Johnson 2007: topiramate for alcohol dependence in 371 people

What they tested

Adults with alcohol dependence were randomly given topiramate, up to 300 mg a day (183 people), or a placebo, a dummy pill (188 people), for 14 weeks. Neither they nor the staff knew who had which. Everyone also had a weekly session aimed at helping them take their medicine.

The main measure was the percentage of heavy drinking days, reported by participants. The team also looked at days abstinent, drinks per drinking day, and a blood test for alcohol use (gamma-glutamyltransferase, or GGT).

What they found

Counting every dropout as a return to their starting level of drinking, topiramate beat placebo on heavy drinking days, with a mean difference of 8.44%. A second, prespecified analysis found a larger difference of 16.19% and showed topiramate also did better on every other drinking measure.

Several side effects were more common on topiramate than placebo: tingling or numbness (paresthesia) in 50.8% vs 10.6%, changes in taste in 23.0% vs 4.8%, loss of appetite in 19.7% vs 6.9%, and difficulty concentrating in 14.8% vs 3.2%.

The authors called topiramate a promising treatment for alcohol dependence.

Limits

• There was no naltrexone group, so the trial can't say whether topiramate works better or worse than naltrexone.
• It lasted 14 weeks, and the main outcome relied on what people reported about their own drinking.
• The size of the benefit depended a lot on how dropouts were handled: 8.44% in the stricter analysis versus 16.19% in the other.

What it means if you're considering naltrexone

For someone comparing options, this trial shows topiramate can reduce heavy drinking, but its side effects, especially tingling and trouble concentrating, were frequent. Naltrexone is FDA-approved for alcohol use disorder; topiramate is used off-label.

Because the two drugs weren't compared directly here, the choice between them rests on other trials, side effects and a person's own health.