NALTREXONE-INDUCED ALTERATIONS IN HUMAN ETHANOL INTOXICATION

Objective: Outpatient clinical trials with an opioid antagonist, naltr exone, found that this agent reduces relapse drinking in abstinent alc oholics. It is unknown which aspects of intoxication may be affected b y naltrexone. The authors investigated the effects of naltrexone on se veral subjective and objective measures of ethanol intoxication Method : In a double-blind crossover study, 19 nonalcoholic drinkers received a regimen of naltrexone, 50 mg p.o., or placebo on two different occa sions, each time followed by a standard intoxicating dose of ethanol. Subjective and objective measures of intoxication including mood, phys ical sensations, performance changes, and ethanol pharmacokinetics wer e determined. As a control for naltrexone effects, 12 additional subje cts received naltrexone or placebo followed by a nonintoxicating, ''pl acebo'' dose of ethanol. Results: Naltrexone augmented certain sedativ e and discriminant effects of ethanol and reduced positive reinforcing effects without affecting psychomotor performance or ethanol pharmaco kinetics. Naltrexone had minimal effects in subjects receiving placebo ethanol. Conclusions: The data are compatible with the clinical findi ngs and suggest that the reduction in ethanol consumption by alcoholic s following naltrexone administration may occur because of greater sub jective intoxication, greater aversive effects, or less positive reinf orcement from ethanol.