A new once-a-month injectable formulation of naltrexone shows promise as long-term treatment for patients with alcohol dependence, according to an article in the April 6th issue of the Journal of the American Medical Association.

Alcohol dependence is a major public health problem and is the fourth leading cause of disability worldwide, according to background information in the article. Alcohol dependence is present in approximately 4 percent of the U.S. adult population, is common among primary care patients, and may contribute to more than 100,000 preventable deaths per year.

Naltrexone has shown efficacy for alcohol dependence; however, adherence to daily oral doses can be problematic, and clinical acceptance and utility of oral naltrexone have been limited. James C. Garbutt, MD, and his American colleagues evaluated efficacy and safety of a new formulation, which releases naltrexone for 1 month following a single injection.

The 6-month, randomized, double-blind, placebo-controlled trial was conducted between February 2002 and September 2003 at 24 U.S. medical centers. Of the 899 individuals screened, 627 who were diagnosed as actively drinking alcohol-dependent adults were randomized to receive treatment and 624 received at least 1 injection. Participants received either an intramuscular injection of 380 mg long-acting naltrexone (n = 205), 190 mg long-acting naltrexone (n = 210), or a matching volume of placebo (n = 209), each administered monthly and combined with 12 sessions of low-intensity psychosocial intervention.

Compared with placebo, 380 mg long-acting naltrexone resulted in a 25-percent decrease in heavy drinking days and 190 mg naltrexone resulted in a 17-percent decrease. Sex and pretreatment abstinence each showed significant interaction with medication on treatment outcome, with men and those with lead-in abstinence both exhibiting greater treatment effects. Discontinuation due to adverse events (e.g. nausea, headache, fatigue) occurred in 14.1 percent in the 380-mg and 6.7 percent in the 190-mg group, compared with 6.7 percent in the placebo group. Overall, rate and time to treatment discontinuation were similar among treatment groups.

“In summary, the results from this trial, with one of the largest samples ever treated with a medication for alcohol dependence, indicate that long-acting injectable naltrexone is well tolerated and is associated with a significant reduction in heavy drinking in a population of actively drinking patients. The long-acting formulation has the potential to improve intervention strategies for alcohol dependence by providing a predictable pharmacological foundation for treatment. In addition to their utility for alcohol dependence, long-acting formulations may prove to be an important treatment strategy for a variety of addictive disorders,” the authors wrote.