Opioid antagonists are effective treatments for alcohol and other drug (e.g., heroin) dependence, presumably because of their effects on brain reward pathways. In this industry-funded multicenter randomized trial, researchers tested nalmefene, an investigational opioid antagonist, in 207 adults with DSM-IV diagnoses of pathological gambling. Severity of gambling was measured by a symptom score that included distress due to gambling and time spent either gambling or occupied with urges to gamble.
Two thirds of subjects dropped out of the study before the 16th week, mainly because of adverse events and loss to follow-up. Dropouts were less common in the placebo group than in the nalmefene group. In analyses that included subjects with at least two post-randomization observations, those assigned to nalmefene had significantly lower severity of pathological gambling at 16 weeks than those assigned to placebo. The most common adverse events (nausea, insomnia, and dizziness) occurred more often in subjects randomized to nalmefene than in those randomized to placebo.
Nalmefene might reduce the severity of pathological gambling, at least in people who don’t experience substantial side effects and who continue to take it. Perhaps lower doses or other opioid antagonists will be better tolerated but will still affect the reward pathway enough to improve symptoms.
Reference:
Grant JE et al. Multicenter investigation of the opioid antagonist nalmefene in the treatment of pathological gambling. Am J Psychiatry 2006 Feb; 163:303-12.