Background: A 12-week, multicenter, double-blind, randomized, parallel-group clinical trial to compare naltrexone and placebo was carried out to determine the efficacy, safety, and tolerability of naltrexone together with a psychosocial intervention in the treatment of alcoholism.
Methods: A total of 202 alcohol-dependent patients were assigned to 12 weeks' treatment with either naltrexone or placebo. The relapse rate was evaluated by means of intention-to-treat analyses. Alcohol consumption, craving, adverse events, and changes in the biochemical markers of heavy drinking and possible toxicity were evaluated in the 192 patients who were considered to be assessable.
Results: The survival function for patients who were treated with naltrexone was significantly better than that of the patients who were treated with placebo (Kaplan-Meier log rank = 4, df = 1, p < 0.05). In addition, 7.9% of patients who were treated with naltrexone relapsed as compared with 18.8% of those who received placebo [chi = 5.89, df = 2, p = 0.050]. In comparing naltrexone with placebo-treated patients, the most common adverse events were abdominal pain [8.6% vs. 1%; (chi = 6.1, df = 1, p < 0.05)] and headache [7.5% vs. 1% (chi = 5.1, df = 1, p < 0.05)].
Conclusions: Naltrexone was well-tolerated, as the rate of adverse events was low, and safe, as it did not interfere with the normalization of biochemical markers of heavy drinking or alter liver function markers. Naltrexone seemed to reduce relapse rate to heavy drinking, but we found no differences in other alcohol consumption variables between naltrexone- and placebo-treated groups. Although the naltrexone group showed a tendency to consume fewer drinks per drinking day and had a longer time to first drink, differences were not statistically significant.