EFFECTS OF NALTREXONE PRETREATMENT ON THE SUBJECTIVE AND PERFORMANCE EFFECTS OF ETHANOL IN SOCIAL DRINKERS

Clinical trials suggest that opioid antagonists may be effective in th e treatment of alcoholism. For example, two recent clinical trials rep orted that alcoholics treated with the opioid antagonist naltrexone ex hibited higher abstinence rates, decreased craving and a decrease in t he amount of alcohol consumed if drinking occurred. The present study examined the hypothesis that naltrexone pretreatment would attenuate t he behavioral responses to an acute dose of ethanol in normal, healthy social drinkers. Thirteen healthy male and female social drinkers par ticipated in a sig-session, double-blind, placebo-controlled, crossove r design study. On each session, subjects Ingested a capsule containin g naltrexone (25 or 50 mg) or placebo and one hour later consumed a be verage containing ethanol (0.5 g/kg) or placebo. For three hours after the beverage was consumed, breath alcohol levels were measured and su bjects completed standardized subjective effects questionnaires and pe rformance tasks at regular intervals. Ethanol atone produced its proto typic effects, including positive subjective responses such as euphori a and increased ratings of overall liking, as web as increased ratings of confusion. Ethanol also impaired performance on a verbal recall ta sk. Naltrexone alone produced few subjective effects and did not impai r psychomotor or verbal recall performance. Contrary to our hypothesis , pretreatment with naltrexone did not alter the positive subjective e ffects, or any other effects, of ethanol. Further research is needed t o determine the influence of factors such as baseline level of ethanol consumption or duration of naltrexone treatment on the interaction be tween ethanol and the endogenous opioid system.