Targeted Naltrexone for Problem Drinkers

This is a 12-week, placebo-controlled trial of naltrexone (50 mg orally) in 163 problem drinkers. Problem drinkers are those individuals whose drinking puts them at risk of a variety of psychosocial and medical problems, including alcohol dependence, but who are not physically dependent on alcohol. They are estimated to comprise up to 20% of the general population. The study employed a factorial design in which the effects of medication (naltrexone vs. placebo), schedule of medication administration (i.e., daily vs. targeted), and the interaction of these factors on drinking behavior were examined. Targeted administration refers to the use of medication to cope with anticipated high-risk drinking situations.

The daily monitoring using interactive voice response technology of mood, desire to drink, perceived self-efficacy, and drinking behavior will make it possible to examine in depth the processes by which the study variables exert their effects. Daily monitoring was performed using automated telephone interviews, with in-person follow-up evaluations conducted at 3 and 6 months post-treatment to provide a measure of the durability of treatment effects.

A pharmacogenetic analysis based on preliminary evidence showing that a functional polymorphism in the gene encoding the mu-opioid receptor (OPRM1) affects response to naltrexone will serve to explore an important source of variation in the response to naltrexone treatment. Exploratory analyses involving other potential genetic moderators of the response to naltrexone, such as the gene encoding the delta opioid receptor (OPRD1), will also be conducted, as will the correlation of genotype data with other phenotypes.

Careful evaluation of the study hypotheses will provide important information on the efficacy and mechanism of the effects of targeted naltrexone in problem drinkers. This study will allow us to model effects across multiple levels of analysis in an effort to understand the psychopharmacological mechanisms underlying the therapeutic effects of naltrexone in problem drinkers and to apply novel genetic findings to understanding the pharmacogenetic mechanisms underlying the therapeutic effects of naltrexone in problem drinkers.