BEHAVIORAL-RESPONSES TO ETHANOL IN LIGHT AND MODERATE SOCIAL DRINKERSFOLLOWING NALTREXONE PRETREATMENT

The opioid antagonist naltrexone has been shown to be effective in the treatment of alcoholism, possibly by dampening the subjective effects of ethanol. However? naltrexone does not consistently attenuate the e ffects of ethanol in social drinkers in laboratory-based challenge stu dies. In the present study, 25 healthy volunteers, who were either lig ht drinkers (mean = 3 drinks per week) or moderate drinkers (mean = 16 drinks per week), participated in six evening sessions. At each sessi on, subjects ingested a capsule containing naltrexone (25 or 50 mg) or placebo, and 1 hr later they consumed a beverage containing ethanol ( 0.25 g/kg, equivalent to about two standard alcoholic drinks) or place bo. Subjects received all combinations of pretreatments and beverages. They completed self-report mood questionnaires and psychomotor tests at regular intervals. This low dose of ethanol produced modest but sig nificant effects on self-report measures such as ratings of feeling a drug effect and of liking the drug effect. However, naltrexone (25 or 50 mg) pretreatment had no dampening effect on subjects' responses to ethanol. These results indicate that acute doses of naltrexone that ar e effective when administered chronically to alcoholics do not attenua te the acute effects of a low dose of ethanol in non-problem drinkers. (C) 1997 Elsevier Science Ireland Ltd.