LICENSE AGREEMENT

EXHIBIT 10.41

Portion of this exhibit marked [*] are omitted and are requested to be treated confidentially.

LICENSE AGREEMENT

THIS LICENSE AGREEMENT (the “Agreement”) is made and entered into effective this      day of October 2003 (the “Effective Date”) between aaiPharma LLC, a Delaware limited liability company having an address at 2320 Scientific Park Drive, Wilmington, NC 28405, aaiPharma Inc., a Delaware corporation having an address at 2320 Scientific Park Drive, Wilmington, NC 28405 (hereinafter referred to collectively with aaiPharma LLC as “aaiPharma”), and Salix Pharmaceuticals, Inc., a California corporation having an address at 8540 Colonnade Center Drive, Suite 501, Raleigh, NC 27615 (hereinafter referred to as “Salix”).

WITNESSETH

WHEREAS, aaiPharma has developed an azathioprine product in several strengths (the “Licensed Product,” as defined in more detail below).; and

WHEREAS, Salix seeks an exclusive license to market, promote, sell, and distribute the “Licensed Product” in the Territory, and is willing to expend its reasonable efforts and resources to do so if it can obtain a license under the terms and conditions set forth herein; and

WHEREAS, aaiPharma wishes to grant to Salix such a license, subject to the terms and conditions set forth herein.

NOW, THEREFORE, for and in consideration of the covenants, conditions, and undertakings hereinafter set forth, it is agreed by and between the parties as follows:

1. Definitions

1.1 “Competing Product” with respect to any country in the Territory shall mean a bioequivalent pharmaceutical product for human use approved by any national, federal, state or local regulatory agency, department, bureau or other government entity within the Territory, including but not limited to the United States’ Food & Drug Administration, that contains 25 mg, 75 mg, or 100 mg of azathioprine.

1.2 “GI Product” means any product indicated or developed for the treatment of gastrointestinal disease owned, developed, or licensed by aaiPharma, or any parent, subsidiary, or affiliate, other than (i) those containing omeprazole or S-omeprazole, or any derivatives thereof as an active ingredient or (ii) any 50 mg formulation of azathioprine sold by aaiPharma.

1.3 “Licensed Field” means all indications and uses for humans.

1.4 “Licensed Know-How” means (i) all know-how, trade secrets, formulations, methods of manufacture, and scientific, clinical and other data and information, whether or not patented or patentable, and any intellectual property rights, pertaining to Licensed Products for use in the Licensed Field, or pertaining to the manufacture or use of such formulations and (ii) any pharmacological, toxicological, pharmacokinetic, non-clinical data, and clinical data regarding Licensed Products available to aaiPharma and required by Salix to maintain current

1

regulatory approvals or seek and obtain regulatory approvals or intellectual property rights protection for additional indications for Licensed Products or with respect to additional jurisdictions in the Territory and which, in each case, aaiPharma has the right to disclose, license, sublicense, and/or assign, as applicable, as of the Effective Date and during the Term of this Agreement or to which aaiPharma subsequently acquires the right to disclose, license, sublicense, or assign during the Term of this Agreement in the Territory.

1.5 “Licensed Products” means any and all products for use in the Licensed Field in the Territory that incorporate 25 mg, 75 mg, or 100 mg dosage formulations of azathioprine, including but not limited to such products as are currently sold by aaiPharma for human therapeutic use. For purposes of clarification, “Licensed Products” does not include the 50 mg formulation currently sold by aaiPharma.

1.6 “Licensed Trademarks” means AZASAN and any related trade dress and domain names (including but not limited to azasan.com or azathioprine.com) used or registered for use by aaiPharma with respect to any Licensed Products or their active ingredient(s).

1.7 “Net Sales” means the total sales price invoiced to a third party by Salix or any Salix Affiliate for the Licensed Products, after deducting (a) sales taxes or other taxes separately stated on the invoice, (b) shipping charges (including but not limited to related insurance) actually paid and separately stated on the invoice, (c) actual allowances, rebates, credits and refunds for returned or defective goods, (d) chargeback payments and rebates (or the equivalent thereof) granted to managed health care organizations or to federal, state/provincial, local and other governments, including their agencies, purchasers, and/or reimbursers, or to trade customers, (e) normal and customary trade and quantity discounts, retroactive price reductions, or other allowances actually allowed or granted from the billed amount and taken, and (f) any import or export duties, tariffs, or similar charges incurred with respect to the import or export of Licensed Products into or out of a country in the Territory, provided that Net Sales shall not include amounts received from Salix Affiliates with respect to the sale or transfer of Licensed Products unless such Salix Affiliates are the end users of such Licensed Products.

1.8 “Product Approvals” means any approvals, licenses, registrations or authorizations granted by, or applications therefor made to, any national, federal, state or local regulatory agency, department, bureau or other government entity within the Territory, including but not limited to the United States’ Food & Drug Administration, necessary for the marketing, manufacture, use, storage, import, transport, or sale of Licensed Products in a regulatory jurisdiction in the Territory, including but not limited to those listed on Appendix A , attached hereto and incorporated herein by reference, and all correspondence, filings, and documents related thereto.

1.9 “Affiliate” means any firm, person or company which controls, is controlled by or is under common control with a party to this Agreement; as used in this definition, “control” means the possession, directly or indirectly, of the power to direct or cause the direction of the management and policies of such firm, person or company, whether through the ownership of voting securities, by contract or otherwise.

2

1.10 “Supply Agreement” means the separate Supply Agreement, dated as of the Effective Date, between Salix and aaiPharma under which aaiPharma shall supply, and Salix shall purchase, all of Salix’s and the Salix Affiliates’ needs for Licensed Product.

1.11 “Territory” means Canada, Mexico, and the United States of America and its territories and possessions, including the Commonwealth of Puerto Rico.

2. Effectiveness; Grant of License; Term; Options .

2.1 Effectiveness . This Agreement shall only be effective upon the execution of the Supply Agreement and Quality & Compliance Agreement by each party hereto.

2.2 Exclusive License . Upon execution of this License Agreement, Salix shall pay aaiPharma [ * ] United States Dollars ($ [ * ] ). Upon receipt thereof, aaiPharma grants to Salix an exclusive royalty -bearing license to make and have made (solely (i) as permitted by the terms of Sections 3.1 and 3.10 of the Supply Agreement or (ii) upon expiration or termination of the Supply Agreement), use, offer for sale, market, promote, sell, import and export (solely among jurisdictions within the Territory), and distribute, and, for purposes of clarification but not limitation, enter into agreements with third parties, including Salix Affiliates, to co-promote and distribute within the Territory, the Licensed Products in the Territory under the Licensed Trademarks, or any other trademarks owned or licensed by Salix or its Affiliates, for all uses in the Licensed Field upon the terms and conditions set forth in this Agreement (the “Distribution and Trademark License”). In addition to the Distribution and Trademark License, aaiPharma grants Salix the right to use the marketing or advertising materials provided hereunder to market, offer for sale, sell, promote and distribute the Licensed Products in the Territory. Except with respect to existing inventories of Licensed Products no longer in aaiPharma’s reasonable control as of the Effective Date, aaiPharma shall no longer sell any Licensed Products. This Distribution and Trademark License is not intended to expand aaiPharma’s manufacturing and supply obligations, which are fully described in the Supply Agreement.

2.3 License Term . This agreement is effective as of the Effective Date and shall continue in perpetuity, unless otherwise terminated pursuant to Sections 2.4(b)(2), 10, or 11 below (the “Term”).

2.4 Assignment Option .

(a) Grant of Assignment Option . If, at any time during the Term but after the date [ * ] months following the Effective Date, (i) aaiPharma terminates its obligation to supply Licensed Products to Salix pursuant to the Supply Agreement, (ii) aaiPharma otherwise ceases, absent proper notice, to supply Licensed Products to Salix pursuant to the Supply Agreement, or (iii) either Salix or aaiPharma, respectively, sells, transfers, or otherwise disposes of all or substantially all of its assets to, or merges or consolidates into, in a single transaction or series of related transactions, an entity that is not controlled, directly or indirectly,

3

by the stockholders of Salix or aaiPharma, respectively, immediately prior thereto (a “Salix Acquisition” and “aaiPharma Acquisition,” respectively), Salix has the option to cause aaiPharma to assign to Salix all of aaiPharma’s right, title, and interest to (i) Licensed-Know How, (ii) Licensed Products, (iii) Licensed Trademarks, (iv) Product Approvals, and (v) any intellectual property rights (including but not limited to patent rights), licenses, or other agreements or rights held by aaiPharma and necessary for the manufacture, supply, and sale of Licensed Products in the Territory, free and clear of any liens, claims, or encumbrances (the “Assignment Option”). The parties acknowledge and agree that the Assignment Option shall not include the assignment of any aaiPharma rights, title or interest outside the Territory.

(b) Exercise of Assignment Option

(1) aaiPharma shall (i) provide written notice to Salix regarding the cessation of its supply obligations to Salix pursuant to the Supply Agreement and (ii) provide written notice to Salix as soon as reasonably possible, but not later than [ * ] days, in advance of any aaiPharma Acquisition (collectively, “aaiPharma Notice”). Salix shall provide written to aaiPharma as soon as reasonably possible, but no later than [ * ] days, in advance of any Salix Acquisition (“Salix Notice”). The Assignment Option may be exercised by Salix by written notice to aaiPharma and payment of the Option Fee pursuant to Section 3.2 at any time within one (1) year following (i) its receipt of the aaiPharma Notice, (ii) aaiPharma’s failure, absent proper notice, to supply Licensed Products to Salix pursuant to the Supply Agreement, or (iii) its sending the Salix Notice. aaiPharma agrees to reasonably cooperate with Salix in its evaluation of the Assignment Option and respond to any questions Salix reasonably may have regarding such evaluation, including but not limited to details concerning the aaiPharma Acquisition as it relates to the Licensed Products, Licensed Trademarks, and any intellectual property rights (including but not limited to patent rights), licenses, or other agreements or rights necessary for the use, manufacture, supply, and sale of Licensed Products in the Territory.

(2) In the event that Salix exercises its Assignment Option, (i) aaiPharma shall immediately assign all of aaiPharma’s right, title, and interest to the (i) Licensed Know-How, (ii) Licensed Products, (iii) Licensed Trademarks, (iv) Product Approvals, and (v) any intellectual property rights (including but not limited to patent rights), licenses, or other agreements or rights held by aaiPharma and necessary for the use, manufacture, supply, and sale of Licensed Products in the Territory to Salix and provide Salix with copies of all books, records, and correspondence in its possession regarding the foregoing and (ii) this Agreement shall immediately terminate, subject to the further provisions of Section 12.3. Upon such exercise, aaiPharma and Salix shall negotiate in good faith a definitive asset purchase agreement providing for the assignment and transfer of such intellectual property and other materials, which agreement shall include representations and warranties and other terms and provisions customary in similar agreements.

4

2.5 Right of First Discussion - GI Products .

(a) Grant of Right . aaiPharma grants to Salix the, first option to discuss (i) an exclusive license to any GI Product, with exclusive rights of sublicense, and (ii) an exclusive license to any Licensed Products for jurisdictions outside the Territory, with exclusive rights of sublicense, as described below (the “GI Product Option”). aaiPharma shall notify Salix in writing of the availability of any such GI Product, including reasonably sufficient detail, as determined in aaiPharma’s sole reasonable discretion, to enable Salix to evaluate its interest in licensing such GI Product, and Salix shall have a period of [ * ] days from the receipt of such disclosure (the “Evaluation Period”) within which to exercise such option in writing with respect to such GI Product.

(b) Exercise of Right . If Salix exercises its option with respect to a particular GI Product, the parties shall have an additional [ * ] day period following Salix’s exercise of its GI Product Option within which to negotiate in good faith during the Evaluation Period the terms of the license (the “Negotiation Period”). If Salix declines its option or fails to exercise its option with respect to such GI Product within the Evaluation Period, or the parties are unable to reach material agreement on the terms of a license agreement during the Negotiation Period with respect to such GI Product, aaiPharma shall be free to license its rights in such GI Product to any third party.

(c) 50 mg Formulation .

(1) aaiPharma grants to Salix the exclusive, first option to acquire an exclusive license, with exclusive rights of sublicense, to any 50 mg formulation of azathioprine (“50 mg Product”) if aaiPharma seeks to license such product to a third party, as described below (the “50 mg Option”). aaiPharma shall notify Salix in writing of the availability of any 50 mg Product, including reasonably sufficient detail, as determined in aaiPharma’s sole discretion, to enable Salix to evaluate its interest in licensing such 50 mg Product, and Salix shall have a period of [ * ] days from the receipt of such disclosure (the “50 mg Evaluation Period”) within which to exercise such option in writing with respect to such 50 mg Product. aaiPharma shall not offer, discuss, negotiate, or enter into a commercial license with any third party with respect to any 50 mg Product without first complying with the terms of the option described in this Section 2.5(c). The 50 mg Option shall be exercisable during the term of this Agreement and, if Salix exercises its Assignment Option pursuant to Section 2.4(b) above and is assigned the rights, titles, and interests to be assigned upon such exercise, for a period of [ * ] years following such assignment.

(2) If Salix exercises its option with respect to a 50 mg Product, the parties shall have an additional [ * ] day period following Salix’s exercise of its 50 mg Option within which to negotiate in good faith the terms of the license (the “50 mg Negotiation Period”), which terms shall be commercially reasonable and fairly reflect the relative contributions of both parties. If Salix declines its option or fails to exercise its option with

5

respect to such 50 mg Product within the 50 mg Evaluation Period, or the parties are unable to reach material agreement on the terms of a license agreement during the 50 mg Negotiation Period with respect to such 50 mg Product, aaiPharma shall be free to license its rights in such 50 mg Product to any third party.

3. Royalties and Option Fee

3.1 Royalties . Beginning on the first commercial sale of the Licensed Product in the Territory by Salix or a Salix Affiliate, Salix will pay earned royalties on all Net Sales of Licensed Product(s) purchased during the Term by Salix or Salix Affiliates pursuant to subsections (a) and (b) below.

(a) Prior to the marketing or sale of a Competing Product in the Territory during the Term of the Agreement, the royalty rate payable by Salix shall be [ * ] percent ( [ * ] %) of Net Sales.

(b) Following the marketing or sale of a Competing Product in the Territory during the Term of the Agreement, the royalty rate payable by Salix for sales within the country in which such Competing Product is sold shall be [ * ] percent ( [ * ] %) of Net Sales in the relevant country and shall remain at [ * ] percent ( [ * ] %) of Net Sales in all other countries within the Territory in which no Competing Product is sold.

3.2 Option Fee . Upon exercise of the Assignment Option pursuant to Section 2.5, Salix shall pay aaiPharma an amount equal to the difference between (i) [ * ] times total Net Sales for the [ * ] month period (represented by the last [ * ] quarterly reports provided by Salix pursuant to Section 3.3) prior to the month in which Salix provides written notice of its exercise of the Assignment Option and (ii) [ * ] Dollars ($ [ * ] ), provided that, in any event, the amount payable hereunder shall not exceed [ * ] Dollars ($ [ * ] ). The amount denoted above shall be the total consideration paid to aaiPharma by Salix in connection with the exercise of such Assignment Option and for the assignments and transfers associated therewith; Salix shall not be required to pay any additional amounts of any kind in connection with its exercise of the Assignment Option, the assignment and transfer of all rights, materials, and assets to be acquired upon such exercise, or the undertaking of any related activities by aaiPharma as necessary to effect the exercise of the Assignment Option and all such assignments and transfers.

3.3 Reporting . Salix shall make quarterly written reports to aaiPharma, within thirty (30) days after the first day in each January, April, July, and October during the Term, stating the number, description, and aggregate Net Sales of Licensed Products sold or transferred during the preceding three calendar months and calculating the royalty payable as provided in Section 3.1. Until Salix or a Salix Affiliate has achieved the first commercial sale of a Licensed Product, a report shall be submitted by Salix at the end of each January and July after the Effective Date of

6

this Agreement describing Salix’s marketing efforts made towards such first commercial sale in the Territory for all Licensed Products.

3.4 Payment . Concurrently with the delivery of the reports under Section 3.3, Salix shall pay to aaiPharma royalties on the Net Sales of the Licensed Products included therein or due for that period, in U.S. dollars at the royalty rates specified in Section 3.1, with the rate of exchange for any Net Sales of Licensed Product denominated in a currency other than U.S. dollars being the exchange rate which is the arithmetic mean of the opening telegraphic transfer selling and buying rate published by the American edition of the Wall Street Journal. U.S.-dollar equivalence shall be calculated on a quarterly basis, using the average of the exchange rate on the first and last business day of the quarter during the Term of this Agreement for each of the currencies in which Net Sales of Licensed Product(s) were made during the quarter. All payments due to aaiPharma under this Agreement shall be made in full without deduction for taxes, assessments or other charges of any kind or description; provided that Salix may only deduct any existing or future withholding taxes for taxes based on aaiPharma’s income which Salix is required to pay or withhold in the Territory on behalf of aaiPharma from any payment and royalty due hereunder as long as Salix provides aaiPharma with such documents as may reasonably be necessary to enable or assist aaiPharma to claim any available exemption therefrom.

3.5 Records; Audits . Salix shall keep, and shall ensure that the Salix Affiliates keep, complete, true and accurate books of account and records showing Net Sales and the derivation of all amounts payable to aaiPharma in connection with this Agreement. Such books of record shall be preserved for a period not less than two (2) years after their creation. Salix agrees to make these books of record available for audit by a nationally-recognized, independent accounting firm designated by aaiPharma, upon reasonable prior written notice and during normal business hours, but no more than once every twelve (12) months, for purposes of confirming proper payment of royalties under this Agreement. The records shall be treated as confidential, except as may be required in connection with the royalty obligations of this Agreement or aaiPharma’s royalty obligations to its licensors (if any). Such audits shall be at the expense of aaiPharma, unless an underpayment in excess of [ * ] percent ( [ * ] %) is discovered in the course of any such audit, whereupon all reasonable, documented costs relating thereto shall be paid by Salix. Salix will promptly pay to aaiPharma the full amount of any underpayment determined by an audit under this section as well as any audit costs due pursuant to the immediately preceding sentence; aaiPharma will promptly pay to Salix the full amount of any overpayment determined by an audit under this section.

4. Adverse Event Reporting; Product Approvals .

4.1 Upon execution of this Agreement and from time to time, as reasonably requested by Salix, aaiPharma shall, provide Salix with (i) copies of Product Approvals and (ii) Licensed Know-How, including the availability of data and results obtained from non-clinical and clinical

7

studies of the Licensed Products performed by aaiPharma, its consultants, contractors, agents, or other representatives. Upon the reasonable request of Salix, aaiPharma shall provide Salix with copies of such data and results that aaiPharma is legally entitled to disclose. Additionally, aaiPharma shall assist Salix in any reasonable manner with respect to Product Approvals (including but not limited to those that Salix may pursue with respect to additional indications or jurisdictions), as shall be reasonably requested by Salix as necessary to enable Salix to manufacture, sell, use, offer for sale, distribute, and market Licensed Products to the extent permitted by this Agreement, including but not limited to the assignment of any Product Approvals and provision and/or obtaining of appropriate correspondence, clearance or transfer letters, or any other form of authorization, license, permit, or the like from regulatory authorities with respect to Product Approvals, provided that Salix shall keep aaiPharma fully informed of such efforts and shall provide aaiPharma with copies of such correspondence. [ * ]

4.2. Salix shall have the right, so long as such actions are not inconsistent with the terms of this Agreement and the Supply Agreement, to make amendments to the Product Approvals, make additional applications thereunder, conduct such studies, or undertake any and all such actions as are necessary in order to maintain and apply for any marketing or product approvals, licenses, registrations or authorizations in the Territory with respect to Licensed Products, including but not limited to any such approvals with respect to (i) additional indications for Licensed Products or (ii) additional jurisdictions in the Territory, provided that Salix shall keep aaiPharma fully informed of such efforts, and shall provide aaiPharma with copies of such correspondence.

4.3 Each party shall report to the other in writing the occurrence or reporting of any adverse event occurring with respect to a Licensed Product to the other party immediately following a party’s receiving notice or otherwise becoming aware thereof for so long as aaiPharma owns any right, title, and interest to any product approvals, licenses, registrations or authorizations regarding Licensed Products. The recorded owner of the Product Approval in the relevant portion of the Territory shall be responsible for reporting to the appropriate regulatory authorities all adverse events related to the use of Licensed Products.

5. Generic Relabeling; Marketing Materials; Existing Agreements .

5.1 Upon execution of this Agreement, aaiPharma shall, [ * ] .

5.2 Upon execution of this Agreement, aaiPharma shall cease to use the Licensed Trademarks, and trade dress associated therewith. Notwithstanding the foregoing, aaiPharma shall not be required to remove or relabel any 50 mg azathioprine product that has already been sent to a third party for distribution as of the Effective Date.

5.3 aaiPharma agrees to supply Salix with marketing and advertising materials, including but not limited to sales training materials, non-confidential customer information,

8

promotional and marketing books and records, pamphlets, and other promotional items, in its possession pertaining to the Licensed Products, and to destroy any marketing and advertising materials in its possession that use or incorporate the Licensed Trademarks for products other than Licensed Products.

5.4 aaiPharma shall, in addition to, and without limitation of, any legal or equitable remedies available to Salix as a result of any breach by aaiPharma of this Agreement, be fully responsible and liable for any and all returns, rebates, chargebacks, discounts, other claims made by any third party, or any other financial liability or other liability of any kind related to Licensed Products manufactured and distributed by aaiPharma. Similarly, Salix shall, in addition to, and without limitation of, any legal or equitable remedies available to aaiPharma as a result of any breach by Salix of this Agreement, be fully responsible and liable for any and all returns, rebates, chargebacks, discounts, other claims made by any third party, or any other financial liability or other liability of any kind related to Licensed Products distributed by Salix, excluding only any liability (i) arising as a result of breach of this Agreement by aaiPharma or the negligence or willful misconduct of aaiPharma or (ii) otherwise indemnified by aaiPharma under this Agreement or the Supply Agreement.

5.5 As requested by Salix, aaiPharma shall use commercially reasonable efforts to (i) promptly assign, terminate, or remove the Licensed Products from, any existing agreements between aaiPharma and third parties that relate to the sale, marketing, o