Alcohol urge and plasma beta-endorphin change after alcohol challenge with naltrexone pretreatment in social drinkers

Abstract

The authors have investigated the effect of naltrexone (NTX) on lowering the urge of alcohol drinking and the action mechanism of NTX. Fifteen healthy male social drinkers voluntarily participated. The experimental method was a double-blind, placebo-controlled cross-over design. To eliminate NTX effect, I week washout cross-over interval was taken. Subjects ingested NTX, 50 mg/day, or placebo for I week. Then, the alcohol (0.5 ml/kg) challenge test was done in the evening. Blood samples were taken immediately before drinking, at 20 min and at 60 min after alcohol drinking. Plasma beta-endorphin, plasma ACTH and serum cortisol levels were checked. Subjects completed self-report questionnaires such as the visual analog scales of drink urge and the alcohol sensation scales at regular intervals. In the case of NTX pretreatment, the subjects reported significantly (P=.013) less urge to drink alcohol on the self-reporting urge scales, especially at postdrinking 20 min and 60 min than placebo pretreatment. After alcohol challenge, the subjects reported significantly more dizziness (P=.015) in the case of NTX pretreatment, and reported less mood elevation trend, though not significant (P=.052). Basal plasma beta-endorphin levels were not different, but in the case of NTX pretreatment, the increasing degree of plasma O-endorphin during 20 min after alcohol challenge was significantly (P=.039) higher than with placebo pretreatment. This results show that the NTX reduced the urge to drink alcohol with the mechanism of partially blocking the opioid positive reward system and partially mimicking the alcohol effect. (C) 2002 Elsevier Science Inc. All rights reserved.