FOR IMMEDIATE RELEASE                                           

SUPERNUS PHARMACEUTICALS ANNOUNCES SECOND CLOSING RAISING AN ADDITIONAL $17.5 MILLION

Rockville, MD, February 21, 2006 – Supernus Pharmaceuticals, Inc., announces the closing of a second round of financing raising an additional $17.5 million. This completes the Series A funding for a total of $45 million. The company announced last month the closing of the first round of financing and the acquisition of substantially all the assets comprising the product formulation and development business of Shire Laboratories Inc., a subsidiary of Shire plc.

Investors participating in this second closing were New Enterprise Associates and Abingworth Management. “We welcome Abingworth as an additional investor and Michael Bigham, a director of Abingworth, to our Board of Directors,” said Jack A. Khattar, President & CEO of Supernus.

Supernus Pharmaceuticals, Inc. is a specialty pharmaceuticals company focused on developing products for its own portfolio and in partnership with other pharmaceutical companies, using its proven and patented technologies and product development capabilities. Among its key technologies are ProScreenÒ and OptiScreenÒ for lead selection and formulation optimization, MicrotrolÒ, SolutrolÒ and EnSoTrol®, its oral controlled release technologies, and Avert^SM, its reduced abuse potential technology.

New Enterprise Associates (NEA) is a leading venture capital firm focused on helping entrepreneurs create and build major new enterprises that use technology to improve the way we live, work and play.  Since its founding in 1978, the firm has followed the same basic principles:  support their entrepreneurs, provide an excellent return to their limited partners and practice their profession with high standards and respect.  Practicing classic venture capital for over 25 years, NEA focuses on early stage investments, playing an active role in assisting management to build companies of lasting value.  With $6 billion under management, NEA's experienced management team has invested in over 500 companies, of which more than 150 have gone public and more than 200 have been acquired.  NEA has offices in Reston, Virginia, Menlo Park, California and Baltimore, Maryland.  For additional information, visit www.nea.com.

Abingworth is a long-established venture capital firm dedicated to the life sciences sector and operates on both sides of the Atlantic. The company invests across all stages of development, including early-stage as well as public companies. Abingworth has provided backing to more than 90 life science businesses. The majority of these have gone public or have merged or been acquired. Abingworth has funds under management of about $750 million.  Founded in 1973, Abingworth has offices in London, Cambridge (UK), Menlo Park (California) and Boston.  For more information, visit www.abingworth.com.

About Supernus

Headquartered in Rockville, Maryland, Supernus Pharmaceuticals, Inc. is a specialty pharmaceuticals company that has a portfolio of proven and patented drug delivery technologies with full product development capabilities including production of GMP clinical supplies in its own facility. Supernus will focus on developing differentiated products for targeted specialty therapeutic areas on its own and in partnership with other pharmaceutical companies. For more information, visit www.supernuspharma.com.

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Contacts

Jack Khattar                                                                                          Woody Bryan

President & CEO                                                                                  VP Business Development

Supernus Pharmaceuticals, Inc.                                                         Tel: 301 838- 2681

1550 E Gude Drive                                                                                wbryan@supernus.com

Rockville, MD 20850

USA

Tel: 301 838- 2500

www.supernus.com