Epilepsy drug leads to weight loss, side effects

NEW YORK (Reuters Health) - A drug approved to prevent seizures may also help obese people lose a few pounds when it's added to therapy and nutritional guidance, a new small trial suggests.

But people who took zonisamide also reported more side effects, from nausea and vomiting to anxiety and depression. And two researchers not involved in the study questioned how much the drug would actually help people in the real world.

Although zonisamide is only approved by the U.S. Food and Drug Administration for seizures, doctors can prescribe it "off-label" for non-approved purposes. Prior small trials and anecdotal evidence suggested it might help heavy people shed extra pounds.

"There is a little bit of weight loss with this drug when it is given for treatment of epilepsy," said lead researcher Dr. Kishore Gadde, from Duke University Medical Center in Durham, North Carolina.

That could be because of its effects on serotonin and dopamine, he said. Those two neurotransmitters are known to effect motivation and reward pathways in the brain, including those related to food.

Gadde said his team wanted to see if zonisamide could produce weight loss in people without epilepsy, and with the added help of a behavioral intervention.

According to disclosures published with the study, Gadde has multiple patents for zonisamide as a treatment of obesity and weight gain, and he owns equity in a company developing a combination weight-loss drug containing zonisamide.

For the new study, funded by the National Institute of Diabetes and Digestive and Kidney Diseases, Gadde and his colleagues randomly assigned 225 obese people to take either 200 or 400 milligrams of zonisamide or a drug-free placebo pill every day for one year. On top of that, all participants met regularly with a dietician and were encouraged to be more physically active.

At the outset, they had an average body mass index - a measure of weight relative to height - of 37.6. That's the equivalent of a five-foot, six-inch person weighing 233 pounds.

One year later, people assigned to the placebo had lost an average of nine pounds, and those on the lower zonisamide dose had dropped ten pounds. Participants taking the higher daily dose had the greatest average weight loss, at 16 pounds.

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Epilepsy drug leads to weight loss, side effects