<PAGE>

                                                                   EXHIBIT 10.11

                                                                   [LOGO OF PII]

[CONFIDENTIAL TREATMENT HAS BEEN REQUESTED FOR THE PORTIONS OF THIS EXHIBIT
MARKED WITH ASTERIKS (***).]

                             Manufacturing Agreement

[CONFIDENTIAL TREATMENT HAS BEEN REQUESTED FOR INFORMATION REDACTED FROM THIS
PAGE.]

An agreement made on the 17th of March, 2000, between Pharmaceutics
International, Inc., of 10819 Gilroy Road, Suite 100, Hunt Valley, MD 21031
("PII") and Keryx Biopharmaceuticals, Inc., of 216 Jaffa Road, Jerusalem 94383
Israel ("Keryx"),

Whereas Keryx intends to commence clinical trials of its drug KRX-101 (also
known as sulodexide) *** contingent on FDA approval of its IND; and

Whereas Keryx requires the manufacture of the clinical trial materials ("CTM")
consisting of a certain number of gelcaps containing KRX-101, as well as gelcaps
containing a placebo, to conduct such clinical trials; and

Whereas PII has the necessary expertise to manufacture the gelcaps required by
Keryx.

It is hereby agreed by and between the parties:

1. Keryx's Responsibilities

        1.1.    Keryx shall be responsible for supplying PII with the following
                items:

                1.1.1.  API - Sulodexide
                1.1.2.  Technology transfer document including manufacturing
                        process
                1.1.3.  Cleaning Method
                1.1.4.  Material Safety Data Sheet
                1.1.5.  Packaging protocol

        1.2.    Keryx shall supply all special assays required for the drug
                substance (Factor Xa) and shall source an appropriate outside
                testing laboratory.

        1.3.    Keryx shall be responsible for all analytical method development
                (for drug product and drug substance) transfer.

2. PII's Responsibilities

        2.1.    Feasibility Batch

                2.1.1.  PII shall review the manufacturing protocol supplied by
                        Keryx.
                2.1.2.  PII shall purchase all excipients.
                2.1.3.  PII shall verify the cleaning method supplied by Keryx.
                2.1.4.  PII shall then manufacture a feasibility batch of
                        Sulodexide 50 mg and 100 mg of approximately ***
                        gelcaps of each strength to assess the manufacturing
                        parameters. The manufacture of the feasibility batch
                        shall be completed within two (2) weeks of the date on
                        which PII receives the Sulodexide material and the
                        technology transfer document including manufacturing
                        process.
<PAGE>

                                                                   [LOGO OF PII]

[CONFIDENTIAL TREATMENT HAS BEEN REQUESTED FOR INFORMATION REDACTED FROM THIS
PAGE.]

     2.2. Manufacture of the CTM

                2.2.1.  PII shall manufacture up to *** gelcaps of each of
                        the following:

                        .       Sulodexide - 50 mg
                        .       Sulodexide - 100 mg
                        .       Placebo - 50 mg
                        .       Placebo - 100 mg

                2.2.2.  PII shall accept all the excipients, active
                        pharmaceutical ingredients and packaging components with
                        vendor Certificate of Analysis and perform full testing
                        (4 - 6 weeks).
                2.2.3.  PII shall prepare Master Batch Records for the clinical
                        supplies.
                2.2.4.  The CTM shall be manufactured, packaged and labeled by
                        PII under cGMP conditions as directed by Keryx in the
                        manufacturing protocol. Manufacturing staff of PII shall
                        wear respirators and Tyvex suits if appropriate.
                2.2.5.  Packing component shall be HDPE bottles and blister
                        packs and shall be packaged by PII in accordance with
                        the Keryx protocol.
                2.2.6.  The following in-process and finished-product tests
                        shall be performed under cGMP condition on the CTM of
                        each strength or as mutually agreed upon by the parties:

                        .       Visual Inspection
                        .       Shell Hardness
                        .       Weight
                        .       Fill weight

                2.2.7.  The following in-process and finished-product tests
                        shall be performed on the placebo CTM or as mutually
                        agreed upon by the parties:

                        .       Visual Inspection
                        .       Absence of active ingredients
                        .       Hardness
                        .       Weight

                2.2.8.  PII does anticipate using contract laboratories for some
                        of the activities (for Microbiology testing) in this
                        Agreement. PII shall be responsible for ensuring, in
                        writing, that any contract lab used complied with Good
                        Laboratory Practices and with all other relevant
                        requirements set forth in the Agreement between PII and
                        Keryx.
                2.2.9.  Manufacturing and packaging of the CTM shall be
                        completed and the CTM delivered with all appropriate FDA
                        and cGMP requirement documentation, to Keryx or its
                        designee(s) within 4 weeks after full testing is
                        complete.

3. Quality Assurance

        3.1.    At least five (5) U.S. working days prior to the scheduled
                dispatch of each batch of finished gelcaps, PII shall send a
                sample of the batch to Keryx, or to a third party designated in
                writing by Keryx. Keryx shall have the sample tested by such
                third party to ID and release tests.
<PAGE>

[CONFIDENTIAL TREATMENT HAS BEEN REQUESTED FOR INFORMATION REDACTED FROM THIS
PAGE.]

                                                                   [LOGO OF PII]

        3.2.    If, after conducting such testing, a sample is determined to
                have failed to demonstrate the required activity, PII shall redo
                the entire batch of gelcaps, at its own expense, within seven
                (7) U.S. working days of its receipt of written notification by
                Keryx of the negative test.

4. Cost

        4.1.    The total cost of $ *** including packaging in HPDE bottles,
                shall be apportioned as follows:

<TABLE>
<CAPTION>
                       Activity                                  Cost
                       --------                                  ----
<S>           <C>                                              <C>
Section 2.1.3 Verification of Cleaning Method                   $ ***

Section 2.1.4 Feasibility Batches (50 mg/100 mg), Active and
              Placebo (4 batches in total)                      $ ***

Section 2.2.1 Clinical Trial Material Manufacturing:
              50 mg/100 mg 32,000 per batch                     $ ***

              Matching Placebos (4 batches in total)            $ ***

Section 2.2.5 Packaging in Bottles and Blister Packages            TBC

Section 3     General Support                                   $ ***
                                                               --------
Total                                                          $  ***
                                                               ========
</TABLE>


        4.2.    Payments are due fifteen (15) days from the date of each
                invoice, except for the first payment, which shall be due five
                (5) days from the date of the invoice. Amounts due shall be
                invoiced on the following schedule:

<TABLE>
<CAPTION>
Invoice Issue Date                                                    Amount Due
<S>             <C>                                                   <C>
      Day I     Initiation                                              $ ***
                Section 2.1.4 Completion of feasibility batches         $ ***
                Section 2.2.3 Completion of CTM batch records           $ ***
                Section 2.2.9 Release of batches                        $ ***
                                                                       --------
Total                                                                  $  ***
                                                                       ========
</TABLE>

        4.3.    In addition to the above costs, Keryx shall pay to PII upon
                receipt of PII's invoice by Keryx for all non-capital materials
                (excipients, packaging components, HPLC columns, analytical
                standards and tooling, if any) used in the study at ***. PII
                shall obtain Keryx's prior written approval for any expenditures
                greater than $5,000. For high priced items more than $5,000, PII
                shall charge *** to Keryx, PII shall invoice Keryx for all
                reasonable and normal out-of pocket travel related expenses,
                including airfare, room & board, car rental and the like, of PII
                during any technology transfer phase or project update meetings
                requested in advance by Keryx. PII shall inform Keryx when non-
                approvable invoices (under $5,000 items) reaches a total of
                S5,000.
<PAGE>

                                                                   [LOGO OF PII]

5. Indemnification

        5.1.    Keryx shall indemnify and hold PII and PII's affiliates and its
                and their directors, officers, employees and agents, harmless
                from and against any and all costs and expenses (including
                attorney's fees) incurred as a result of claims asserted or
                suits brought against PII and PII's affiliates, and its and
                their directors, officers, employees and agents arising out of
                (i) any negligence or willful misconduct of Keryx in performing
                the services hereunder, (ii) any misrepresentation by Keryx or
                breach by Keryx of any covenant or agreement hereunder, or (iii)
                any claim asserted by a third party that Keryx in performing the
                services hereunder has infringed or misappropriated any
                proprietary or confidential information or intellectual property
                rights of such third party arising out of materials provided by
                Keryx to PII.

        5.2.    PII shall indemnify and hold Keryx and Keryx's affiliates, and
                its and their directors, officers, employees and agents,
                harmless from and against any and all costs and expenses
                (including attorney's fees) incurred as a result of claims
                asserted or suits brought against Keryx and Keryx's affiliates,
                and its and their directors, officers, employees and agents
                arising out of (i) any negligence or willful misconduct of PII
                in performing the services hereunder, (ii) any misrepresentation
                by PII or breach by PII of any covenant or agreement hereunder,
                or (iii) any claim asserted by a third party that PII in
                performing the services hereunder has infringed or
                misappropriated any proprietary or confidential information or
                intellectual property rights of such third party.

        5.3.    In no event shall either party be liable to the other for
                consequential or indirect damages, including without limitation
                lost profits or revenues.

6. Termination

        6.1.    Keryx, but not PII, shall have the right to terminate this
                Agreement at anytime and for any reason at the sole discretion
                of Keryx.

        6.2.    Upon such termination, Keryx shall pay all costs incurred by PII
                for work performed to the date of termination, provided PII
                provides written evidence that such costs have been incurred and
                work performed.

        6.3.    Within 10 days of the termination of this Agreement, PII shall
                deliver to Keryx all data, information, reports and any and all
                related documentation which were, or required to be, developed,
                generated or derived, directly or indirectly, by PII (or by any
                subcontractor or agent of PII) for Keryx during the course of
                the project.

7. Ownership of Materials and Information

        7.1.    All data, information, reports and any and all related
                documentation, which are developed, generated or derived,
                directly or indirectly, by PII (or by any subcontractor or agent
                of PII) for Keryx during the course of the project (the "Data"),
                and all inventions,
<PAGE>

                                                                   [LOGO OF PII]

                discoveries, formulae, procedures, processes, technology and any
                other intellectual property, and any improvements thereto,
                whether patentable or not, which result or evolve directly,
                during the course of the project or as a result of the services
                performed hereunder by PII (or by any subcontractor or agent or
                PII) (the "Inventions"), shall be and remain the sole and
                exclusive property of Keryx.

        7.2.    Neither PII nor its employees or agents shall have or acquire
                any right, title or interest in such Data or Inventions, and PII
                shall promptly disclose in writing to Keryx any Inventions,
                shall assign any and all rights in any Data and Inventions to
                Keryx and shall assist Keryx in performing its rights in such
                Data and Inventions.

8. Nondisclosure

        8.1.    PII agrees that it will not use, provide to, disclose to, or
                permit any third party to use any information, data, or
                documents which were received from Keryx or which were
                specifically developed or generated by PII or any third party in
                this project for Keryx (the "Project Information").

        8.2.    PII acknowledges that the Project Information is highly
                confidential, and PII agrees to return to Keryx all such Project
                Information upon the termination of this Agreement or
                completion of this project. PII's obligations with respect to
                the Project Information shall survive this termination of this
                Agreement and the completion of this project.

9. Miscellaneous

        9.1.    Independent Contractors: PII is providing the services set forth
                in this Agreement as an independent contractor and, therefore,
                neither it, its employees, its representatives nor its agents
                shall have any authority to bind Keryx in any manner.

        9.2.    Governing Law: This Agreement and any disputes arising from it
                shall be governed by the laws of the State of New York.

        9.3.    Entire Agreement: This Agreement constitutes the entire
                agreement between the parties concerning the subject matter of
                this Agreement and supersedes any prior understanding or write
                or oral agreement. Its terms may be modified or amended only by
                a writing signed by authorized signatories of each party.
<PAGE>

                                                                   [LOGO OF PII]

AGREED AND ACCEPTED

PHARMACEUTICS INTERNATIONAL, INC.


/s/ Steve King
------------------------------
Steve King
Vice President Business Development

April 3rd 2000
------------------------------
Date

KERYX BIOPHARMACEUTICALS, INC.

/s/ Ira Weinstein
------------------------------
Authorized Agent or Representative
Title: Treasurer


March 30, 2000
------------------------------
Date

Keryx Biopharmaceuticals, Inc.

Billing Contact: Ira Weinstein
                 -------------

                 -------------

                 -------------

                 -------------
P/O Number:
                 -------------