Study of Sustained Efficacy and Tolerability of Vivitrex — Naltrexone Long-Acting Injection — after 18 Months of Treatment Presented At APA

Business Wire, May 23, 2005

CAMBRIDGE, Mass. -- --Vivitrex(R) Demonstrated a Long-term Treatment Effect in Conjunction with Counseling in Alcohol Dependent Patients --

Alkermes (Nasdaq: ALKS) today announced positive results from the Phase III, open-label, 12-month extension study of Vivitrex(R) (naltrexone long-acting injection) in alcohol dependent patients. Findings from the study, presented today at the American Psychiatric Association (APA) Annual Meeting in Atlanta, Georgia, showed that Vivitrex and counseling led to a sustained reduction in heavy drinking over an 18-month treatment period among patients who had completed the six-month Phase III efficacy trial ("main trial") and enrolled in an open-label 12-month extension study. Over eighty-five percent of patients who completed the main trial chose to participate in the extension study.

"Alcohol dependence is a chronic, relapsing disease. We were pleased to see that in this study, Vivitrex led to a sustained reduction in heavy drinking over an extended treatment period," stated David Gastfriend, M.D., Vice President of Medical Affairs at Alkermes. "These results complement the data from our Phase III efficacy study and reinforce our belief that pharmacotherapy has the potential to advance the standard of care for alcohol dependence."

Vivitrex Phase III Extension Study Results

The results of the extension study were presented in a poster entitled "Durability of Effect of Long-Acting Injectable Naltrexone." This Phase III, open-label extension study was designed to characterize outcomes of patients who received long-term treatment with Vivitrex following completion of the main trial. The results of the main trial were recently reported in the Journal of the American Medical Association(1). The objectives of the extension study were to examine the durability of the treatment effect and to continue the evaluation of the tolerability of Vivitrex administered by intramuscular injection once-monthly in adults with alcohol dependence. The trial included 332 patients who had completed the six-month main trial. Patients who received Vivitrex 380 mg (N = 115) or Vivitrex 190 mg (N = 102) during the main trial were assigned the same dose in the extension study. Patients who received a placebo injection in the main trial received either Vivitrex 380 mg (N = 60) or Vivitrex 190 mg (N = 55), based on the volume of placebo injection administered in the main trial.

Of the 332 patients who chose to participate in the extension study, 140 (42%) patients received all study injections, and 109 (78%) patients who completed the extension study chose to participate in a further continuation phase.

Key findings from this open-label study included:

--The subgroup of patients who continued on active treatment with Vivitrex 380 mg showed a sustained reduction in levels of heavy drinking over the 12-month extension study. For this subgroup, the median number of heavy drinking days over the six months of Vivitrex treatment in the main trial was similar to the median number of heavy drinking days over the 12 months of Vivitrex treatment in the extension study (2.6 days per month and 1.6 days per month, respectively). Heavy drinking is defined as five or more drinks per day for men and four or more drinks per day for women.

--Patients treated with placebo injection and counseling in the main trial who switched to Vivitrex 380 mg in the extension study showed a reduction in the number of heavy drinking days, from 5.2 days per month over six months of placebo treatment in the main trial to 1.8 days per month over 12 months of Vivitrex treatment in the extension study.

--Vivitrex was generally well tolerated over the 18-month period. The most common adverse events observed during the extension study were headache, nasopharyngitis, and upper respiratory tract infections.

Three additional posters are being presented on results from the Vivitrex clinical development program during the APA meeting:

--"Effects of Lead-in Drinking/Treatment Goal with Long-acting Naltrexone" will be presented Monday, May 23, from 3:00 pm - 5:00 pm by Stephanie O'Malley, Ph.D., Professor of Psychiatry and Director of the Division of Substance Abuse Research at Yale School of Medicine.

--"Correlation of Serum Gamma-Glutamyl Transferase with Alcohol Consumption" will be presented Monday, May 23, from 3:00 pm - 5:00 pm by Peter Martin, M.D., Professor of Psychiatry, Pharmacology Director of Division of Addiction Medicine at Vanderbilt University Medical Center.

--"Effect of Long-Acting Injectable Naltrexone on Quality of Life," will be presented Thursday, May 26, from 12:00 pm - 2:00 pm by Henry Kranzler, M.D., Professor of Psychiatry, Associate Scientific Director of the Alcohol Research Center, and Assistant Dean for Clinical Research at University of Connecticut School of Medicine.

About Alcohol Dependence

In the U.S., approximately 18 million people are dependent on or abuse alcohol(2) and an estimated 2.3 million adults seek treatment each year(3). Even among individuals currently seeking treatment, the majority relapse(4). Taking prescribed medication, an important determinant in therapeutic outcomes(5), is particularly challenging for patients with addictive disorders such as alcohol dependence(6). Alcohol is causally related to more than 60 medical conditions, including heart disease, liver disease, infectious disease, and cancer(7)(8), and contributes to more than 100,000 deaths in the U.S. each year(9). In addition, alcohol abuse and dependence accounts for approximately $134 billion in lost earnings annually(10).