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Results Demonstrate Co-Administration of indiplon and Alcohol Has Little Or No Additive Effect on indiplon When Taken Together

SAN DIEGO, May 20 /PRNewswire-FirstCall/ -- Neurocrine Biosciences, Inc. (Nasdaq: NBIX) announced today that Neurocrine and Clinical Investigators from the Company's indiplon clinical development program presented the first of two abstracts reporting data from a Phase I pharmacokinetic (PK) clinical trial at the American Psychiatric Association (APA) Meeting in San Francisco, May 17-22, 2003.

The first abstract presented late Monday, May 19, 2003 describes the effect of alcohol on the pharmacodynamics (PD) and pharmacokinetics (PK) of a single dose of indiplon (10 mg.) in a randomized, placebo-controlled, double blind, three-way crossover Phase I clinical study in ten healthy adult volunteers. PD assessments of performance were measured by the four validated measurements of residual impairment, Visual Analogue Scale (VAS), Symbol Copy Test (SCT), Digital Symbol Substitution Test (DSST), and Psychomotor Vigilance Reaction Task (PVT). Results demonstrated that the pharmacokinetics (PK) of indiplon was not affected by alcohol. The absence of any significant PK interaction was not unexpected as different pathways metabolize indiplon and alcohol. However, the findings of little or no additive interaction when the combination of alcohol and indiplon was compared with alcohol or indiplon alone on accepted measures of performance, subjective sedation, or reaction time, is in contrast to previously published studies when alcohol is combined with other sedative hypnotics. There was also no additional effect on the incidence of side effects in the combination compared with either compound given alone.

The second abstract entitled Efficacy of Indiplon Solution in a Model of Transient Insomnia explores the efficacy and tolerability of indiplon in healthy adults will be presented on Thursday, May 22, 2003 from 12:00 PM to 2:00 PM PDT at the APA meeting.

Neurocrine is conducting one of the most comprehensive clinical programs in insomnia to address the multiple needs of younger and older adult patients with insomnia such as sleep initiation, sleep maintenance, and long-term administration. Neurocrine has initiated and is completing all of its multiple Phase III safety and efficacy trials to support a New Drug Application (NDA) registration expected in early 2004 for indiplon for multiple indications associated with insomnia.

indiplon is a unique non-benzodiazepine sedative hypnotic that acts on a specific site of the GABA-A receptor. It is through this mechanism that the currently marketed non-benzodiazepine therapeutics also produce their sleep- promoting effects. However, indiplon has been shown to be more potent than the currently marketed non-benzodiazepines at the specific subtype of receptors within the brain believed to be responsible for promoting sleep.

Insomnia is a prevalent neurological disorder in the United States, with more than one-half of the adult population reporting trouble sleeping a few nights per week or more, according to the National Sleep Foundation's (NSF) Sleep in America Poll 2002. Approximately 35% of the adult population reports that they have experienced insomnia every night or almost every night within the past year. Despite this widespread prevalence, insomnia remains a disorder with high unmet medical needs, including the ability to maintain sleep throughout the night without next-day residual effects.

Neurocrine Biosciences, Inc. is a product-based biopharmaceutical company focused on neurological and endocrine diseases and disorders. Our product candidates address some of the largest pharmaceutical markets in the world including insomnia, anxiety, depression, diabetes, multiple sclerosis, irritable bowel syndrome, eating disorders, pain, autoimmunity and certain female and male health disorders. Neurocrine Biosciences, Inc. news releases are available through the Company's website via the Internet at http://www.neurocrine.com .

In addition to historical facts, this press release contains forward- looking statements that involve a number of risks and uncertainties. Among the factors that could cause actual results to differ materially from those indicated in the forward looking statements are risks and uncertainties associated with Neurocrine's indiplon development program and business and finances including, but not limited to, risk that indiplon will not successfully proceed through Phase III clinical trials or that Phase III clinical trials will not show that it is safe and effective in treating humans; determinations by regulatory and governmental authorities; our reliance on corporate collaborators for commercial manufacturing and marketing and sales activities; uncertainties relating to patent protection and intellectual property rights of third parties; impact of competitive products and technological changes; availability of capital and cost of capital; and other material risks. A more complete description of these risks can be found in the Company's Form 10K for December 31, 2002 and the Company's most recent report on Form 10Q. Neurocrine undertakes no obligation to update the statements contained in this press release after the date hereof.

SOURCE Neurocrine Biosciences, Inc.