EXHIBIT 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them a Statement on Schedule 13G (including amendments thereto) with regard to the common stock of New River Pharmaceuticals Inc., and further agree that this Joint Filing Agreement be included as an exhibit to such joint filings. In evidence thereof, the undersigned, being duly authorized, hereby execute this agreement as of the 16th day of February, 2006.

Date: February 16, 2006	/s/Randal J. Kirk
	Randal J. Kirk
Date: February 16, 2006	RJK, L.L.C.
	By:	/s/Randal J. Kirk
		Randal J. Kirk
		Manager
Date: February 16, 2006	NEW RIVER MANAGEMENT II, LP
	By:	Third Security Capital Partners, LLC, its general partner
	By:	Third Security, LLC, its managing member
	By:	/s/Randal J. Kirk
		Randal J. Kirk
		Sole Member

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