DrugAbuse Sciences, Inc. Phase II Clinical Trial of Depot Naltrexone -NALTREL- Shows Sustained Opiate Blockade Over Six Weeks

Business Wire, Feb 7, 2001

Business Editors/Health and Medical Writers

BIOWIRE2K

LOS ALTOS, Calif.--(BW HealthWire)--Feb. 7, 2001

Today Dr. George Bigelow from Johns Hopkins University School of Medicine presented results of a clinical trial examining the opiate blocking properties of depot naltrexone, a product candidate of DrugAbuse Sciences, Inc. (DAS) of Los Altos, California and Paris, France. The one-day conference in Brussels entitled Alcohol and Drugs of Abuse: Genetics, Neurobiology, Clinical Definitions and Endpoints, Future Therapies, was attended by drug abuse researchers and policy makers from the US and Europe.

The phase II clinical trial, conducted at Johns Hopkins University School of Medicine, Behavioral Pharmacology Research Unit, involved subjects who had previously used heroin, but were not currently addicted. Investigators compared the ability of two doses of depot naltrexone (NALTREL(TM)) to block the effects of hydromorphone, an opiate similar in effects to heroin.

DrugAbuse Sciences' depot naltrexone is designed to be administered using a simple intramuscular injection only once a month. In this double-blind phase II clinical trial, fifteen heroin users were randomized to one of two doses of depot naltrexone. Following a single dose of depot naltrexone subjects were administered, under double-blind conditions, weekly subcutaneous doses of either hydromorphone (an opiate drug) or a placebo challenge for six weeks. Preliminary analysis of the trial showed that both doses of depot naltrexone produced statistically significant blockade of opiate effects for six weeks as measured by subjective rating scales and measurement of pupil size. In this trial, depot naltrexone was well tolerated.

"Our once a month depot naltrexone medication is designed to improve naltrexone's clinical usefulness by eliminating the need for patients to take tablets on a daily basis, potentially offering a convenient therapy for opiate addiction," said Elizabeth Greetham, DrugAbuse Sciences CEO. "We are very pleased with the results of this trial and are moving forward with development of depot naltrexone in this patient population."

Naltrexone is commercially available as an oral tablet dosage form. Its clinical usefulness in treating heroin addiction has been limited because the tablet must typically be taken daily for a period of months to be effective in maintaining abstinence. Failure to comply with the prescribed dosing schedule can increase the risk of relapse.

DrugAbuse Sciences, the first biotechnology company focused solely on developing therapies for treatment of substance abuse, has a portfolio of six product candidates. DAS launched oral naltrexone tablets in the U.S. in December 2000. Naltrexone is indicated for use in the treatment of alcohol dependence and for the blockade of exogenously administered opioids. Naltrexone is contraindicated in patients receiving opioid analgesics, currently dependent upon opioids, in acute opioid withdrawal, in anyone who has failed a naloxone challenge test or has a positive urine screening test for opioids, in anyone with a history of sensitivity to naltrexone, or in anyone with acute hepatitis or liver failure. U.S. phase III clinical trials are ongoing to further determine the depot naltrexone's potential efficacy and safety for treatment of alcoholics. In addition to its depot naltrexone product candidate, DAS is developing BUPREL(TM), a once-per-month, injectable, sustained-release formulation of buprenorphine. BUPREL is intended to potentially provide an alternative treatment to methadone or oral buprenorphine for heroin dependent patients. For treatment of cocaine abusers, DAS is developing DAS-431(TM), a dopamine (D1) receptor agonist.

DrugAbuse Sciences, Inc. is dedicated to being the technology and education leader in providing products for substance abuse treatment and partnering with the caregiver. A DrugAbuse Sciences, Inc. supported web site, www.AlcoholMD.com, was launched in 2000. AlcoholMD.com(TM) is designed to provide clinicians, patients and their families, recovering alcoholics, kids and educators with easy access to information and services related to alcohol abuse treatment and care with a focus on the science behind addiction and treatment.

This press release contains forward-looking statements that involve risks and uncertainties, including statements regarding the company's (i) technologies, product candidates, intents and goals, and (ii) research and development plans. Forward-looking statements reflect DAS's current estimates with respect to future events. Actual results may vary materially and adversely from those anticipated, believed, estimated, or otherwise indicated. There can be no assurance that the company will have sufficient funding to develop its product candidates, that any product candidate under development will be fond

effective, safe, approved, or be manufactured in sufficient quantities at an economical cost, or that any product will not infringe the proprietary rights of third parties or will result, if approved, in significant revenues and market share.