Naltrexone is a long-acting opioid antagonist that binds competitively to receptors in the central and peripheral nervous systems. Its exact mechanism of action in the treatment of alcohol dependence is unknown. The reinforcing effect of alcohol consumption is thought to be related to stimulation of the endogenous opioid system, and naltrexone may work by interacting with this system.1
To prevent serious withdrawal symptoms, prescribers must ensure patients are opioid-free before initiating therapy. Patients should be warned not to use opioids (eg, cough and cold remedies or anti-diarrhoeals) during treatment with naltrexone.1
The efficacy and safety of naltrexone in the treatment of alcohol dependence was assessed in a systematic review of 50 double-blind randomised controlled trials (n=7793) that compared naltrexone or nalmefene with placebo or active control. Naltrexone reduced the risk of heavy drinking by 17% compared with placebo (RR 0.83, 95% CI 0.76–0.90). In addition, drinking days were reduced by approximately 4% (mean difference –3.89%; 95% CI –5.75 to –2.04).2
In a meta-analysis of seven randomised controlled trials, naltrexone was superior to placebo in the maintenance of alcohol abstinence. Significantly fewer episodes of relapse were observed with naltrexone than placebo, and significantly more patients in the naltrexone group remained abstinent following 12 weeks of treatment compared with the control group.3
Adverse events related to naltrexone were mainly gastrointestinal and sedative effects. In the meta-analysis, there was no significant difference between naltrexone and placebo in the number of patients with at least one adverse event, or the number of patients who discontinued treatment owing to an adverse event.2,3
- Adepend Summary of Product Characteristics, December 2011.