The impulse control disorder drug nalmefene, which has previously been shown to be effective for alcohol dependence, may also be effective for pathological gambling, according to a study.

“Pathological gambling is a disabling disorder experienced by approximately 1 percent to 2 percent of adults and for which there are few empirically validated treatments,” Dr. Jon E. Grant, of the University of Minnesota Medical School, Minneapolis, and colleagues explain in the American Journal of Psychiatry.

They assessed the value of nalmefene, a long-acting opioid antagonist, in 207 pathological gamblers randomized to nalmefene at 25 mg, 50 mg or 100 mg per day or inactive placebo. Twenty-four of the 51 patients in the placebo group and 49 of the 156 subjects patients assigned to nalmefene completed the 16-week trial.

Fifty-nine percent of the subjects in the 25-mg group were rated as “much improved” or “very much improved” at the last evaluation, compared with 34 percent of those in the placebo group, Grant’s team reports.

Although 48 percent of those in the 50-mg group and 42 percent of those in the 100-mg group were considered responders, the response rate was not significantly different from that seen in the placebo group.

Most adverse events were mild to moderate, and most occurred during the first week of treatment. The most common adverse events included nausea, dizziness and insomnia.

Approximately two thirds of the patients did not complete the trial, which the researchers believe was primarily due to poor management of side effects. However, about half of the patients in pathologic gambling trials discontinue treatment, the researchers note.

SOURCE: American Journal of Psychiatry February 2006.