CHANGE OF CONTROL AGREEMENT

Exhibit 10.12

CHANGE OF CONTROL AGREEMENT

THIS CHANGE OF CONTROL AGREEMENT (“Agreement”) dated as of March 19, 2002 is entered by and between Stefan Aigner (“Executive”) and Reliant Pharmaceuticals, LLC, a Delaware limited liability company (the “Company”).

WITNESSETH:

WHEREAS, Executive is an employee of the Company and has made and is expected to continue to make major contributions to the short and long term profitability, growth and financial strength of the Company;

WHEREAS, the Company recognizes that the possibility of a Change of Control (as defined below) exists; and

WHEREAS, the Company believes it is in the best interests of the Company and its Members to provide an incentive for Executive’s continued employment and assistance in consummating any such Change of Control.

NOW THEREFORE, in exchange for the good and valuable consideration set forth herein, the adequacy of which is specifically acknowledged, the Company and Executive hereby agree as follows:

1. Certain Defined Terms. Capitalized terms used but not otherwise defined in this Agreement have the meanings ascribed to them in the LLC Agreement. In addition to terms defined elsewhere in this Agreement, the following capitalized terms shall have the meanings ascribed below when used in this Agreement:

(a) “Benefits” shall mean medical, dental, and group term life plans as are established by the Company and as in effect from time to time applicable to executives of the Company or any Successor.

(b) “Cause” shall mean termination by the Company of the Executive’s relationship with the Company due to (i) the commission by the Executive of an act of fraud or embezzlement against the Company or any affiliate thereof, (ii) a breach by the Executive of one or more of the following duties to the Company: (A) the duty of loyalty, (B) the duty not to engage in self-dealing with respect to the Company’s assets, properties or business opportunities, except as approved in writing by the Board, (C) the duty of honesty or (D) any other fiduciary duty which the Executive owes to the Company, (iii) a conviction of the Executive (or a plea of nolo contendere in lieu thereof) for (A) a felony or (B) a crime involving fraud, dishonesty or moral turpitude, (iv) intentional misconduct with respect to his duties to the Company, including, but not limited to, knowing and intentional violation by the Executive of written policies of the Company, including policies regarding confidential information and non-competition, or specific directions of the Board or superior officers of the Company, which policies or directives are neither illegal (or do not involve illegal conduct) nor do they require the Executive to violate reasonable business ethical standards, or (v) the failure of the Executive, after written notice from the Company, to render services to the Company in accordance with his employment or other relationship with the Company, which failure is not cured within 10 days of receipt of such notice.

(c) “Change of Control” shall mean (i) the sale, lease, exchange, license or other disposition of all or substantially all of Company’s assets in one transaction or series of related transactions (an “Asset Sale”); (ii) a merger or consolidation as a result of which the holders of Company’s issued and outstanding voting securities immediately before such transaction own or control less than a majority of the voting securities of the continuing or surviving entity immediately after such transaction and/or (iii) the acquisition (in one or more transactions) by any Person or Persons acting together or constituting a “group” under Section 13(d) of the Exchange Act together with any affiliates thereof (other than Members of the Company as of the date hereof and their respective affiliates) of beneficial ownership (as defined in Rule 13d-3 under such Exchange Act) or control, directly or indirectly, of at least eighty percent (80%) of the total voting power of all classes of securities entitled to vote generally in the election of the Company’s board of managers or similar governing body; provided that for the purposes of the immediately preceding clause (iii) neither a public offering of Company’s securities nor any financing transaction or series of financing transactions shall constitute a Change of Control.

(d) “Closing Date” shall mean the effective date of a Change of Control.

(e) “Common Units” shall mean the Class A common units of the Company.

(f) “Consideration” shall mean the consideration (whether cash, stock or other property) actually received by (i) the Members of the Company in a Change of Control for or on account of their Units and (ii) employees or former employees of the Company on account of their Options.

(g) “Employment Agreement” shall mean the Amended and Restated Employment and Non-Competition Agreement dated as of July 6, 2000 by and between the Company and Executive.

(h) “Good Reason” shall mean (i) Good Reason within the meaning of the Employment Agreement, (ii) Executive is not offered continued employment with the successor entity in the Change of Control that is comparable in compensation and generally comparable in position and duties (taking into consideration the Change of Control) to Executive’s compensation, position and duties in effect immediately prior to the Closing Date, (iii) following the Closing Date and without Executive’s consent, Executive is relocated for at least six (6) months by the Company (or its successor in the Change of Control) to a location more than seventy-five (75) miles from Executive’s current principal place of employment or (iv) in connection with an Asset Sale, failure by the Successor to assume the Employment Agreement.

(i) “Liquidation Preference” shall mean the sum of (a) the Series A Liquidation Preference and (b) the Series B Liquidation Preference.

(j) “LLC Agreement” shall mean the Second Amended and Restated Limited Liability Company Operating Agreement of Reliant Pharmaceuticals, LLC, dated as of February 21, 2002, among the Members named therein, as amended from time to time.

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(k) “Option” shall mean outstanding options to purchase Common Units granted pursuant to the Plan.

(l) “Plan” shall mean the Reliant Pharmaceuticals LLC Equity Incentive Plan dated as of July 6, 2001, as amended.

(m) “Restricted Units” shall mean Common Units acquired upon exercise of any unvested Option or otherwise granted to the Executive under the terms of or subject to the Plan.

(n) “Successor” means a successor in interest to the Company or the Company’s assets in a Change of Control.

(o) “Value” means the total value of Consideration actually received by the Series A Holders and Series B Holders, as the case may be, in a Change of Control that would be applied in satisfaction of such holders’ Liquidation Preference.

2. Term of Agreement. This Agreement shall be effective on the Closing Date for a period of nine (9) consecutive months immediately following the Closing Date; provided, that any rights of Executive and/or the Company which are triggered and accrue hereunder during the term of this Agreement shall survive the termination of this Agreement to the extent so accrued.

3. Amendment of Employment Agreement. During the term of this Agreement, any provisions of the Employment Agreement that are inconsistent with the terms of this Agreement shall be amended to conform to the terms of this Agreement. Without limiting the foregoing, it is specifically understood and agreed that (a) during the term of this Agreement the definitions of Cause and Good Reason contained herein shall supercede and replace those contained in the Employment Agreement and (b) subject to the terms hereof, the Employment Agreement will remain in full force and effect in accordance with its terms.

4. Severance. If during the term of this Agreement, Executive’s employment is terminated without Cause or for Good Reason, then such termination shall be treated as a termination without Cause or for Good Reason pursuant to the terms of the Employment Agreement and the Executive shall be entitled to rights provided thereunder in respect of such termination. In the event of an Asset Sale, the Company’s obligations under the Employment Agreement to continue providing the Benefits following a termination without Cause or for Good Reason shall cease, unless otherwise required by law, and/or any Successor agrees to continue providing such Benefits. In addition, if Executive becomes entitled to receive Benefits under any subsequent employer’s benefit and/or welfare plans, the Company’s obligations to continue the Benefits as a result of termination without Cause or for Good Reason under the Employment Agreement shall cease.

5. Bonus.

(a) Subject to Section 5(c) below, in the event that (i) a Change of Control occurs prior to (A) the date the Company first offers its equity securities to the public pursuant to an effective registration statement under the Securities Act of 1933, as amended, or (B) the date on which the Series A Holders and Series B Holders convert 50% or more of their Series A

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Preferred Units and Series B Preferred Units, respectively, to Common Units in accordance with Section 6.2 of the LLC Agreement, (ii) the Executive is terminated without Cause or terminates his employment under the circumstances described in clauses (ii) or (iii) of the definition of Good Reason, and (iii) upon the Change of Control the Series A Holders and Series B Holders receive aggregate Value equal to at least the Liquidation Preference, but not more than the Series A/B Liquidation Preference Cap, then Executive shall have the right to receive a bonus equal to one times (1x) his annual base salary in effect immediately prior to the Change of Control (the “Bonus”); provided, that Executive is employed by the Company on the Closing Date (or has been terminated without Cause or has terminated his employment by the Company with Good Reason (as defined in the Employment Agreement), in each case within the three month period immediately prior to the Closing Date). In the event that the Series A Holders and the Series B Holders receive Value in the Change of Control (1) of less than the Liquidation Preference or (2) in excess of the Series A/B Liquidation Preference Cap, in each case after giving effect to any bonus payments made or to be made by Reliant pursuant to the terms of this Agreement and other similar change of control agreements or severance agreements entered into between the Company and the persons listed on Annex A attached hereto, then, in either case, Executive shall not be entitled to any Bonus.

The Bonus, if any, shall be (x) payable upon the later of (1) ten business days following the termination of Executive’s employment with the Company and (2) ten business days following the Closing Date, (y) paid in a cash lump sum and (z) shall be in addition to and not in substitution of any severance to which Executive is otherwise entitled under the terms of the Employment Agreement.

(b) Upon becoming entitled to receive the Bonus and in consideration of the Company’s agreement to pay such Bonus to Executive in accordance with Section 5(a) above, immediately prior to the consummation of the Change of Control, (i) if the Executive holds any Options, Executive shall forfeit all right to any Options held by Executive and such Options shall be deemed cancelled effective immediately prior to the Change of Control and (ii) if Executive holds Common Units, such Common Units will be redeemed for an aggregate redemption price of $1.00 by the Company and Executive shall have no further rights to such Common Units with such Common Units being deemed cancelled immediately prior to the Change of Control.

(c) In the event the Value of the Change of Control is reduced as a result of the payment made by any claims of the acquiring Person based upon (i) breaches in representations or warranties made by or on behalf of Reliant, or (ii) rights of indemnification against Reliant or its Members in connection with the Change of Control, as the case may be, (collectively, “Losses”), such that the Value (as adjusted for such Losses) received by the Series A Holders and the Series B Holders is less than the Liquidation Preference, then Executive agrees to pay to the Series A Holders and the Series B Holders on a pro rata basis the full amount of the Bonus. Bay City Capital Fund II, L.P. (“BCC Fund II”) on behalf of the Series A Holders and the Series B Holders shall re-calculate the Value after giving effect to any Losses, and in the event that the amount of such Losses reduce the Value to an amount below the Liquidation Preference, BCC Fund II shall inform Executive in writing of the total amount of such Losses and the re-calculation of Value (the “Notice”). Within 10 business days of delivery of the Notice, Executive will remit to BCC Fund II on behalf of the Series A Holders and the Series B Holders cash in the amount of 50% of the Bonus and an unsecured recourse promissory

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note in the original principal amount equal to 50% of the Bonus made in favor of BCC Fund II (not individually, but rather as disbursement agent for the Series A Holders and the Series B Holders) in form and substance reasonably satisfactory to BCC Fund II (the “Bonus Repayment Note”), which Bonus Repayment Note will provide, among others terms, for (i) interest at the rate of the prime rate as announced by Bank of America, NA payable quarterly in arrears, (ii) repayment of 50% of the original principal amount of the Bonus Repayment Note, plus any accrued but unpaid interest thereon 90 days following the date of the Note, (iii) repayment of the balance of the Bonus Repayment Note, including any accrued but unpaid interest thereon on the first anniversary of the Bonus Repayment Note and (iv) prepayment of the Bonus Repayment Note without penalty or premium upon three business days prior written notice to BCC Fund II. The Series A Holders and the Series B Holders shall be third-party beneficiaries to the provisions of this Section 5(c).

6. Vesting and Option Exercise Period.