Objective
Naltrexone is an effective treatment for alcohol dependence, with studies showing that it reduces alcohol consumption and craving, prevents relapse and promotes abstinence. However not all drinkers experience benefits. The aim of this study was to examine participant characteristics that might predict treatment success, thus identifying those likely to respond best to naltrexone.

Methods
A total of 100 alcohol-dependent participants were prescribed naltrexone and offered cognitive-behavioural therapy for 12 weeks. Comparisons were made according to genetic status, referral source and goal of treatment. Outcome measures included changes in self-reported and objective (GGT and MCV) indicators of alcohol use, time to first relapse and craving.

Results
Overall, naltrexone treatment produced significant decreases in self-reported and objective indicators of alcohol use and craving from baseline, particularly during the first two months of treatment. Participants remained in treatment for an average of 10 weeks. Side-effects were minor and resolved quickly. Self-reported alcohol use decreased from 1085 grams/week to 45 at the end of treatment. MCV decreased from 95 to 93 femtolitres, and GGT from 70 to 48 units/litre.

There was no evidence of a significant association between genotype and treatment success. However, greater decreases in alcohol use measures were observed in participants with both abstinence and controlled drinking goals, post-detoxification patients and those referred from the community. A greater number of days abstinent prior to treatment was associated with better outcomes.

Conclusions
The results of this study indicate that naltrexone is an effective treatment for alcohol dependence, with significant decreases in self-reported and objective indicators of alcohol use. Genotype was not a predictor of success, but abstinence prior to treatment did show an association.