Maisel 2013: naltrexone vs acamprosate, and when each helps most

What they tested

The authors pooled 64 randomized, placebo-controlled, English-language trials of oral naltrexone or acamprosate completed between 1970 and 2009. A meta-analysis combines the results of many trials to get a clearer overall answer. Because most trials compared one drug with placebo, the comparison between the two drugs is indirect.

They also tested whether the way each drug was used changed its effect: requiring abstinence before starting, detox before starting, the goal of treatment, how long treatment lasted and the dose.

What they found

Acamprosate had a significantly larger effect than naltrexone on keeping people abstinent. Naltrexone had a larger effect than acamprosate on reducing heavy drinking and craving.

For naltrexone, trials that required people to be abstinent before starting were linked to larger effects compared with placebo, both for staying abstinent and for cutting heavy drinking.

For acamprosate, detox before starting the medicine was linked to better abstinence results compared with placebo.

The authors' summary: acamprosate is slightly more effective for promoting abstinence, and naltrexone slightly more effective for reducing heavy drinking and craving.

Limits

• The comparison between the two drugs is indirect, since it rests mostly on each drug's results against placebo in separate trials.
• Only English-language trials were included.
• The findings about abstinence or detox before treatment come from comparing trials with different designs, which shows a link, not proof that those steps cause better results.

What it means if you're considering naltrexone

This review is the source of a common shorthand the site's guides use: naltrexone for cutting down, acamprosate for staying sober. The guides treat it as a tilt, not a rule, because trials that compared the two drugs directly found little difference.

For someone whose main aim is fewer heavy drinking days, the review leans toward naltrexone. For someone set on full abstinence, acamprosate had a slight edge in these trials.