Doty 1997: naltrexone didn't dull two drinks in social drinkers

What they tested

Twenty-five healthy volunteers came to six evening sessions. Each time they swallowed a capsule of naltrexone 25 mg, naltrexone 50 mg or a placebo, and an hour later drank either alcohol (0.25 g/kg, about two standard drinks) or a placebo drink.

Over the six sessions everyone got every combination. They filled in mood questionnaires and did psychomotor tests, which measure coordination and reaction, at regular intervals.

What they found

The low dose of alcohol had modest but significant effects on self-reported measures, such as feeling a drug effect and liking that effect.

Naltrexone at 25 or 50 mg had no dampening effect on people's responses to the alcohol.

The authors concluded that single doses of naltrexone that work when taken daily by people with alcoholism do not blunt the immediate effects of a low dose of alcohol in people without drinking problems.

Limits

• The volunteers were light or moderate social drinkers, not people with alcohol problems.
• It tested a single dose of naltrexone before a small amount of alcohol, not daily use or heavier drinking.
• It was a small lab study.

What it means if you're considering naltrexone

Not everyone notices a change in how alcohol feels on naltrexone. This study found no difference after about two drinks in non-problem drinkers, while a study of heavy drinkers (McCaul 2000) did find changes. A first drink that feels normal doesn't, on its own, say whether the medicine will help someone who drinks heavily.