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                                                                   EXHIBIT 10.75

                  Agreement and Fourth Amendment (the "Agreement"), effective as
                                                       ---------
                  of February 13, 2002, by and among Incara Pharmaceuticals
                  Corporation, a Delaware corporation (the "Company"), Elan
                                                            -------
                  International Services, Ltd. ("EIS"), a Bermuda exempted
                                                 ---
                  limited liability company and a wholly owned subsidiary of
                  Elan Corporation, plc, an Irish public limited liability
                  company ("Elan"), Elan Pharma International Limited, an Irish
                            ----
                  private limited liability company and a wholly owned
                  subsidiary of Elan and an affiliate of EIS ("EPIL"), and Elan
                                                               ----
                  Pharmaceutical Investments III, Ltd., a Bermuda exempted
                  limited liability company ("EPIL III").
                                              --------
                  -------------------------------------------------------------

                                    RECITALS:

                  The Company, EIS and EPIL have entered into a Securities
Purchase Agreement dated as of December 21, 2000 (together with all amendments
prior to the date hereof, the "Purchase Agreement"), pursuant to which the
                               ------------------
Company issued and sold to EIS, and EIS purchased from the Company, (i) 12,015
shares of Series C Preferred Stock, par value US$0.01 per share, of the Company
(the "Series C Preferred Stock"), (ii) a warrant to purchase up to 22,191 shares
of Series B Preferred Stock, par value US$0.001 per share, the Company ("Series
B Preferred Stock"), (iii) 28,457 shares of Series B Preferred Stock and (iv)
825,000 shares of common stock, par value US$0.001 per share, of the Company
(the "Common Stock");

                  The Company, EIS and EPIL have entered into a Registration
Rights Agreement dated as of December 21, 2000 (together with all amendments
prior to the date hereof, the "Registration Rights Agreement"), pursuant to
                               -----------------------------
which the Company agreed, in certain circumstances as set forth in the
Registration Rights Agreement, to register with the Securities and Exchange
Commission any or all Registrable Securities held by a Holder;

                  On March 16, 2001, EIS has assigned to EPIL III, and EPIL III
assumed from EIS, (i) 12,015 shares of Series C Preferred Stock, (ii) the
warrant to purchase up to 22,191 shares of Series B Preferred Stock, (iii)
825,000 shares of Common Stock, (iv) 28,457 shares of Series B Preferred Stock
and (v) the rights of EIS under the Registration Rights Agreement with respect
to the shares of Common Stock underlying each of the securities so assigned;

                  The Company and EPIL have agreed to permit US$1,375,044.56 in
outstanding principal, together with all unpaid and accrued interest on such
principal, advanced or requested (in writing) to be advanced as of the date
hereof by EPIL to the Company pursuant to a certain Convertible Promissory Note,
dated December 21, 2000, issued by the Company to EPIL (the "Convertible Note"),
to be converted into shares of Common Stock and Series B Preferred Stock upon
the terms set forth herein; and

                  The parties desire to amend the Purchase Agreement and the
Registration Rights Agreement to modify the rights of EIS, EPIL and EPIL III and
their respective affiliates and

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transferees, as provided herein. Each term not otherwise defined herein shall
have the meaning ascribed to such term in the Purchase Agreement or the
Registration Rights Agreement, as the case may be.

                  In consideration of the foregoing premises and the mutual
covenants contained herein, the sufficiency of which is hereby acknowledged, the
parties hereby agree as follows:

         1.       Purchase Agreement Amendments. Subject to the conditions set
                  -----------------------------
forth herein, the Purchase Agreement is hereby amended as follows:

                  1.1    Section 1(f) of the Purchase Agreement (including all
         prior amendments to this section) is hereby replaced with the
         following:

                  "(f)   Second Closing. (A) Provided that the Initial Closing
                         --------------
         shall have occurred, upon the completion of enrollment of clinical
         trial OP201 for compound being developed by Newco or the Company, EIS
         shall, subject to obtaining any required approvals under the Mergers
         Acts, HSR Act, and any similar law and regulation, purchase shares of
         Series B Preferred Stock for an aggregate amount of either US$500,000
         or US$1,000,000, which amount shall be at the sole discretion of EIS
         (the "Second Purchase Price"), at a price per share equal to ten times
               ---------------------
         the greater of (1) 25% premium over the Average Daily Price for the 60
         trading day period immediately prior to the Later Date and (2) the
         Average Daily Price for the last trading day prior to the Later Date
         (the greater being the "Later Stock Price"). The term "Average Daily
                                 -----------------
         Price" shall mean the amount equal to the average of the highest and
         lowest trade price for Incara Common Stock on a given trading day. In
         addition, EIS shall purchase from the Company warrants to acquire
         shares of Series B Preferred Stock equal to 20% of the shares of Series
         B Preferred Stock purchased at the Second Closing, in the form attached
         hereto as Exhibit G (the "Later Incara Warrants"). Notwithstanding the
         above, in no event during the life of this Agreement shall the number
         of shares of Series B Preferred Stock purchased or underlying warrants
         issued in the Second Closing (it being understood that the warrants to
         be issued in the Second Closing shall be exercisable for a number of
         shares of Series B Preferred Stock equal to 20% of the number of shares
         of Series B Preferred Stock purchased in the Second Closing) exceed
         150,000 shares (as such number may be adjusted for stock splits,
         combinations, recapitalizations, reclassifications and dividends
         effected subsequent to December 21, 2000, the "Second Closing Maximum
                                                        ----------------------
         Shares"), which represents less than 20% of the Incara Common Stock
         ------
         issued and outstanding on December 21, 2000 (on an as converted basis).
         If this limitation on the amount of Series B Preferred Stock is
         triggered, the Second Purchase Price shall not be US$500,000 or
         US$1,000,000, as selected by EIS, but instead shall be equal to the
         Later Stock Price multiplied by the quotient of (i) the Second Closing
         Maximum Shares divided by (ii) 1.2, and the purchase of Series B
         Preferred Stock by EIS at the Second Closing shall be in the sole
         discretion of EIS. At the Second Closing (i) EIS shall pay the Second
         Purchase Price by wire transfer of the Second Purchase Price to an
         account designated in writing by the Company, (ii) the Company shall
         cause to be delivered to EIS (A) certificates representing the shares
         of Series B Preferred Stock issued to EIS, (B) the Later Incara
         Warrants, (C) a customary secretary's certificate from

                                        2

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         the secretary of the Company, including certification as to the
         incumbency of the officers of the Company executing any documents, (D)
         an officer's certificate certifying and confirming that the conditions
         described in Section 1(f)(B)(i)-(iii) below have been satisfied, (E) an
         opinion of counsel to the Company reasonably satisfactory to EIS, and
         (iii) either EIS or the Company shall deliver any other documents or
         instruments reasonably requested by a party hereto."

                  1.2   Section 5(b) of the Purchase Agreement is hereby amended
         by replacing the last sentence of Section 5(b) with the following:

                  "At all times that EIS or any of its Affiliates does not have
                  its own designee sitting on the Company's Board of Directors,
                  the Company shall use its best efforts to ensure that EIS or
                  such Affiliate of EIS (or their respective permitted
                  transferee or assignee) shall be entitled to appoint an
                  observer to attend each meeting of the Company's Board of
                  Directors (the "Board"), to receive notices of each meeting of
                  the Board (or action to be taken by written consent of the
                  Board) and to receive copies of all materials provided to all
                  members of the Board as a group. Such observer shall be
                  subject to the same confidentiality provisions as apply to any
                  director of EIS pursuant to Clause 21 of the Subscription,
                  Joint Development and Operating Agreement among Elan
                  Corporation, PLC, Elan Pharma International, Ltd., EIS and the
                  Company."

                  1.3   Section 16 of the Purchase Agreement is hereby amended
         by replacing the last sentence thereof with the following:

                  "Other than as set forth above, no party shall assign or
                  transfer all or any part of this Agreement, the Securities and
                  the Underlying Shares, or any interest therein, without the
                  prior written consent of the other party; provided that,
                  consent of the Company shall not be required in connection
                  with the sale, transfer or other disposition of any Securities
                  or the Underlying Shares in the event that such Securities or
                  the Underlying Shares are the subject of a registration
                  statement filed with the SEC or are eligible to be sold under
                  Rule 144 promulgated under the Securities Act, as such rule
                  may be amended from time to time, or any similar rule or
                  regulation hereafter adopted by the SEC."

         2.       Registration Rights Agreement Amendments. Subject to the
                  ----------------------------------------
conditions set forth herein, the Registration Rights Agreement is hereby amended
as follows:

                  2.1   Section 2(a) of the Registration Rights Agreement is
         hereby amended by deleting the fifth sentence of Section 2(a) (which
         stated "The Holders shall in the aggregate be permitted a total of one
         Demand Registration hereunder"), and replacing it in its entirety with
         the following sentence:

                                        3

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                  "The Holders shall in the aggregate be permitted a total of
                  two Demand Registrations hereunder."

         3.       Conversion of Outstanding Indebtedness.
                  --------------------------------------

                  3.1   Subject to the conditions set forth herein, EPIL hereby
         agrees to convert US$1,400,169.05 (which is comprised of
         US$1,375,044.56 in outstanding principal and US$25,124.49 in unpaid and
         accrued interest on such principal), due and owing under the
         Convertible Note (the "Outstanding Amount") into (i) 480,000 shares of
         Common Stock (determined by dividing US$628,800.00 by the lower of (a)
         the average closing sale price of the Common Stock as reported on the
         Nasdaq Market for the five trading days immediately prior to the date
         of this Agreement and (b) the closing sale price of the Common Stock as
         reported on the Nasdaq Market on the last trading day immediately prior
         to the date of this Agreement (the "Common Stock Conversion Price") and
         (ii) 58,883 shares of Series B Preferred Stock (determined by dividing
         US$771,369.05 by ten times the Common Stock Conversion Price).

                  3.2   The Company and EPIL agree that (i) this Section 3 shall
         constitute notice of conversion pursuant to Section 4(a) of the
         Convertible Note, (ii) the conversion of the Outstanding Amount shall
         occur prior to the date specified in the Convertible Note, (iii) the
         conversion price applicable to this conversion differs from Section
         4(a) of the Note, (iv) upon consummation of the conversion pursuant to
         this Section 3, the principal amount that may be advanced under the
         Note shall be reduced to US$3,430,955.44 and (v) other than as modified
         in connection with this conversion, the terms of the Convertible Note
         continue to be in force with respect to any additional advances made
         under the Convertible Note.

         4.      Restriction on Conversion of Certain Shares of Series B
                 -------------------------------------------------------
Preferred Stock. Each of EIS and EPIL hereby agrees that it shall not exercise
---------------
the right to convert into shares of Common Stock any share of Series B Preferred
Stock obtained by as a result of the conversion of the Note pursuant to Section
3 of this Agreement or as a result of the consummation of the second closing
contemplated by Section 1(f) of the Purchase Agreement, prior to the second
anniversary of the issuance by the Company of such share of Series B Preferred
Stock. Any assignment or transfer of such shares of Series B Preferred Stock by
EPIL or EIS shall be conditioned upon agreement by such transferee or assignee
to be bound by the restriction on conversion set forth herein.

         5.       Conditions to Obligations of EIS and EPIL. The obligations of
                  -----------------------------------------
each of EIS, EPIL and EPIL III under this Agreement are subject to the
satisfaction of the following conditions (or the waiver by EIS, EPIL and EPIL
III thereof in writing):

                  5.1   No material breach or default by the Company under any
         Transactions Document shall have occurred and be continuing; and

                  5.2   Except as set forth on Annex A attached hereto, the
                                               -------
         representations and warranties of the Company contained in Article 2 of
         the Purchase Agreement shall be true and correct in all material
         respects as of this Agreement.

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     6. Conditions to Obligations of the Company. The obligations of the Company
        ---------------------------------------- under this Agreement are
subject to the satisfaction of the following conditions (or the waiver by the
Company thereof in writing):

        6.1   The representations and warranties of EIS and EPIL contained in
     Article 3 of the Purchase Agreement shall be true and correct in all
     material respects as of the date of this Agreement.

     7. Amendment and Waiver. This Agreement may not be modified or amended, or
        -------------------- any of the provisions hereof waived, except by
written agreement of the Company,EIS, EPIL and EPIL III, dated after the date
hereof.

     8. Headings. The section and paragraph headings contained in this Agreement
        -------- are for reference purposes only and shall not affect in any way
the meaning or interpretation of the Agreement.

     9. Entire Agreement. This Agreement, the Subscription Agreement and the
        ---------------- Transaction Documents (as such Transaction Documents
have been amended prior to the date hereof) contain the entire understanding of
the parties with respect to the subject matter hereof and thereof and supersede
all prior agreements and understandings among the parties with respect thereto.
Other than as amended hereby, all Transaction Documents remain in full force and
effect.

     10. Governing Law. This Agreement shall be governed in all respects by the
         ------------- laws of the State of New York, without giving effect to
principles of conflicts of laws, and in accordance with the terms of Section 13
of the Purchase Agreement.

     11. Counterparts. This Agreement may be executed in any number of
         ------------ counterparts, including by facsimile signature, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     12. Expenses. Each of the parties shall be responsible for its own costs
         -------- and expenses incurred in connection with the transactions
contemplated hereby; provide that the Company shall indemnify EIS, EPIL, EPIL
III, their stockholders, officers, directors and assigns, their affiliates, and
their affiliates' stockholders, officers, directors, employees, agents,
representatives, successors and assigns (collectively, the "Indemnified
                                                            -----------
Person"), and save and hold each Indemnified Person harmless from and against
------ and pay on behalf of or reimburse each such Indemnified Person, as and
when incurred, for any and all costs and expenses (including attorneys' fees and
expenses) incurred by any Indemnified Person incurred or become subject to, as a
result of, in connection with, relating or incidental to or by virtue of, the
enforcement of the terms of this Agreement or the Transaction Documents to the
extent such documents have been amended hereby.

     13. Successors and Assigns. The provisions hereof shall inure to the
         ---------------------- benefit of, and be binding upon, the successors
and assigns of the parties hereto.

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     14. Severability. In case any provision of this Agreement shall be invalid,
         ------------ illegal or unenforceable, the validity, legality and
enforceabilityof the remaining provisions shall not be in any way affected or
impaired thereby.

                           [Signature Pages to Follow]
                           ---------------------------



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         In Witness Whereof, the parties have caused this Agreement to be
executed as of the date first above written.

                  Incara Pharmaceuticals Corporation

                  By:
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                  Name:
                       ---------------------------------------------------------

                  Title:
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                  Elan International Services, Ltd.

                  By:
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                  Name:
                       ---------------------------------------------------------

                  Title:
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                  Elan Pharma International Limited

                  By:
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                  Name:
                       ---------------------------------------------------------

                  Title:
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                  Elan Pharmaceutical Investments III, Ltd.

                  By:
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                  Name:
                       ---------------------------------------------------------

                  Title:
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