Re: Asset Purchase Agreement dated as of January 12, 2009, as amended (the "Agreement"), by and among Premier Research International, LLC, a Delaware limited liability company ("Premier"), Premier Research Arizona, LLC, a Delaware limited liability company and the wholly-owned subsidiary

Re:           Asset Purchase Agreement dated as of January 12, 2009, as amended (the “ Agreement ”), by and among Premier Research International, LLC, a Delaware limited liability company (“ Premier ”), Premier Research Arizona, LLC, a Delaware limited liability company and the wholly-owned subsidiary of Premier (the “ Purchaser ”), Pivotal Research Centers, Inc., a Delaware corporation (“ PRC Inc. ”), Pivotal Research Centers, LLC, an Arizona limited liability company (“ PRC LLC ,” and together with PRC Inc., the “ Sellers ”), and PHC, Inc., a Massachusetts corporation d/b/a Pioneer Behavioral Health and the parent entity of the Sellers (the “ Parent ”); Second Amendment of the Agreement

This letter agreement documents the supplemental agreements to and amendment of the Agreement with respect to the matters set forth herein.  Capitalized terms used herein and not otherwise defined shall have the meanings assigned to them in the Agreement.

1.            Earned Time-Off .  Pursuant to Section 5.4 of the Agreement, the parties agree that, except for the “Earned Time Off” costs set forth and more particularly described on Schedule 5.4 to the Agreement, which costs, in the aggregate, will not exceed the total amount set forth on Schedule 5.4 (i.e., $40,213), all employer responsibilities, costs and liabilities, including those under any severance agreements or arrangements, for any employees of the Sellers, including those terminated prior to, on or after the Closing Date shall be and remain the exclusive responsibility, cost and liability of the Sellers.  Subsequent to the date of the Agreement, Parent and the Sellers informed Premier and the Purchaser that the aggregate Earned Time Off amount is $45,154.93, for an aggregate excess amount of $4,941.93 (the “ Excess Amount ”).  Notwithstanding the foregoing, Premier and Purchaser agree to pay to the Continuing Employees each such Continuing Employee’s portion of the Excess Amount in accordance with the Schedule A attached hereto.

2.            Additional Contracts .  Pursuant to Section 3.10 of the Agreement, Schedule 3.10 is to set forth, among other things, a list of Assumed Contracts.  Subsequent to the date of the Agreement, Parent and Sellers informed Premier and the Purchaser that certain additional Contracts necessary for the conduct of the Bus