Swift 1994: how naltrexone changes the feeling of being drunk

What they tested

Nineteen drinkers who did not have alcoholism came in on two occasions. Once they took naltrexone 50 mg by mouth and once a placebo, then drank a standard dose of alcohol meant to make them intoxicated. This is a crossover design: each person is compared with themselves, and neither they nor the researchers knew which pill came when.

Researchers measured mood, physical sensations, performance on tasks and blood alcohol over time. As a check, 12 more people took naltrexone or placebo followed by a non-intoxicating placebo drink.

What they found

Naltrexone increased some of alcohol's sedating effects and the effects that let people tell they had been drinking. It reduced alcohol's rewarding, positive effects.

It did not affect psychomotor performance, meaning tasks of coordination and reaction, and it did not change how alcohol was absorbed and broken down.

In the people given the placebo drink, naltrexone had minimal effects, so the changes came from naltrexone acting together with alcohol.

Limits

• It was a small, short lab study in people without alcohol problems, not patients in treatment.
• The abstract reports directions of effect but no sizes, so it's unclear how large the changes were.

What it means if you're considering naltrexone

The authors suggested naltrexone may cut drinking because alcohol feels more intoxicating or unpleasant and less rewarding on it. The other side of the finding matters too: naltrexone did not make people less impaired, so drinking on it is not safer for driving or other tasks.