make one or more private sales of any such
         securities to a restricted group of purchasers who will be obligated to
         agree, among other things, to acquire such securities for their own
         account, for investment and not with a view to the distribution or
         resale thereof. Pledgor acknowledges that any such private sale may be
         at prices and other terms less favorable then what might have been
         obtained at a public sale and, notwithstanding the foregoing, agrees
         that each such private sale shall be deemed to have been made in a
         commercially reasonable manner and that Secured Party shall have no
         obligation to delay the sale of any such securities for the period of
         time necessary to permit the issuer to register such securities for
         public sale under any federal or state securities laws. Pledgor further
         acknowledges and agrees that any offer to sell such securities which
         has been made privately in the manner described above to not less than
         five (5) bona fide offers shall be deemed to involve a "public sale"
         for the purposes of Section 9.504(c) of the Code, notwithstanding that
         such sale may not constitute a "public offering" under any federal or
         state securities laws and that Secured Party may, in such event, bid
         for the purchase of such securities.

                  (c)      Application of Proceeds. If any Event of Default
         shall have occurred, Secured Party may at its discretion apply or use
         any cash held by Secured Party as Collateral, and any cash proceeds
         received by Secured Party in respect of any sale or other disposition
         of, collection from, or other realization upon, all or any part of the
         Collateral as follows in such order and manner as Secured Party may
         elect:

                           (i)      to the repayment or reimbursement of the
                  reasonable costs and expenses (including, without limitation,
                  reasonable attorneys' fees and expenses) incurred by Secured
                  Party in connection with (A) the administration of the
                  Guaranty Documents, (B) the custody, preservation, use or
                  operation of, or the sale of, collection from, or other
                  realization upon, the Collateral and (C) the exercise or
                  enforcement of any of the rights and remedies of Secured Party
                  hereunder;

                           (ii)     to the payment or other satisfaction of any
                  liens and other encumbrances upon the Collateral;

                           (iii)    to the satisfaction of the Indebtedness;

                           (iv)     by holding such cash and proceeds as
                  Collateral;

PLEDGE AGREEMENT - Page 10

<PAGE>

                           (v)      to the payment of any other amounts required
                  by applicable law (including, without limitation, Section
                  9.504(a)(3) of the Code or any other applicable statutory
                  provision); and

                           (vi)     by delivery to Pledgor or any other party
                  lawfully entitled to receive such cash or proceeds whether by
                  direction of a court of competent jurisdiction or otherwise.

                  (d)      Deficiency. In the event that the proceeds of any
         sale of, collection from, or other realization upon, all or any part of
         the Collateral by Secured Party are insufficient to pay all amounts to
         which Secured Party is legally entitled, Pledgor and any party who
         guaranteed or is otherwise obligated to pay all or any portion of the
         Indebtedness shall be liable for the deficiency, together with interest
         thereon as provided in the Guaranty Documents.

                  (e)      Non-Judicial Remedies. In granting to Secured Party
         the power to enforce its rights hereunder without prior judicial
         process or judicial hearing, Pledgor expressly waives, renounces and
         knowingly relinquishes any legal right which might otherwise require
         Secured Party to enforce its rights by judicial process. Pledgor
         recognizes and concedes that non-judicial remedies are consistent with
         the usage of trade, are responsive to commercial necessity and are the
         result of a bargain at arm's-length. Nothing herein is intended to
         prevent Secured Party or Pledgor from resorting to judicial process at
         either party's option.

                  (f)      Other Recourse. Pledgor waives any right to require
         Secured Party to proceed against any third party, exhaust any
         Collateral or other security for the Indebtedness, or to have any third
         party joined with Pledgor in any suit arising out of the Indebtedness
         or any of the Guaranty Documents, or pursue any other remedy available
         to Secured Party. Pledgor further waives any and all notice of
         acceptance of this Agreement and of the creation, modification,
         rearrangement, renewal or extension of the Indebtedness. Pledgor
         further waives any defense arising by reason of any disability or other
         defense of any third party or by reason of the cessation from any cause
         whatsoever of the liability of any third party. Until all of the
         Indebtedness shall have been paid in full, Pledgor shall have no right
         of subrogation and Pledgor waives the right to enforce any remedy which
         Secured Party has or may hereafter have against any third party, and
         waives any benefit of and any right to participate in any other
         security whatsoever now or hereafter held by Secured Party. Pledgor
         authorizes Secured Party, and without notice or demand and without any
         reservation of rights against Pledgor and without affecting Pledgor's
         liability hereunder or on the Indebtedness, to (i) take or hold any
         other property of any type from any third party as security for the
         Indebtedness, and exchange, enforce, waive and release any or all of
         such other property, (ii) apply such other property and direct the
         order or manner of sale thereof as Secured Party may in its discretion
         determine, (iii) renew, extend, accelerate, modify, compromise, settle
         or release any of the Indebtedness or other security for the
         Indebtedness, (iv) waive, enforce or modify any of the provisions of
         any of the Guaranty Documents executed by any third party, and (v)
         release or substitute any third party.

PLEDGE AGREEMENT - Page 11

<PAGE>

                  (g)      Voting Rights. Upon the occurrence of an Event of
         Default, Pledgor will not exercise any voting rights with respect to
         securities pledged as Collateral. Pledgor hereby irrevocably appoints
         Secured Party as Pledgor's attorney-in-fact (such power of attorney
         being coupled with an interest) and proxy to exercise any voting rights
         with respect to Pledgor's securities pledged as Collateral upon the
         occurrence of an Event of Default.

         12.      INDEMNITY. Pledgor hereby indemnifies and agrees to hold
harmless Secured Party, and its officers, directors, employees, agents and
representatives (each an "Indemnified Person") from and against any and all
liabilities, obligations, claims, losses, damages, penalties, actions,
judgments, suits, costs, expenses or disbursements of any kind or nature
(collectively, the "Claims") which may be imposed on, incurred by, or asserted
against, any Indemnified Person arising in connection with the Guaranty
Documents, the Indebtedness or the Collateral (including, without limitation,
the enforcement of the Guaranty Documents and the defense of any Indemnified
Person's actions and/or inactions in connection with the Guaranty Documents).
WITHOUT LIMITATION, THE FOREGOING INDEMNITIES SHALL APPLY TO EACH INDEMNIFIED
PERSON WITH RESPECT TO ANY CLAIMS WHICH IN WHOLE OR IN PART ARE CAUSED BY OR
ARISE OUT OF THE NEGLIGENCE OF SUCH AND/OR ANY OTHER INDEMNIFIED PERSON, except
to the limited extent the Claims against an Indemnified Person are proximately
caused by such Indemnified Person's gross negligence or willful misconduct. If
Pledgor or any third party ever alleges such gross negligence or willful
misconduct by any Indemnified Person, the indemnification provided for in this
Section shall nonetheless be paid upon demand, subject to later adjustment or
reimbursement, until such time as a court of competent jurisdiction enters a
final judgment as to the extent and effect of the alleged gross negligence or
willful misconduct. The indemnification provided for in this Section shall
survive the termination of this Agreement and shall extend and continue to
benefit each individual or entity who is or has at any time been an Indemnified
Person hereunder.

         13.      MISCELLANEOUS.

                  (a)      Entire Agreement. This Agreement contains the entire
         agreement of Secured Party and Pledgor with respect to the Collateral.
         If the parties hereto are parties to any prior agreement, either
         written or oral, relating to the Collateral, the terms of this
         Agreement shall amend and supersede the terms of such prior agreements
         as to transactions on or after the effective date of this Agreement,
         but all security agreements, financing statements, guaranties, other
         contracts and notices for the benefit of Secured Party shall continue
         in full force and effect to secure the Indebtedness unless Secured
         Party specifically releases its rights thereunder by separate release.

                  (b)      Amendment. No modification, consent or amendment of
         any provision of this Agreement or any of the other Guaranty Documents
         shall be valid or effective unless the same is in writing and signed by
         the party against whom it is sought to be enforced.

                  (c)      Actions by Secured Party. The lien, security interest
         and other security rights of Secured Party hereunder shall not be
         impaired by (i) any renewal, extension, increase or modification with
         respect to the Indebtedness, (ii) any surrender, compromise, release,
         renewal, extension, exchange or substitution which Secured Party may
         grant with respect to the Collateral or (iii) any release or indulgence
         granted to any endorser,

PLEDGE AGREEMENT - Page 12

<PAGE>

         guarantor or surety of the Indebtedness. The taking of additional
         security by Secured Party shall not release or impair the lien,
         security interest or other security rights of Secured Party hereunder
         or affect the obligations of Pledgor hereunder.

                  (d)      Waiver by Secured Party. Secured Party may waive any
         Event of Default without waiving any other prior or subsequent Event of
         Default. Secured Party may remedy any default without waiving the Event
         of Default remedied. Neither the failure by Secured Party to exercise,
         nor the delay by Secured Party in exercising, any right or remedy upon
         any Event of Default shall be construed as a waiver of such Event of
         Default or as a waiver of the right to exercise any such right or
         remedy at a later date. No single or partial exercise by Secured Party
         of any right or remedy hereunder shall exhaust the same or shall
         preclude any other or further exercise thereof, and every such right or
         remedy hereunder may be exercised at any time. No waiver of any
         provision hereof or consent to any departure by Pledgor therefrom shall
         be effective unless the same shall be in writing and signed by Secured
         Party and then such waiver or consent shall be effective only in the
         specific instances, for the purpose for which given and to the extent
         therein specified. No notice to or demand on Pledgor in any case shall
         of itself entitle Pledgor to any other or further notice or demand in
         similar or other circumstances.

                  (e)      Costs and Expenses. Pledgor will upon demand pay to
         Secured Party the amount of any and all costs and expenses (including,
         without limitation, attorneys' fees and expenses), which Secured Party
         may incur in connection with (i) the transactions which give rise to
         the Guaranty Documents, (ii) the preparation of this Agreement and the
         perfection and preservation of the security interests granted under the
         Guaranty Documents, (iii) the administration of the Guaranty Documents,
         (iv) the custody, preservation, use or operation of, or the sale of,
         collection from, or other realization upon, the Collateral, (v) the
         exercise or enforcement of any of the rights of Secured Party under the
         Guaranty Documents or (vi) the failure by Pledgor to perform or observe
         any of the provisions hereof.

                  (f)      GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY
         AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS AND
         APPLICABLE FEDERAL LAWS, EXCEPT TO THE EXTENT PERFECTION AND THE EFFECT
         OF PERFECTION OR NON-PERFECTION OF THE SECURITY INTEREST GRANTED
         HEREUNDER, IN RESPECT OF ANY PARTICULAR COLLATERAL, ARE GOVERNED BY THE
         LAWS OF A JURISDICTION OTHER THAN THE STATE OF TEXAS.

                  (g)      Venue. This Agreement has been entered into in Dallas
         County, Texas and it shall be performable for all purposes in such
         county. Courts within the State of Texas shall have jurisdiction over
         any and all disputes arising under or pertaining to this Agreement and
         venue for any such disputes shall be in the county or judicial district
         where this Agreement has been executed and delivered.

                  (h)      Severability. If any provision of this Agreement is
         held by a court of competent jurisdiction to be illegal, invalid or
         unenforceable under present or future laws, such provision shall be
         fully severable, shall not impair or invalidate the remainder of this

PLEDGE AGREEMENT - Page 13

<PAGE>

         Agreement and the effect thereof shall be confined to the provision
         held to be illegal, invalid or unenforceable.

                  (i)      Notices. All notices, requests, demands or other
         communications required or permitted to be given pursuant to this
         Agreement shall be in writing and given by (i) personal delivery, (ii)
         expedited delivery service with proof of delivery or (iii) United
         States mail, postage prepaid, registered or certified mail, return
         receipt requested, sent to the intended addressee at the address set
         forth on the signature page hereof or to such different address as the
         addressee shall have designated by written notice sent pursuant to the
         terms hereof and shall be deemed to have been received either, in the
         case of personal delivery, at the time of personal delivery, in the
         case of expedited delivery service, as of the date of first attempted
         delivery at the address and in the manner provided herein, or in the
         case of mail, upon deposit in a depository receptacle under the care
         and custody of the United States Postal Service. Either party shall
         have the right to change its address for notice hereunder to any other
         location within the continental United States by notice to the other
         party of such new address at least thirty (30) days prior to the
         effective date of such new address.

                  (j)      Binding Effect and Assignment. This Agreement (i)
         creates a continuing security interest in the Collateral, (ii) shall be
         binding on Pledgor and the heirs, executors, administrators, personal
         representatives, successors and assigns of Pledgor and (iii) shall
         inure to the benefit of Secured Party and the heirs, executors,
         administrators, personal representatives, successors and assigns of
         Secured Party. Without limiting the generality of the foregoing,
         Secured Party may pledge, assign or otherwise transfer the Indebtedness
         and its rights under this Agreement and any of the other Guaranty
         Documents to any other party. Pledgor's rights and obligations
         hereunder may not be assigned or otherwise transferred without the
         prior written consent of Secured Party.

                  (k)      Termination. Upon the satisfaction in full of the
         Indebtedness, this Agreement and the security interests created hereby
         shall terminate. Upon termination of this Agreement and Pledgor's
         written request, Secured Party will, at Pledgor's sole cost and
         expense, return to Pledgor such of the Collateral as shall not have
         been sold or otherwise disposed of or applied pursuant to the terms
         hereof and execute and deliver to Pledgor such documents as Pledgor
         shall reasonably request to evidence such termination.

                  (l)      Cumulative Rights. All rights and remedies of Secured
         Party hereunder are cumulative of each other and of every other right
         or remedy which Secured Party may otherwise have at law or in equity or
         under any of the other Guaranty Documents, and the exercise of one or
         more of such rights or remedies shall not prejudice or impair the
         concurrent or subsequent exercise of any other rights or remedies.

                  (m)      Gender and Number. Within this Agreement, words of
         any gender shall be held and construed to include the other gender, and
         words in the singular number shall be held and construed to include the
         plural and words in the plural number shall be held and construed to
         include the singular, unless in each instance the context requires
         otherwise.

PLEDGE AGREEMENT - Page 14

<PAGE>

                  (n)      Descriptive Headings. The headings in this Agreement
         are for convenience only and shall in no way enlarge, limit or define
         the scope or meaning of the various and several provisions hereof.

PLEDGE AGREEMENT - Page 15

<PAGE>

         EXECUTED as of the date first written above.

Pledgors' Addresses:                      ARABIAN AMERICAN DEVELOPMENT COMPANY
10830 North Central Expressway
Suite 175
Dallas, Texas 75231

                                          By:          /s/ J. A. Crichton
                                                   ---------------------------
                                          Name:        Jack Crichton
                                          Title:       Chairman

                                          AMERICAN SHIELD REFINING COMPANY

                                          By:          /s/ J. A. Crichton
                                                   ---------------------------
                                          Name:        Jack Crichton
                                          Title:       Chairman

Secured Parties Addresses:

10830 North Central Expressway
Suite 175
Dallas, Texas 75231

PLEDGE AGREEMENT - Page 16

<PAGE>

                                  SCHEDULE "A"

The following property is a part of the Collateral as defined in Subsection
1(b):

1.       All shares of stock in American Shield Refining Company, now existing
         and hereafter issued, presently evidenced by stock certificate no. 1,
         evidencing 100 shares of common stock.

2.       All shares of stock in Texas Oil and Chemical Co. II, Inc., now
         existing and hereafter issued, presently evidenced by stock certificate
         no. 13, evidencing 1,836,311 shares of common stock.

SCHEDULE A - Page 1<PAGE>

                                                                   EXHIBIT 10.14

          Confidential Materials omitted and filed separately with the
         Securities and Exchange Commission. Asterisks denote omissions.

CNRS No. 751272/03

                                                        UM2 N degrees: 03/CR/009

                              RESTATED AND AMENDED

                              COOPERATIVE AGREEMENT

                                     BETWEEN

IDENIX SARL (FORMERLY KNOWN AS NOVIRIO SARL),
Private Corporation whose headquarters is located at Immeuble "La Vigie" 170 rue
Leon Blum, 34000 Montpellier, trade registered in Montpellier under the No.
B419909148 in the corporate and trade register, REPRESENTED BY MR. JEAN-MARC
ALLAIRE, VICE PRESIDENT EUROPE,

acting in its name and in the name and on behalf of Idenix Pharmaceuticals,
Inc., (formerly known as Novirio Pharmaceuticals Limited), hereafter
collectively named IDENIX, represented by Mr. Jean-Pierre Sommadossi, Chairman
of the Board of Directors,

AND

LE CENTRE NATIONAL DE IN RECHERCHE SCIENTIFIQUE,
Public Institution for scientific and technological research, whose headquarters
is 3 rue Michel-Ange 75794, Paris, Cedex 16, France SIREN N degrees 180 089 013
; APE Code 732Z, REPRESENTED BY ITS DIRECTOR GENERAL, MADAME GENEVIEVE BERGER,
who grants a power of attorney to Mr. Michel RETOURNA, CNRS Regional Delegate
for the Languedoc-Roussillon Delegation to execute this Agreement,

                           hereafter named the "CNRS",

AND

L'UNIVERSITE MONTPELLIER II,
Public Institution with a cultural and professional vocation, located 2 place
Eugene Bataillon 34095 Montpellier Cedex 5, SIRET N degrees 193 410 883 00014,
APE Code 803Z REPRESENTED BY ITS PRESIDENT, MR. JACQUES BONNAFE,

                            hereafter named "UM II",

                                                                          Page 1

<PAGE>

Both the CNRS and the UM II, hereafter referred to as the Organization, acting
in their names and in the name and on behalf of the "Laboratoire de Chimie
Organique Biomoculeculaire de Synthese", UMR5625 of the CNRS, directed by Mr.
Gilles Gosselin,

                    hereafter referred to as the "LABORATORY"

The CNRS, the UM II and Idenix being collectively designated hereafter in this
document as "THE PARTIES",

AND

NOVARTIS PHARMA AG, a company registered under the laws of Switzerland, whose
headquarters are located Lichstrasse 35, 4056 Basel, Switzerland, REPRESENTED BY
MR. SUBBANU SAXENA, HEAD, BUSINESS DEVELOPMENT AND LICENSING-PRIMARY CARE, AND
BY MR. ROBERT PELZER, GENERAL COUNSEL

                       hereafter referred to as "NOVARTIS"

which is entering into this Agreement for limited purposes and is undertaking
only certain rights and obligations as provided in this Agreement.

Novartis is acting on its own behalf and on behalf of its Affiliates, with the
exception of IDENIX, hereafter referred to as "NOVARTIS AFFILIATES"; such
Affiliates being defined as any corporation, company, partnership, joint venture
and/or firm that controls, is controlled by, or is under common control with
Novartis. For purposes of this definition of "Affiliate", "control" shall mean
(a) in the case of corporate entities, direct or indirect ownership of at least
fifty percent (50%) of the stock or shares having the right to vote for the
election of directors, and (b) in the case of non-corporate entities, direct or
indirect ownership of at least fifty percent (50%) of the equity interest with
the power to direct the management and policies of such non-corporate entities.

WHEREAS, the Parties have entered into a Cooperative Laboratory Agreement
effective as of January 1, 1999 (CNRS Agreement # 751272/00), which has been
amended by supplemental Agreements dated May 17, 2001 (First Amendment #
751272/01) and April 11, 2002 (Second Amendment # 751272/02).

WHEREAS, the Parties have agreed to make additional amendments to the
Cooperative Laboratory Agreement.

WHEREAS, in addition, Idenix, certain stockholders of Idenix and Novartis have
entered into an agreement on March 21, 2003, under which Novartis has agreed to
acquire a majority equity interest in Idenix. Idenix and Novartis have further
agreed that they will enter into agreements to jointly develop and commercialize
Idenix's core antiviral drug candidates. In particular, Idenix and Novartis
expect to enter into an agreement relating to the development and
commercialization of certain products (hereafter the "DEVELOPMENT, LICENSE AND
COMMERCIALIZATION AGREEMENT") and an agreement relating to the manufacture and
supply of drug candidates and product (hereinafter the "Master Manufacturing and
Supply Agreement").

                                                                          Page 2

<PAGE>

As part of this cooperation, the Parties and Novartis have agreed that, after
execution and during the term of the Development, License and Commercialization
Agreement, Novartis and Novartis Affiliates would be expressly permitted to
exercise certain rights of Idenix under the Agreement as expressly provided in
this Agreement.

WHEREAS, the Parties now wish to amend and restate the Cooperative Laboratory
Agreement to incorporate the amendments agreed among them, and in particular,
the addition of Novartis as a limited party to the Agreement.

NOW, THEREFORE, the Parties agree to amend and restate the Cooperative
Laboratory Agreement as follows:

THE FOLLOWING IS AGREED TO:

ARTICLE 1. PURPOSE OF THE AGREEMENT

Together the Parties plan to conduct a research program and to allocate
material, financial, and human resources to it. The entity formed by the
research program and the means allocated to it is named the "cooperative
Laboratory of research on nucleosidic substances", hereafter designated as the
COOPERATIVE LABORATORY.

The purpose of this agreement is to define the operating methods of the
COOPERATIVE LABORATORY. It consists of a group of organizations whose aim is to
achieve a common goal, and does not imply in any way the creation of a legal
entity. It excludes the "affectio societatis" (intention to co-operate in a
partnership and right to supervise its administration*) and any other direct or
indirect association with any corporation in any form whatsoever. Specifically,
with regard to third parties, each of the Parties will act in its own name and
on its own behalf.

[*EDITOR'S NOTE: F.H.S. Bridge: The Council of Europe French-English Legal
Dictionary]

In addition, the purpose of this Agreement is to define the rights granted to
Novartis and Novartis Affiliates under this Agreement, as expressly and
exclusively provided in Articles 7 and 12 of this Agreement, and in Articles 1,
2, 3 and 4.3 of Annex 3 to this Agreement, and subject to the limitations set
forth in Article 12 of this Agreement.

ARTICLE 2. THE COOPERATIVE LABORATORY'S RESEARCH PROGRAM

This agreement applies to research directly or indirectly relating to the
discovery and development of nucleosidic and nucleotidic substances and of
analogs thereof to be used as therapeutic agents or for therapeutic applications
including but not limited to research and development of procedures, as well as
tests and methods related thereto, referred to as the RESEARCH FIELD hereafter.

Its purpose is to facilitate the activity of the Parties in research and
development for substances and methods that are relevant to the pharmaceutical
industry.

The COOPERATIVE LABORATORY's research program, referred to as the Research
Program hereafter, is defined annually. The initial Research Program is appended
to this agreement

                                                                          Page 3

<PAGE>

(Annex 1). It is updated every year and, if necessary, modified according to the
terms described in Article 5.1.2. In this case, Annex I shall be updated.

ARTICLE 3. MEANS ALLOCATED TO THE COOPERATIVE LABORATORY

3.1 COMPOSITION

The COOPERATIVE LABORATORY is comprised of personnel from the IDENIX
Laboratories, and from the CNRS and the UM II working full-tune or part-time in
the Research Program.

Temporary personnel may be added to the permanent personnel.

The permanent personnel is paid by and supervised by its original organization,
according to the terms described in Article 6.

3.2 LOCATION

The COOPERATIVE LABORATORY is located in premises provided by the UM II, as
described in Annex 2 to this Agreement, which is an integral part of this
Agreement. These premises constitute certain of the resources the UM II is
providing to the COOPERATIVE LABORATORY. Given the renovations done by Idenix
when it moved into the premises, the temporary authorization to use said
premises is given without additional financial cost. When use of the premises
shall cease, and at the latest upon termination of this Agreement, Idenix-shall
return such premises as they then exist.

3.3 MEANS

Each Party promises, for its part, to respect the plan for allocating resources
to the COOPERATIVE LABORATORY as described in Annex 2, which is an integral part
of this Agreement.

This Annex shall be updated every year following discussion between the Parties.

In addition to these planned resources, the Parties will strive to obtain
additional funding from different institutions likely to support the activities
of the COOPERATIVE LABORATORY.

In particular, the Organization will do everything it can to welcome foreign
researchers on long-term assignments with the COOPERATIVE LABORATORY.

ARTICLE 4. PARTNERSHIPS AND SIMILAR AGREEMENTS

Partners from the public or private sectors can be lead to collaborate in the
context of COOPERATIVE LABORATORY activities. Such collaboration will be the
subject of specific research projects signed by all of the Parties, and clauses
related to ownership and exploitation of results must be compatible with those
contained in this agreement. The present agreement shall prevail should there be
inconsistencies between this agreement and these specific contracts.

                                                                          Page 4

<PAGE>

ARTICLE 5. OPERATIONS

The definition and the implementation of the Research Program depend on the
powers of the Steering Committee and of the Director of the COOPERATIVE
LABORATORY, as indicated below.

5.1 STEERING COMMITTEE

5.1.1 COMPOSITION

The Steering Committee of the COOPERATIVE LABORATORY consists of two
representatives from the CNRS, of two representatives of the UM II, and of three
representatives for IDENIX, and of invited members. The Director of the
COOPERATIVE LABORATORY is entitled to participate to the Steering Committee. The
Steering Committee is made up as follows:

For IDENIX:

         -        The Vice President for Europe, IDENIX Laboratory (IDENIX
                  SARL), or his representative.

         -        The Chairman of the Board of Directors of IDENIX, and CEO of
                  IDENIX or his representative.

         -        Mr. Jean-Louis lmbach, Professor Emeritus of the University of
                  Montpellier 11, consultant for IDENIX Laboratories (IDENIX
                  SARL), or his representative.

For the CNRS:

         -        The Director of the Department of Chemistry at the CNRS, or
                  his representative.

         -        The Regional Delegate at the CNRS or his representative.

For UM II:

         -        The President of the Universite Montpellier II, or his
                  representative.

         -        An expert professor at the University Montpellier II,
                  designated by the President of the Universite Montpellier II,
                  or his representative.

In agreement with the other Parties, each Party can invite a person who is
renowned for his/her proficiency in the Research Field to join the Steering
Committee. This person will participate in the Steering Committee's meetings in
an advisory capacity.

Mr. JL lmbach will preside over the Steering Committee.

                                                                          Page 5

<PAGE>

5.1.2 POWERS

The Steering Committee's powers are the following:

-        To determine the orientation of the COOPERATIVE LABORATORY's research
         and to define the annual content of the Research Program or any
         potential changes. To prepare the annual update of Annex 1 described in
         Article 2.

-        To make an annual assessment of the means allocated to the COOPERATIVE
         LABORATORY and to prepare an advanced survey of the resources
         (personnel, financial resources, equipment) necessary for the Research
         Program for the following year.

-        To prepare a progress report on the COOPERATIVE LABORATORY's work and
         examine the results obtained.

-        To make an annual appraisal of the collaboration, and one year before
         the expiration of this Agreement, propose to the Parties its possible
         renewal, in conformity with Article 12 hereafter.

-        To decide matters within its competence related to publications and
         communications, in conformity with Article 8 hereafter.

-        In general terms, to ensure that the activities carried out are in
         compliance with the goals and provisions of this Agreement, and to
         settle important questions related to the smooth operation of the
         COOPERATIVE LABORATORY.

5.1.3 MEETINGS

The Steering Committee will meet at least once a year when notified by its
Chairman, who can also call a meeting at the request of one of the Parties.
Following each meeting, a report is drawn up and sent out to each member of the
Steering Committee.

5.2 DIRECTOR OF THE COOPERATIVE LABORATORY

The Director of the COOPERATIVE LABORATORY is appointed jointly by the Parties.
For the duration of this Agreement, as stipulated in Article 12, the Director is
Mr. Gilles Gosselin.

The Director is responsible for implementing the Research Program and managing
the resources allocated by the Parties to the COOPERATIVE LABORATORY.

He oversees the publication and communications projects involving the
COOPERATIVE LABORATORY's activities and is responsible for obtaining the
Parties' agreement on those projects, as stipulated in Article 8.

He ensures that the personnel involved in the COOPERATIVE LABORATORY's
activities respects the discipline and safety regulations, applicable on the
premises provided by the UM II.

                                                                          Page 6

<PAGE>

ARTICLE 6. PERSONNEL STATUS

The employees from each Patty taking part in the activities of the COOPERATIVE
LABORATORY retain their original status with their employer.

Each Party shall continue to assume all the legal, insurance, social security,
and tax obligations of the employer towards the employees on its payroll, to
ensure their coverage for accidents at work and occupational diseases, and to
apply to than all of the administrative prerogatives of management and staff. To
this end, each Party shall have at its disposal all necessary elements for
assessing its personnel.

Moreover, each Party provides third-party liability insurance for the actions of
its staff in the framework of the COOPERATIVE LABORATORY activities. It is
understood that each employee must comply with the discipline and safety
regulations in force at the UM II, the institution in which the activities of
the COOPERATIVE LABORATORY are carried out.

Personnel of the COOPERATIVE LABORATORY shall be authorized to access the
restaurants and the university library of the UM II. This access constitutes
certain of the resources the UM II is providing to the COOPERATIVE LABORATORY,
as defined in Annex 2 attached hereto.

Use of the shared services of the UM II (such as the common service Physical
Measurements, the reserve of solvents, the Glassworks service, the Fine Organic
Chemistry service [COF], etc.) by the COOPERATIVE LABORATORY shall be invoiced
by the relevant service pursuant to the internal tariff applicable at the date
of the order.

ARTICLE 7. CONFIDENTIALITY

Each Party promises not to publish, nor to use outside of the cooperation
framework, nor to disclose to a third party, in any way whatsoever, any
information which belongs to one or another of the Parties and which it could
have knowledge of as a result of contacts stemming from this Agreement.

Each Party promises to inform its permanent and temporary staff of the terms of
this Article and to ensure that this staff respects them.

This commitment remains effective as long as the information transmitted has not
become part of the public domain, and without any violation of any commitments
resulting from this article, this does not apply to information in cases where
the Party who received this information can prove that it had explicit
permission from the party concerned.

If in order to carry on its mission of creating economic value, one of the
Parties must disclose confidential information to a third party, this can be
done only after written agreement is obtained from the other Parties, specifying
the conditions of disclosure.

The Parties consider that for purposes of this Article 7, Novartis and Novartis
Affiliates shall not be considered as third parties to this Agreement, and shall
be considered as Parties to this Agreement. As a result, each Party shall be
authorized to disclose to Novartis and Novartis Affiliates any information which
belongs to one or another of the Parties, provided the disclosure

                                                                          Page 7

<PAGE>

of this information is materially necessary for Novartis to exercise its rights
under the Development, License and Commercialization Agreement and the Master
Manufacturing and Supply Agreement.

ARTICLE 8. PUBLICATIONS AND COMMUNICATIONS

The publications and communications relating to the COOPERATIVE LABORATORY's
activities are made by mutual agreement between the Parties involved and must
state the contribution made by each Party unless one of the parties explicitly
requests not to be mentioned.

Any reference to the personnel of the COOPERATIVE LABORATORY in articles,
abstracts, speeches or any other form of scientific communication shall contain
the following signature: "COOPERATIVE LABORATORY - IDENIX - University of
Montpellier II - CNRS".

The Director of the COOPERATIVE LABORATORY must obtain the consent of each Party
involved and they must reply within a maximum of [**] after this request. To
that end, each Party will designate a representative within the Steering
Committee responsible for evaluating publication or communications proposals and
for giving his consent in the name of the Party involved.

If no response is received within this time frame, the agreement is considered
to be implicit.

All communications or publications projects can be modified or have information
withheld when disclosure could harm industrial and commercial use of the results
of scientific studies.

In any event, no Party can withhold approval of publication or communication for
more than [**] after the request was made unless it has specified the strategic
nature of this information. In this event, the decision relating to the nature
and duration of the secret is made by the Steering Committee.

The provisions of this Article cannot constitute an obstacle:

-        to the obligation of researchers and teacher-researchers to produce an
         activity report for the organization they are employed by, as this
         communication does not constitute disclosure with respect to industrial
         property laws.

-        nor to presentations of theses of researchers whose scientific activity
         is related to this Agreement.

If necessary, researchers can provide a confidential activity report to the
Comite National de la Recherche Scientifique, to the Chairman of the CNRS
Standing Committee, and also to the President of the University of Montpellier
II. In the same way, theses' presentations can take place behind closed doors.

ARTICLE 9. INDUSTRIAL PROPERTY

                                                                          Page 8

<PAGE>

The CNRS who is responsible for creating economic value out of the work of the
Laboratory is mandated by the UM II to represent the Organization and act in its
name in the context of monitoring the economic value-creation of the COOPERATIVE
LABORATORY's activities.

9.1 RESULTS OBTAINED BY THE COOPERATIVE LABORATORY

Results obtained by the COOPERATIVE LABORATORY, within the framework of research
carried out under this Agreement, are owned jointly by the patties. Results
("Results") include, but are not limited to, technical information, laboratory
notebooks, data, trade secrets, know how, proprietary information and
inventions, documents and materials arising out of such research.

The Parties further agree that any and all rights, title and interest in the
technology, inventions, and/or discoveries directly or indirectly relating to
the subject matter of the patent applications U.S. application numbers [**] and
all continuations, divisionals, continuations-in-part, foreign counterparts, and
all other U.S. and international patent filings that claim priority to these
applications or to which these applications claim priority are deemed to be
included in the results obtained by the COOPERATIVE LABORATORY regardless of
whether the work was carried out prior to the formation of the COOPERATIVE
LABORATORY and regardless of the person or institution that carried out the
work. Such work specifically includes compositions, use and manufacture of [**]
for the treatment of [**]. The rules of co-ownership are defined in Annex 3 and
are an integral part of this Agreement.

9.2 RESULTS OBTAINED OUTSIDE OF THE COOPERATIVE LABORATORY

In the Research Field, as defined in Article 2, each Party retains ownership of
its own research and development activities conducted before the COOPERATIVE
LABORATORY was formed or outside of the Research Program conducted collectively
within the context of this Agreement.

An Owner Party may grant to others the right to use his knowledge at no cost in
order to carry out activities conducted within the context of the COOPERATIVE
LABORATORY.

The parties agree that results obtained outside of the Cooperative Laboratory as
defined in this Section do not include any and all rights, title and interest in
the technology, inventions, and/or discoveries directly or indirectly relating
to the subject matter of the patent applications U.S. application numbers [**]
and all continuations, divisionals, continuations-in-part, foreign counterparts,
and all other U.S. and international patent filings that claim priority to these
applications or to which these applications claim priority, which, by agreement
of Idenix and the Organization, are expressly deemed to fall under Article 9.1
as Results of the Cooperative Laboratory. The Parties further agree that
compositions, use and manufacture of [**] for the treatment of [**] fall under
Article 9.1 and not Article 9.2.

ARTICLE 10. EXPLOITATION OF RESULTS

For the purpose of this article, products and therapeutic procedures for [**]
created in the Research Field are defined and considered as being in the
Exploitation Field.

                                                                          Page 9

<PAGE>

10.1 MANAGING EXPLOITATION

The Parties promise to implement all possible means in order to exploit the
results obtained within the COOPERATIVE LABORATORY framework, whether or not
those results are patent-protected, co-owned, or are the subject of secret
technical files. For this, and subject to the provisions of Article 10.2 below,
they will either exploit them directly, or they will search for partners capable
of moving said results into the industrial stage, and will sign with these new
partners all necessary partnering agreements for licensing options, definitive
licenses or transfer of know-how.

10.2 EXPLOITING COOPERATIVE LABORATORY RESULTS

10.2.1 WITHIN THE EXPLOITATION FIELD

a) IDENIX has the exclusive world-wide right to exploit, directly or indirectly,
the Results obtained in the Exploitation Field within the framework of the
COOPERATIVE LABORATORY, which includes, without limitation, the right to make,
have made, use, sell, offer for sale and import the Results of the COOPERATIVE
LABORATORY in the Exploitation Field, either directly or indirectly, for all
commercial purposes, and the right to enter into license agreements and
collaborations on its own or through its affiliates with third parties to
authorize such third parties to make, use, sell, offer for sale and import said
Results for all commercial purposes, and IDENIX, agrees to pay a royalty to the
Organization under the conditions prescribed in Article 11.

b) IDENIX will ensure management of exploitation results within the Exploitation
Field, as stipulated in Article 10.1.

c) IDENIX is designated by the Organization to represent the Organization and
act in the name of the Organization, as part of the handling of the exploitation
of the Results, including, without limitation, entering into collaboration
and/or license agreements with third parties.

In this framework, IDENIX shall inform the Organization of any exploitation upon
conclusion of any agreement by registered letter with receipt requested.

In addition, in case of exploitation of the Results by a third party, IDENIX
shall transmit a copy of the contractual provisions pertaining to the Results
stipulated in the signed agreements to the Organization within a period not
exceeding four (4) months.

d) In the event that IDENIX foregoes exploiting the results in the context of
co-ownership, it is agreed that the Organization may, following IDENIX's written
consent, exploit those results instead of IDENIX. In this case, the Organization
will pass on to IDENIX a portion of the royalties it will collect, the
proportion to be determined case by case, under the conditions stipulated in a
signed agreement between the Parties.

10.2.2 OUTSIDE THE EXPLOITATION FIELD

Exploitation management as described in Article 10.1, will be ensured by the
Organization outside of the Exploitation Field. The Organization acting by order
of and on behalf of the

                                                                         Page 10

<PAGE>

Parties, will sign agreements with its new collaborators, provided that it has
previously received the written consent of IDENIX with respect to the
collaborator and the terms of the contract. IDENIX will not withhold its consent
without any legitimate motives. In the event of no response two months after the
request, the agreement will be deemed given.

The Organization will pass on to IDENIX a portion of the royalties it will
collect, the proportion to be determined case by case, under the conditions
stipulated in a signed agreement between the Parties.

10.3 EXPLOITATION OF THE LABORATORY RESULTS

10.3.1 WITHIN THE EXPLOITATION FIELD

In the case of results obtained by the Laboratory during this Agreement, outside
of the COOPERATIVE LABORATORY, within the Exploitation Field, IDENIX has
priority evaluation rights, for a period of [**], to consider direct
exploitation of those results. An exploitation agreement stipulating the royalty
conditions will have to be signed by all Owner Parties involved, before any
marketing initiative is made.

The Organization recognizes that the Laboratory does not and shall not be
subject to an agreement which prevents the Laboratory from acting in compliance
with the obligations defined in this Agreement.

10.3.2 OUTSIDE OF THE EXPLOITATION FIELD

In the case of results obtained by the Laboratory outside of the COOPERATIVE
LABORATORY, outside of the Exploitation Field, the Organization is totally free
to exploit the results without having to inform IDENIX of this or to pay IDENIX
any royalties.

ARTICLE 11. ROYALTIES FROM EXPLOITATION OF RESULTS BY IDENIX

In the event of direct or indirect commercial exploitation of the results,
IDENIX promises to pay a royalty to the Organization with a fixed rate of [**]%
on worldwide sales by IDENIX, its subsidiaries and its licensees of products
incorporating the Results, for the duration of this commercial exploitation. The
Parties will sign an agreement specifying the terms of the royalty payments
before any marketing initiative is made.

For purposes of this Article 11, IDENIX subsidiaries shall be defined as any
corporation, company, partnership, joint venture and/or firm that controls, is
controlled by, or is under common control with IDENIX; the notion of "control"
shall mean (a) in the case of corporate entities, direct or indirect ownership
of at least fifty percent (50%) of the stock or shares having the right to vote
for the election of directors, and (b) in the case of noncorporate entities,
direct or indirect ownership of at least fifty percent (50%) of the equity
interest with the power to direct the management and policies of such
non-corporate entities.

ARTICLE 12. DURATION - RENEWAL - CANCELLATION

                                                                         Page 11

<PAGE>

This agreement, which entered into force on the first of January 1999 for an
initial term of four (4) years, was amended and extended for an additional four
year term, to expire on December 31st 2006. Not less than one year before the
expiry of the agreement, the Steering Committee will gather to make an overall
assessment of the results of the collaboration and define the modalities whereby
this collaboration shall continue, in terms of scientific objectives and in
terms of resources. The Steering Committee will communicate its conclusions to
the Parties who will take the decision to stop or continue the collaboration at
the expiry of the term of the Agreement. In the latter case, a new agreement
shall be executed.

One of the Parties is entitled, by right of law, to terminate this Agreement in
the event of non-fulfillment by the other Party of one or more of the
obligations mentioned in this agreement. Termination shall only be effective
three months after the complaining party has sent a registered letter with
acknowledgement of receipt, specifying the reasons for the complaint, unless,
within this time frame, the defaulting party fulfils its obligations or proves
that this was a case of "force majeure".

Termination shall not exempt the defaulting party from fulfilling its
obligations contracted under this agreement prior to the effective time of
termination. In addition, the defaulting party shall be liable for any harm
suffered by the complaining party due to the early termination of this
agreement.

In cast of breach or default by Idenix under this Agreement, Novartis shall be
entitled to remedy such breach or default on behalf of Idenix. To this end, the
Parties shall provide Novartis with a copy of any notice of breach or default
delivered to Idenix, and any related correspondence, at the same time they are
delivered to Idenix.

Novartis shall inform the Parties of its decision to remedy Idenix's breach
within fifteen (15) business days following receipt by Novartis of the notice of
breach served to Idenix. If Novartis elects to remedy Idenix's breach,
termination shall only be effective if Novartis fails to remedy Idenix's breach
within three (3) months as of receipt by Novartis of the notice of breach served
to Idenix.

In the event that Novartis does not exercise its right to remedy such breach or
default on behalf of Idenix, and the other Parties become entitled to terminate
this Agreement as a result of Idenix's failure to remedy its breach, then prior
to the exercise of such right by the Parties, Novartis shall be entitled to
assume all of the rights and obligations of Idenix. The other Parties shall
accordingly notify Novartis in writing of their intention to terminate this
Agreement, and Novartis shall inform such Parties within fifteen (15) business
days as to whether it wishes to assume all the rights and obligations of Idenix
hereunder. If Novartis elects to assume such rights and obligations, it shall be
entitled to an additional fifteen (15) business day period to remedy the breach
or default giving rise to the right to terminate as set forth in this Article
12. Novartis shall succeed Idenix and assume all of Idenix's rights and
obligations hereunder upon, and without the need for any further action by any
Party hereunder other than, Novartis' timely remedy of the breach giving rise to
the termination event as set forth in this paragraph of Article 12.

                                                                         Page 12

<PAGE>

Each Party acknowledges and agrees that as of the date of execution of this
Restated and Amended Cooperative Agreement there is no breach or event of
default existing or continuing by any other Party.

The rights of Novartis provided in Articles 1, 2. 3 and 4.3 of Annex 3 to this
Agreement shall cease in case the Development, License and Commercialization
Agreement is terminated in whole or in part as a result of a breach by Novartis
of its obligations thereunder, or if the Development, License and
Commercialization Agreement is terminated by Novartis for convenience.

Notwithstanding expiration of the agreement, or its earlier termination:

         -        the provisions provided for in the "Confidentiality" article
                  remain in effect for the time periods stipulated in the
                  aforementioned article,

         -        the provisions provided for in the articles "Industrial
                  Propriety", "Exploitation of Results" and "IDENIX Exploitation
                  Royalties" remain in effect.

ARTICLE 13. LITIGATION AND DISPUTES

The Parties shall try to settle out of court all litigation and disputes that
could arise from the interpretation of this Agreement. In the case of persistent
disagreement, the case will be referred to the court of French competent
jurisdiction.

ARTICLE 14. LANGUAGE

This Agreement has been drafted in the English language and in the French
language. In case of contradiction between the two versions, the French version
shall prevail.

ARTICLE 15. COUNTERPART AND FACSIMILE SIGNATURES

Signatures provided by facsimile transmission shall be deemed to be original
signatures.

                                                 Drawn up in Montpellier on:

                                                 ____________________________
                                                 In five original copies
<TABLE>
<S>                           <C>                           <C>
For the Director General of   President of the University   For Idenix SARL and Idenix
the CNRS and on his           Montpellier II                Pharmaceuticals, Inc., The
authority, the Regional                                     Vice President for Europe of
Delegate                                                    Idenix

Michael RETOURNA              Jacques BONNAFE               Jean-Marc ALLAIRE

Novartis Pharma AG
As a limited party to this
Agreement
</TABLE>

                                                                         Page 13

<PAGE>

<TABLE>
<S>                           <C>                           <C>
Subhanu SAXENA, Head,
Business Development and
Licensing - Primary Care

Robert PELZER, General
Counsel
</TABLE>

                                                                         Page 14

<PAGE>

                                    ANNEX 1
                           SCIENTIFIC RESEARCH PROGRAM

The objective of the Scientific Research Program is to discover new nucleoside
and nucleotides and their analogs.

These new chemical compounds will have to be tested in order to define their
potential activity against [**].

The research program will consider [**].

Furthermore, there are plans to include in this program [**]There are plans to
[**].

When [**], plans are[**].

In these conditions, and only for the selected compounds, research into
improving [**] will be initiated.

                                                                         Page 15

<PAGE>

                                     ANNEX 2

                     RESOURCES OF THE COOPERATIVE LABORATORY

1 - PERSONNEL

1.1 WORK FORCE

1.1.1 CONTRIBUTION BY THE CNRS:

         -        A part-time Research Director: Dr. G. Gosselin,

         -        A part-time administrative technician: Mrs. MC Bergogne

1.1.2 CONTRIBUTION BY IDENIX

         -        seven Research Engineers and Laboratory Technicians,

         -        eleven laboratory technicians,

         -        two scholarships Doctor Engineer co-financed by the CNRS,

         -        a CIFRE Doctorate student,

         -        a part-time administrative assistant

In total, the contribution of IDENIX, in research personnel, can go up to 20
people.

1.2 PERSONNEL COST BASE

The cost basis for CNRS personnel is determined at the real salary cost, all
taxes included (including Doctoral Student Fellowship ("BDI")) without including
related administration costs.

The costs for University personnel correspond to the costs of the corresponding
categories.

The cost bases for the IDENIX Laboratories personnel are determined based on the
real cost of the employed personnel, including the administrative costs related
to the personnel, whose activity is devoted entirely to implementing the
Research Program.

1.3 FACILITIES

The COOPERATIVE LABORATORY has at its disposal a surface area of at least 200 m
located on the fourth floor of building 17, the chemistry annex and a surface
area of at least 170 m2 located on the ground floor of building 19.

Any modification of the facilities must be negotiated with the UM II, as needed
by the COOPERATIVE LABORATORY and shall be provided in an Annex to this
Agreement.

                                                                         Page 16

<PAGE>

The infrastructure costs of the COOPERATIVE LABORATORY are determined based on
the average cost per square meter of the University research facilities,
evaluated by the University at the time of execution of this Agreement and shall
be updated each year. Those costs are borne entirely by the UM II. In the
context of its contribution to the COOPERATIVE LABORATORY and in consideration
of the renovation work financed by IDENIX).

1.4 SCIENTIFIC EQUIPMENT AND OPERATIONS

The scientific equipment required for carrying out the Research Program will be
[**].

The operating costs of the COOPERATIVE LABORATORY (consumable goods, mission
costs) will be borne entirely by IDENIX.

Each year, IDENIX will deliver to the UM II a sum of [**]% of the costs for
consumable goods, to participate in the additional costs generated by the
research.

Schedule of payments:

In December of the current year, payment of a lump sum following assessment of
actual costs.

The applicable VAT rate shall be that in force on the date of payment of the
invoices.

Invoices shall be transmitted in two copies to IDENIX to the attention of Mr.
Jean-Marc Allaire.

The wire payment shall be made upon presentation of the invoice, in the name of
the Accounting Officer of the University of Montpellier II. on the account of
the General Treasury of Herault:

Account N degrees: [**]
Bank code: 10071
Branch code: 34000
Key: 65

                                                                         Page 17

<PAGE>

                                   SPREADSHEET

                 COOPERATIVE LABORATORY: ALLOCATION OF RESOURCES

                             FROM 1999 THROUGH 2002

                                       AND

                             FROM 2003 THROUGH 2006

                                                                         Page 18

<PAGE>

<TABLE>
<CAPTION>
                          1999              2000              2001              2002              Total                  REAL +
                       (in Euros)        (in Euros)        (in Euros)        (in Euros)        (in Euros HT)     REAL    BUDGET
                       ----------  ----  ----------  ----  ----------  ----  ----------  ----  -------------  ---------  -------
   Nature of costs       Budget    REAL    Budget    REAL   Budget     REAL    Budget*   REAL     Budget      1999-2001   2002
--------------------   ----------  ----  ----------  ----  ----------  ----  ----------  ----  -------------  ---------  -------
<S>                    <C>         <C>   <C>         <C>   <C>         <C>   <C>         <C>   <C>            <C>        <C>
           Personnel
                CNRS      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
               UM II      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
              IDENIX      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
          Facilities
  Infrastructure and
   environment costs
             (UM II)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
       Renovation of
reception facilities
             (UM II)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
      Renovation and
     modification to
conform to standards
            (Idenix)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
          Scientific
         environment
  Equipment (Idenix)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
    Consumable goods
            (Idenix)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
    Patents (Idenix)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]
       Mission costs
            (Idenix)      [**]     [**]     [**]     [**]     [**]     [**]     [**]               [**]         [**]      [**]

    Sub-total IDENIX      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]         [**]      [**]
     Sub-total UM II      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]         [**]      [**]
      Sub-total CNRS      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]         [**]      [**]
               TOTAL      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]         [**]      [**]
</TABLE>

Cooperative Laboratory, Allocation of resources    *revision following 3/29/2002

                                                                         Page 19
<PAGE>

<TABLE>
<CAPTION>
                          2003              2004              2005              2006              Total             REAL +
                       (in Euros)        (in Euros)        (in Euros)        (in Euros)        (in Euros HT)        BUDGET
  Nature of costs        Budget*   REAL    Budget*   REAL    Budget*   REAL   Budget*    REAL     Budget      REAL   N+1
-------------------    ----------  ----  ----------  ----  ----------  ----  ----------  ----  -------------  ----  ------
<S>                    <C>         <C>   <C>         <C>   <C>         <C>   <C>         <C>   <C>            <C>   <C>
           Personnel
                CNRS                                                                               [**]
               UM II                                                                               [**]
              IDENIX      [**]              [**]              [**]              [**]               [**]
          Facilities
  Infrastructure and
   environment costs
             (UM II)      [**]              [**]              [**]              [**]               [**]
       Renovation of
reception facilities
             (UM II)                                                                               [**]
      Renovation and
     modification to
conform to standards
            (Idenix)      [**]              [**]              [**]              [**]               [**]
          Scientific
         environment
  Equipment (Idenix)      [**]              [**]              [**]              [**]               [**]
    Consumable goods
            (Idenix)      [**]              [**]              [**]              [**]               [**]
    Patents (Idenix)      [**]              [**]              [**]              [**]               [**]
       Mission costs
            (Idenix)      [**]              [**]              [**]              [**]               [**]

    Sub-total IDENIX      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]       [**]   [**]
     Sub-total UM II      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]       [**]   [**]
      Sub-total CNRS      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]       [**]   [**]
               TOTAL      [**]     [**]     [**]     [**]     [**]     [**]     [**]     [**]      [**]       [**]   [**]
</TABLE>

Cooperative Laboratory, Allocation of resources  *revision following 3/29/2002

                                                                         Page 20
<PAGE>

                                     ANNEX 3

                             CO-OWNERSHIP SETTLEMENT
                        OF COOPERATIVE LABORATORY RESULTS

Any patents covering the Results obtained in the framework of the COOPERATIVE
LABORATORY will be filed in the names of the appropriate parties under the law
of the country of the patent filing, but will be exploited according to the
terms of this contract for the benefit of all of the Parties. Idenix (or
Novartis, as the case may be pursuant to Article 1.1 below) will assume all
costs for submitting a patent, for the patent being granted, for maintaining it,
and for defending it.

IDENIX (or Novartis, as the case may be the case pursuant to Article 1.1 below),
is designated by the Organization to represent the Organization and to act in
its name in all administrative procedures concerning Patents.

The co-ownership shares in patents attributed to each of the Parties will be
determined at the time of the patent's submission and will be based on the
intellectual and financial contributions of the Parties to the invention.

ARTICLE 1. SUBMISSION

1.1 VALUE ENHANCEMENT STRATEGY

During the execution of this agreement, each Party will promptly notify the
other Party in writing of the inventions made in the framework of the
COOPERATIVE LABORATORY.

IDENIX will evaluate the opportunity and the timing for submitting patents
protecting those inventions.

IDENIX will inform the Organization of its decision at the earliest opportunity.
The Parties agree that as may be agreed between Idenix and Novartis, Novartis
shall be entitled to act as Idenix's designee to submit a patent with Novartis
assuming all costs for submitting the patent. When IDENIX or Novartis decide not
to submit a patent, they will specify whether this decision is the result of a
wish to keep the invention secret or of disinterest in it. In the latter case,
the Organization will be able, if it deems this necessary, to proceed with the
submission in the conditions stipulated in Article 3 below.

1.2 SUBMISSION PROCEDURES

IDENIX will provide the Organization with the text of patent requests, and will
keep it informed of developments in the procedure.

The Organization promises to provide IDENIX with all the necessary materials,
technical or administrative, that IDENIX might need for the submission and
approval of patents.

IDENIX will choose the representative responsible for submitting the request and
shall provide such information to the Organization.

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The Parties promise that the name of the inventors will be mentioned in
agreement with the legal provisions in effect, in the patent requests.

The Parties are committed to ensuring that their employees, mentioned as
inventors, provide all the signatures and accomplish all the formalities
required for submission, approval, enforcement, and protection of the aforesaid
patents, in particular that they sign the assignment of rights in accordance
with the American procedure.

ARTICLE 2. CO-OWNERSHIP EXPLOITATION EXPENSES

IDENIX or Novartis as the case may be pursuant to Article 1.1 above, will cover
all of the administrative costs for patents.

ARTICLE 3. ABANDONMENT OF RIGHTS

If IDENIX or Novartis is not interested in submitting a patent, it will have to
notify, in a timely manner and in writing, the Organization that can then
proceed with the submission in its name and at its expense.

ARTICLE 4. INFRINGEMENT OF PATENT

4.1. The co-owners will inform each other mutually in the shortest time possible
of any instance of infringement of patent by third parties that they are aware
of and/or any claim or patent infringement action brought against them, and will
provide each other with all of the necessary elements at their disposal allowing
them to evaluate the nature and the impact of such.

4.2. If one of the Parties estimates that the observed infringement could
significantly impact the exploitation of one or more patents, it can consult the
other Party to discuss the most appropriate measures to end the infringement.

4.3. The Parties hereby grant IDENIX the first, full and sole right to enforce
or defend any patent obtained covering Results at IDENIX' sole expense, and the
Organization agrees to cooperate, assist, and participate in any litigation that
IDENIX deems necessary or desirable to defend such patents. In addition, the
Parties agree that as may be agreed between Idenix and Novartis, Novartis shall
be entitled to act as Idenix's designee to exercise Idenix's first right to
enforce or defend any patent obtained covering the Results with the costs of,
and any amount recovered or owed resulting from, any enforcement or defense
action or proceeding to be allocated between Novartis and IDENIX in accordance
with the Development, License and Commercialization Agreement. If IDENIX or
Novartis elects in writing not to defend or enforce a patent being infringed,
then the Organization is granted the second, full and sole right to enforce or
defend any patent obtained covering Results at the Organization's sole expense,
and then IDENIX agrees to cooperate, assist, and participate in any litigation
that the Organization deems necessary or desirable to defend such patents.

4.4. Subject to the provisions of Section 4.3 of this Article 4 above, any
damages awarded to the Parties by the courts will be shared between the Parties
in proportion to their participation in external expenses incurred to prosecute
the action successfully.

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4.5. If the Organization does not want to exercise the second right to enforce
the patent, either CNRS or UM II may individually take legal action at its own
expense, wherein IDENIX and the other party agree to cooperate, assist and
participate in any such litigation. In this case, all damages will be awarded to
the litigating party in full.

4.6. The Parties make a mutual commitment to provide all documents, powers, and
signatures to each other that they might need to undertake the legal actions in
accordance with the stipulations contained in all of the provisions of this
Article 4.

4.7. Subject to the provisions of Section 4.3 of this Article 4 above, if any
patent infringement actions were brought against one of the Parties for using
co-ownership Results, based on use of patents and/or of know-how obtained in the
framework of the COOPERATIVE LABORATORY, the other Parties will communicate
information they have for its defense. If the accused Party is condemned
following a patent infringement action, it will not implicate the other Parties.
In particular, it will refrain from calling another party in warranty
[impleading] and will not request any indemnity, nor refund of sums of any kind
already delivered to that party, nor any reduction in sums still owed at the
time of the final legal decision.

ARTICLE 5. ASSIGNMENT OF RIGHTS

Each co-owner can dispose of all or part of its co-ownership rights for patents
or patent requests and the corresponding secret technical files. The third Party
assignee will then be subrogated to the assignor in all rights and obligations
resulting from co-ownership of the securities under consideration.

Prior to any partial or total assignment of a co-ownership right, the assignor
Party must notify the other co-proprietor of its intention to assign its rights
in a registered letter mailed to the other co-owner, naming the potential third
Party assignee, and specifying the financial conditions of the assignment. In
this case, the other co-owners will benefit by virtue of a preemptive right to
financial conditions at least equal to those consented to the third Party. This
preemptive right will stand for a period of two months following notification.
At the end of this time, the assignor Party will benefit from the assignment
authorization automatically.

The right of notice and preemption prior to an assignment of patent or technical
rights does not apply in the case of the sale of all or substantially all of the
assets of the party, in which case the co-ownership right flows automatically
with the asset sale to the new owner of the assets. The new owner of all or
substantially all of the assets of the prior co owner must confirm in writing
its agreement to the co-ownership provisions set forth in this Agreement.

Provided the third Party assignee has confirmed previously in a registered
letter with acknowledgement of receipt, addressed to the co-owner who is not
assigning rights, his total support for the contents of the current co-ownership
regulations, the assignee will be subrogated by right of law to the assignor in
the rights and obligations provided for in the aforementioned regulations.

CNRS warrants and represents that it is the sole owner of all inventions,
conceptions, trade secrets, technical developments and patents of Dr. Gilles
Gosselin carried out or accomplished in

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the course of Dr. Gosselin's research and Results in the Cooperative
Laboratory. CNRS has not granted any rights held by the Cooperative Laboratory
to any other entity, and no government entity or other entity holds such rights
other than CNRS.

UM II warrants and represents that it is the sole owner of all inventions,
conceptions, trade secrets, technical developments and patents of Dr. Jean-Louis
Imbach carried out or accomplished in the course of Dr. Imbach's research and
Results in the Cooperative Laboratory. UM II has not granted any rights held by
the Cooperative Laboratory to any other entity, and no government entity holds
such rights other than UM II.

ARTICLE 6. DURATION OF CO-OWNERSHIP

All of these provisions will apply as long as the last intellectual property
rights subjected to co-ownership remain in force.

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