Sepracor, Inc. Buys ACADIA Pharmaceuticals, Inc. Shares In Partnership

SAN DIEGO, Jan. 17 /PRNewswire-FirstCall/ -- ACADIA Pharmaceuticals Inc. (Nasdaq: ACAD - News), a biopharmaceutical company utilizing innovative technology to fuel drug discovery and clinical development of novel treatments for central nervous system (CNS) disorders, today announced that Sepracor Inc. (Nasdaq: SEPR - News) has completed the second $10 million purchase of ACADIA common stock in connection with the collaboration between the two companies formed in January 2005. Sepracor's purchase was made at a price of approximately $12.29 per share, which represented a 25 percent premium to the 30-day trailing average closing price as of the one-year anniversary of the collaboration, and resulted in the issuance of 813,393 shares of ACADIA common stock.

"We are excited with the progress of our collaboration with ACADIA," said Mark H.N. Corrigan, M.D., Executive Vice President, Research and Development of Sepracor. "Their strong CNS discovery expertise and leadership position in the area of muscarinic receptor research may lead to exciting new portfolio candidates for the treatment of CNS disorders."

ACADIA and Sepracor established their research and development collaboration in January 2005 to develop new drug candidates from ACADIA's preclinical muscarinic receptor program for treatment of CNS disorders. The collaboration includes an investigation of ACADIA's selective m1 agonists for treatment of schizophrenia and other neuropsychiatric disorders. Muscarinic receptors respond to the neurotransmitter acetylcholine. Compounds that selectively act on these receptors may have utility in the treatment of CNS disorders. The collaboration also includes an option for Sepracor to select a preclinical compound from ACADIA's 5-HT2A program for use in combination with LUNESTA(TM) brand eszopiclone, Sepracor's insomnia drug, for sleep-related indications. 5-HT2A antagonists have been shown in clinical studies to affect sleep architecture, resulting in extended periods of slow-wave sleep, which may have a positive effect on sleep quality.

"Sepracor's high-quality research and development team and the complementary nature of our organizations make Sepracor an ideal partner for ACADIA," said Mark R. Brann, Ph.D., President and Chief Scientific Officer of ACADIA. "We are gratified by the confidence that Sepracor has expressed in ACADIA and our collaboration."

In connection with the collaboration, Sepracor has purchased an aggregate of $20 million of ACADIA common stock. Pursuant to the collaboration, Sepracor is also providing ACADIA with research funding over a three-year term, and if certain conditions are met, will be required to pay ACADIA milestone payments as well as royalties on worldwide product sales. Assuming the successful development of a single product in the muscarinic program, Sepracor will be required to pay ACADIA up to $40 million in aggregate payments plus applicable royalties. In addition, should the collaboration successfully develop a combination product with LUNESTA, Sepracor will also be obligated to pay ACADIA up to approximately $35 million in aggregate payments plus applicable royalties.

About ACADIA Pharmaceuticals

ACADIA is a biopharmaceutical company utilizing innovative technology to fuel drug discovery and clinical development of novel treatments for CNS disorders. ACADIA currently has four drug programs in clinical development as well as a portfolio of preclinical and discovery assets directed at large unmet medical needs, including schizophrenia, Parkinson's disease, neuropathic pain, and glaucoma. All of the drug candidates in ACADIA's product pipeline emanate from discoveries made using its proprietary drug discovery platform. ACADIA's corporate headquarters is located in San Diego, California and it maintains research and development operations in both San Diego and Malmo, Sweden.

About Sepracor

Sepracor Inc. is a research-based pharmaceutical company dedicated to treating and preventing human disease through the discovery, development and commercialization of innovative pharmaceutical products that are directed toward serving unmet medical needs. Sepracor's drug development program has yielded an extensive portfolio of pharmaceutical compound candidates with a focus on respiratory and central nervous system disorders. Sepracor's corporate headquarters are located in Marlborough, Massachusetts.

Forward-Looking Statements

Statements in this press release that are not strictly historical in nature are forward-looking statements. These statements include but are not limited to statements related to potential milestone and royalty payments under the collaboration, the research and development of drug candidates under the collaboration, future funding of the collaboration research, the safety, efficacy and potential benefits of any compounds discovered or developed under the collaboration, the progress and timing of ACADIA's drug discovery and development programs and related trials, and the potential benefits to be derived from ACADIA's technology or discovery and development candidates. These statements are only predictions based on current information and expectations and involve a number of risks and uncertainties. Actual events or results may differ materially from those projected in any of such statements due to various factors, including the risks and uncertainties inherent in drug discovery, development and commercialization, collaborations with others, and litigation. For a discussion of these and other factors, please refer to ACADIA's annual report on Form 10-K for the year ended December 31, 2004 filed with the United States Securities and Exchange Commission as well as other subsequent filings with the Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. All forward-looking statements are qualified in their entirety by this cautionary statement and ACADIA undertakes no obligation to revise or update this press release to reflect events or circumstances after the date hereof.

Lunesta is a trademark of Sepracor Inc.

Contacts: ACADIA Pharmaceuticals Inc. Lisa Barthelemy, Director, Investor Relations Thomas H. Aasen, Vice President and Chief Financial Officer (858) 558-2871

Source: ACADIA Pharmaceuticals Inc.