<PAGE>
                                                                    EXHIBIT 10.1

[Certain information has been omitted from this document pursuant to a request
for confidential treatment submitted to the Securities and Exchange Commission
and the omitted information has been separately submitted to the Securities and
Exchange Commission.]


                   FIRST AMENDMENT TO INTERIM SUPPLY AGREEMENT

This FIRST AMENDMENT TO INTERIM SUPPLY AGREEMENT (the "Amendment") is made this
22nd day of July 2003, by and between ASTRAZENECA LP, a Delaware limited
partnership ("Manufacturer"), and AAIPHARMA LLC, (f/k/a NeoSan Pharmaceuticals
Inc.), a Delaware limited liability company ("Company") and wholly-owned
subsidiary of aaiPharma Inc.

WHEREAS, Manufacturer and Company are parties to that certain Interim Supply
Agreement, dated as of August 17, 2001, (the "Supply Agreement") relating to the
Manufacture of Products by Manufacturer for Company; and

WHEREAS, the parties now wish to amend certain terms and conditions of the
Supply Agreement as set forth herein.

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants
and agreements contained herein, the receipt and sufficiency of which are hereby
acknowledged by the parties hereto, the parties, intending to be legally bound,
hereby agree as follows:

         1.       DEFINITIONS. All capitalized terms used and not defined herein
shall have the meanings ascribed thereto in the Supply Agreement.

         2.       AMENDMENT OF SECTION 1.1.

         The following definitions in Section 1.1 of the Supply Agreement are
hereby amended or added as follows:

                  2.1      Section 1.1(a) ("Active Pharmaceutical Ingredient")
         is amended by adding the following sentence at the end of this
         subsection:

                           "Upon the approval of each Reformulation NDA, Exhibit
                           B shall be amended to include the active
                           pharmaceutical ingredients as specified in the
                           applicable Reformulation NDA."

                  2.2      Section 1.1(d) ("Approved Reformulation") shall be
         recaptioned in the plural, i.e., as "Approved Reformulations".

                  2.3      Section 1.1(bb) ("Manufacturing Fee") is amended by
         replacing the words "Section 5.1" with the words "Section 6.1".

                  2.4      Section 1.1(kk) ("Registrations") is amended by
         adding the following phrase immediately prior to the period:

                           "and, once approved by the FDA, each of the
                           Reformulation NDAs and the SNDA to NDA 8-809."

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                  2.5      Section 1.1(mm) ("Specifications") is amended by
         adding the following phrase immediately prior to the period:

                           "and, as appropriate, in accordance with the
                           reformulation approved under each of the
                           Reformulation NDAs and the SNDA to NDA 8-809, once
                           approved by the FDA. Additional Specifications will
                           be provided by Company and incorporated into the
                           Agreement upon approval of the applicable NDA and
                           SNDA."

                  2.6      A new subsection (tt) is added and reads as follows:

                           "New Drug Application" means a New Drug Application
                           submitted in accordance with the federal Food, Drug
                           and Cosmetic Act, as amended.

                  2.7      A new subsection (uu) is added and reads as follows:

                           "MVI-Adult (bulk)" means MVI-Adult bulk solution that
                           is comprised of a three-vitamin component and a
                           ten-vitamin component (which contains vitamin K).

                  2.8      A new subsection (vv) is added and reads as follows:

         [Certain information has been omitted from this document pursuant to a
         request for confidential treatment submitted to the Securities and
         Exchange Commission and the omitted information has been separately
         submitted to the Securities and Exchange Commission.]

                  2.9      A new subsection (ww) is added and reads as follows:

                           "MVI-Adult" means the MVI-12 Product that has been
                           reformulated in accordance with the Federal Register
                           Notice published by the FDA on April 20, 2000 [Docket
                           No. 79N-0113] and is the subject of NDA 21-625.

                  2.10     A new subsection (xx) is added and reads as follows:

         [Certain information has been omitted from this document pursuant to a
         request for confidential treatment submitted to the Securities and
         Exchange Commission and the omitted information has been separately
         submitted to the Securities and Exchange Commission.]

                  2.11     A new subsection (yy) is added and reads as follows:

                           "Reformulation NDA" means each of (i) New Drug
                           Application 21-643 filed by Manufacturer on behalf of
                           Company with FDA (relating to MVI-Adult (pharmacy
                           bulk package)), as the same may be amended or
                           supplemented,


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<PAGE>

                           and (ii) New Drug Application 21-625 filed by
                           Manufacturer on behalf of Company with FDA (relating
                           to other packaging configurations of MVI-Adult), as
                           the same may be amended or supplemented.

                  2.12     A new subsection (zz) is added and reads as follows:

                           "MVI-Adult Products" means MVI-Adult (bulk),
                           MVI-Adult, and MVI-Adult (pharmacy bulk package)."

                  2.13     A new subsection (aaa) is added and reads as follows:

         [Certain information has been omitted from this document pursuant to a
         request for confidential treatment submitted to the Securities and
         Exchange Commission and the omitted information has been separately
         submitted to the Securities and Exchange Commission.]

                  2.14     A new subsection (bbb) is added and reads as follows:

                           "MVI-Adult (pharmacy bulk package)" means the MVI-12
                           Product that has been reformulated in accordance with
                           the Federal Register Notice published by the FDA on
                           April 20, 2000 [Docket No. 79N-0113] and is the
                           subject of NDA 21-643.

         3. AMENDMENT OF SECTION 3.6

                  Section 3.6 of the Supply Agreement is hereby deleted in its
         entirety and replaced by the following:

"Company acknowledges that Manufacturer is attempting to reformulate, on behalf
of Company, the Product currently marketed and sold as "MVI-12" (the "MVI-12
Product") in accordance with the Federal Register Notice published by the FDA on
April 20, 2000 [Docket No. 79N-0113]. In addition, Manufacturer, on behalf of
the Company, has submitted the Reformulation NDAs to the FDA. Company is
responsible for [Certain information has been omitted from this document
pursuant to a request for confidential treatment submitted to the Securities and
Exchange Commission and the omitted information has been separately submitted to
the Securities and Exchange Commission.] Manufacturer and Company agree that
without further action or deed (a) if and when New Drug Application 21-625 is
approved by the FDA, all references to Product in the Supply Agreement will
thereafter also include MVI-Adult in the single-dose packaging configurations
specified in such New Drug Application, and MVI-Adult (bulk); (b) if and when
New Drug Application 21-643 is approved by the FDA, all references to Product in
the Supply Agreement will thereafter also include MVI-Adult (pharmacy bulk
package) in the packaging configurations specified in such New Drug Application;
and (c) if and when the SNDA is approved by FDA, this Supply Agreement will be
amended so that all references to Product will thereafter also include [Certain
information has been omitted from this document pursuant to a request for
confidential treatment submitted to the Securities and Exchange Commission and
the omitted information has been separately submitted to the Securities and
Exchange Commission.]


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<PAGE>

At such time as each Reformulation NDA and the SNDA is approved, the parties
shall discuss and use good faith efforts to mutually agree upon a transition
plan for the Manufacture hereunder of the applicable MVI-Adult Product and
Reformulated MVI-12 Product and the discontinuation of the corresponding MVI-12
Product such that each transition will be completed within six (6) months of the
applicable approval; provided that Manufacture of the MVI-Adult Products and
Reformulated MVI-12 Products shall be implemented in accordance with Sections
3.1 and 3.2. All changes to the Specifications and the Manufacturing processes
for the Products (including, without limitation, changes to or additions of
Active Pharmaceutical Ingredients and Raw Materials) that are caused by or
result from the Manufacture hereunder of MVI-Adult Products and Reformulated
MVI-12 Products shall be deemed changes requested by the Company pursuant to
Section 2.4.

         4. AMENDMENT OF SECTION 6.1

                  Effective as of August 18, 2003, Section 6.1 is deleted in its
entirety and replaced by the following:

"The price for the supply of each Product (the "Manufacturing Fee") is listed on
Schedule 6.1 "Manufacturing Fees" [Certain information has been omitted from
this document pursuant to a request for confidential treatment submitted to the
Securities and Exchange Commission and the omitted information has been
separately submitted to the Securities and Exchange Commission.] Effective as of
August 18, 2005 and on each anniversary of the Effective Date thereafter, the
Manufacturing Fees will be increased by [Certain information has been omitted
from this document pursuant to a request for confidential treatment submitted to
the Securities and Exchange Commission and the omitted information has been
separately submitted to the Securities and Exchange Commission.] Notwithstanding
the foregoing, if any MVI-Adult Products and Reformulated MVI-12 Products are
Manufactured prior to August 18, 2003, the Manufacturing Fee for such Products
shall be in accordance with the Manufacturing Fees contained in Exhibit 6.1
hereto, as amended.

         5. AMENDMENT OF SECTION 8.1

                  Section 8.1 is amended by replacing the words "the second
anniversary thereof" with the date "August 17, 2008" and by replacing the
proviso therein in its entirety with the following:

                  "provided, however, (a) Company may from time to time, by
                  giving six months prior written notice, terminate this Supply
                  Agreement with respect to any or all of the Products, and (b)
                  Manufacturer may terminate this Supply Agreement with respect
                  to any or all of the Products on twenty-four (24) months'
                  prior written notice given at any time commencing on or after
                  August 17, 2004."

         6. AMENDMENT OF SECTION 9.1


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<PAGE>

                  Section 9.1 is amended by adding the phrase "the inability to
obtain Active Pharmaceutical Ingredients and/or Raw Materials," after the word
"limitation" in the sixth line of the first sentence.

         7. AMENDMENT OF SCHEDULE 1.1

                  Schedule 1.1 of the Supply Agreement is deleted and shall be
replaced in its entirety by the new Schedule 1.1 attached hereto.

         8. AMENDMENT OF SCHEDULE 3.2

                  Schedule 3.2 of the Supply Agreement is deleted and shall be
replaced in its entirety by the new Schedule 3.2 attached hereto. In the event
that Company elects to purchase the requisite additional filling and support
equipment for installation in Manufacturer's facility in 2005 or thereafter, the
maximum annual quantities set forth in such Schedule 3.2 for the MVI-Adult
Products and Reformulated MVI-12 Products shall return to the levels set forth
in such Schedule 3.2 for 2003.

         9. AMENDMENT OF SCHEDULE 5.1

                  Effective August 18, 2003, Schedule 5.1 of the Supply
Agreement is deleted and shall be replaced in its entirety by the new Schedule
6.1 attached hereto.

         10. ASSIGNMENT

                  Section 13.2 is hereby deleted in its entirety and replaced by
the following:

                  "This Agreement may not be assigned by either party, in whole
                  or in part, without the prior written consent of the other
                  party, which consent shall not be unreasonably withheld.
                  Notwithstanding the foregoing, either party may assign this
                  entire Agreement and its rights and obligations hereunder to
                  (i) any of its Affiliates with a guarantee of performance by
                  the assigning party, or (ii) an assignee with net worth at
                  least equal to assignor's net worth and which agrees to assume
                  all of assignor's relevant obligations thereunder. Any
                  assignment in violation of this Section shall be void. All
                  validly assigned rights and obligations of the parties shall
                  be binding upon and inure to the benefit of and be enforceable
                  against the permitted assigns of such party. If either party
                  seeks and obtains the other party's consent to assign its
                  rights or obligations to a third party, the assignee shall
                  assume all rights and obligations of its assignor under this
                  Agreement."

         11. NO OTHER AMENDMENTS. Except as expressly amended hereby, all other
terms and conditions of the Supply Agreement shall remain in full force and
effect.

         12. HEADINGS. The headings used in this Amendment have been inserted
for convenience of reference only and do not define or limit the provisions
hereof.


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<PAGE>

         13. GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF DELAWARE APPLICABLE TO CONTRACTS
EXECUTED AND PERFORMED IN SUCH STATE, WITHOUT GIVING EFFECT TO CONFLICTS OF LAWS
PRINCIPLES.

         14. COUNTERPARTS. This Amendment may be executed in any number of
counterparts and by facsimile, each of which will be deemed an original, but all
of which together will constitute one and the same instrument.

IN WITNESS WHEREOF, the parties have caused their respective duly authorized
officers to execute this Amendment which shall be effective as of the day and
year first above written.



AAIPHARMA LLC



By: /S/ DAVID M. HURLEY
Name: David M. Hurley
Title:  President
Date: July 22, 2003



ASTRAZENECA LP



By: /S/ GLENN M. ENGELMANN
Name: Glenn M. Engelmann
Title: Attorney in Fact
Date: July 25, 2003


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<PAGE>

                      AMENDMENT TO AAIPHARMA INC. GUARANTY

         WHEREAS, pursuant to a Guaranty attached to the Interim Supply
Agreement (the "Agreement"), dated as of August 17, 2001, by and between
AstraZeneca LP ("Manufacturer"), and aaiPharma LLC, f/k/a NeoSan Pharmaceuticals
Inc. ("Company"), a wholly-owned subsidiary of aaiPharma Inc., aaiPharma Inc.
has guaranteed the performance by Company of its obligations under the
Agreement; and

         WHEREAS, Manufacturer and Company have amended the Agreement on the
foregoing terms and conditions.

         NOW, THEREFORE, in consideration of Manufacturer's entering into, and
continued performance under, the Agreement, the Guaranty is hereby amended to
add the phrase, "as amended from time to time," immediately after the word
"Agreement" in the fourth line thereof.

         IN WITNESS WHEREOF, aaiPharma Inc. has caused its duly authorized
officer to execute this amendment which shall be effective as of July 22, 2003.



                                       aaiPHARMA Inc.



                                       By: /S/ PHILIP S. TABBINER
                                          --------------------------------------
                                          Name: Philip S. Tabbiner


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