Prescrire Int. 2014 Jun;23(150):150-2.
Alcohol dependence is a chronic, severe and sometimes fatal disease. Psychological and social support is a crucial element of patient management. Acamprosate and naltrexone are the drugs of choice to help patients remain abstinent, but they are only moderately effective. Nalmefene, an opioid receptor antagonist related to naltrexone, has been authorised in the European Union to help alcohol-dependent patients reduce their alcohol consumption. Nalmefene has not been compared with naltrexone or acamprosate in clinical trials. Clinical evaluation is mainly based on two double-blind, randomised, placebo-controlled trials in which nalmefene was taken « on demand » at a dose of one tablet per day. The trials lasted 6 months and included a total of 1322 patients. During an initial two-week period in which all patients received medical and psychosocial support, about one-third of patients in both trials reduced their alcohol consumption without medication. Depending on the subgroup and the trial, about one-third to one-half of patients discontinued medical treatment before the end of the study period. In both trials, patients taking nalmefene had two fewer « heavy drinking days » per month than patients in the placebo groups. However, at the end of the study, they continued to drink heavily at least one week per month on average. Daily alcohol consumption was 5 to 9 grams lower with nalmefene than with placebo. The most frequent adverse effects observed in clinical trials were insomnia, dizziness, headache and nausea, which were severe in more than 10% of patients. Other serious but less frequent adverse effects included confusion, hallucinations and dissociation, usually at the beginning of treatment. These adverse effects affected about 3% of patients treated with nalmefene, a proportion three times higher than in the placebo groups. The consequences of mixing nalmefene with large amounts of alcohol are not known. In practice, the effects of nalmefene in alcohol-dependent patients seeking to cut down or abstain are of questionable clinical relevance. Adverse effects are frequent and less well-determined than those of standard drugs. The impact of nalmefene on the complications of alcohol dependence is not known. The crucial first step in the management of alcohol-dependent patients is to establish a relationship built on trust and to provide psychological and social support. When medication is considered, it is better to choose acamprosate or naltrexone, drugs that are only moderately effective but better-assessed.