News Release Details

SAN DIEGO--(BUSINESS WIRE)--April 16, 2008--ACADIA Pharmaceuticals Inc. (Nasdaq:ACAD), a biopharmaceutical company utilizing innovative technology to fuel drug discovery and clinical development of novel treatments for central nervous system disorders, today announced that the company will present data from its previously reported Phase II trial with pimavanserin for Parkinson's disease psychosis (PDP) at the 60th American Academy of Neurology Annual Meeting on April 16, 2008 in Chicago, Illinois.

In a poster presentation titled "A Double-Blind, Placebo-Controlled, Dose-Escalation Trial of Pimavanserin in Parkinson's Disease and Psychosis," ACADIA summarizes data from its double-blind, placebo-controlled Phase II clinical trial that was designed to evaluate the tolerability, safety, and efficacy of pimavanserin in 60 patients with PDP. The primary endpoint of the study was met as pimavanserin did not worsen parkinsonism symptoms that affect activities of daily living and motor function, as measured by the Unified Parkinson's Disease Rating Scale (UPDRS). The use of pimavanserin was shown to be safe and well tolerated. Patients treated with pimavanserin also showed improvements in psychosis scores. The data suggest that pimavanserin, a selective serotonin 5-HT2A inverse agonist that does not block dopamine D2 receptors, may provide antipsychotic benefit to patients with PDP without adversely affecting motor function. In contrast, antipsychotics used off-label for this condition are generally not well tolerated by patients with Parkinson's disease at doses required to achieve antipsychotic effects.

About Pimavanserin

Pimavanserin tartrate is a novel, potent, and selective 5-HT2A inverse agonist that ACADIA discovered and is developing as a treatment for PDP. ACADIA is currently conducting two Phase III pivotal trials in its program with pimavanserin as a treatment for PDP. ACADIA has also reported positive results from a Phase II trial in its program with pimavanserin as a co-therapy for schizophrenia.

About ACADIA Pharmaceuticals

ACADIA is a biopharmaceutical company utilizing innovative technology to fuel drug discovery and clinical development of novel treatments for central nervous system disorders. ACADIA currently has five mid-to-late stage clinical programs as well as a portfolio of preclinical and discovery assets directed at diseases with large unmet medical needs, including schizophrenia, Parkinson's disease psychosis, sleep maintenance insomnia, and neuropathic pain. 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.

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 benefits to be derived from ACADIA's preclinical and drug development programs, including pimavanserin as a treatment for PDP and as a co-therapy for schizophrenia. 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 clinical trials, and drug development and commercialization, including the uncertainty of whether results in clinical testing of pimavanserin to date will be predictive of results in later stages of development. 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, 2007 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.

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

SOURCE: ACADIA Pharmaceuticals Inc.