Naltrexone alters subjective and psychomotor responses to alcohol in heavydrinking subjects

Preclinical studies support endogenous opioid system involvement in alcohol reinforcement and consumption; however, recent clinical trials and human l aboratory studies have provided mixed findings of the effects of naltrexone (a non-selective opioid antagonist) on alcohol responses. This study used a within-subject design (n=23) to investigate naltrexone effects (0, 50 and 100 mg qd) on subjective and psychomotor responses to alcohol (none, moder ate, high) in heavy drinkers. Before alcohol administration, subjects repor ted decreased desire to drink alcohol when maintained on 50 mg compared wit h placebo naltrexone. Following alcohol administration, active naltrexone s ignificantly increased subjective ratings of sedative, and unpleasent/sick effects and decreased ratings of liking, best effects and desire to drink. Naltrexone generally did not alter subjective or objective indicators of dr unkenness. Finally, high doses of naltrexone and alcohol interacted to prod uce the greatest decreases in liking and best effects. Findings support the role of endogenous opioids as determinants of alcohol's effects and sugges ts that naltrexone may be particularly clinically useful in those treatment patients who continue to drink heavily. (C) American College of Neuropsych opharmacology. Pulished by Elsevier Science Inc.