Targeted versus daily naltrexone: secondary analysis of effects on average daily drinking

To extend our previous findings that naltrexone reduced the likelihood of heavy drinking on a given day among problem drinkers, while targeted administration reduced the likelihood of any drinking, we examined the effects of naltrexone and targeted administration on the continuous outcome of drinks/day. Because treatment response may differ by gender, we also compared the effects on this factor.

In a double-blind, placebo-controlled study, problem drinkers (n=150, 58% men) were randomly assigned to 8 weeks of treatment with naltrexone (50 mg/day) or placebo, either daily or on a targeted schedule. All subjects also received brief coping skills therapy. To complement the traditional regression analysis conducted previously, a zero-inflated Poisson regression model was used to examine the effects of medication, schedule of administration, and gender on the number of standard drinks consumed daily.

Targeted naltrexone, and to a lesser extent targeted placebo, yielded a greater reduction in daily drinking than did daily placebo, an effect that did not differ by gender and that was greater than that seen for daily naltrexone treatment. Relative to daily placebo, daily naltrexone reduced the number of drinks/day only among men, at the level of a nonsignificant trend.

Although in both genders, targeted treatments appeared to reduce the volume of drinking, treatment with targeted naltrexone was somewhat better. In contrast, heavy drinking women showed no benefit from daily naltrexone treatment. Further evaluation of the efficacy of targeted treatments and of daily naltrexone and the relationship of these treatments with gender is warranted.