A widely prescribed epilepsy drug that has shown promise for helping obese people lose weight is also helping them continue to keep the pounds off.

Obese people who lost weight by restricting calories continued to lose weight after taking Topamax and were more likely to keep it off long term, in a study reported by researchers in Denmark.

Ten months into the study, dieters who took Topamax (search) had lost almost twice as much weight as those taking placebo pills, even though both groups initially lost similar amounts of weight by restricting calories before beginning the medication.

The Danish study ended early because Topamax manufacturer Johnson and Johnson Pharmaceuticals is developing a time-release version of the drug that it hopes will minimize side effects and be more appropriate for dieters.

“The initial data on Topamax are very impressive,” weight loss specialist Samuel Klein, MD, tells WebMD. “It does appear to be more effective than the currently available drug therapies in terms of taking the weight off and keeping it off. But you have to remember that these are preliminary studies.”

Dieters Kept Losing

The study included obese people who lost 8 percent or more of their body weight by restricting daily calories to about 800-1,000 calories per day for two months. At the end of the two-month period, the successful dieters were started on either low or high doses of Topamax or placebo pills. All the dieters also underwent lifestyle modification counseling designed to promote healthy eating habits.

At the end of week 44, dieters taking low-dose Topamax had lost 15 percent, and high-dose Topamax dieters lost 17 percent of their initial body weight, compared with a 9 percent weight loss among dieters who took a placebo. Dieters taking the epilepsy drug continued to lose weight over the course of the study, while those taking placebos did not.

The most common side effect seen among Topamax dieters was paresthesia, a tingling, “pins and needles” sensation in the extremities, which occurred in 46 percent of patients taking the lower dose of the drug and 73 percent of those taking the higher dose.

Topamax use has also been linked to problems with memory. In this study, 18 percent of dieters taking higher doses of the drug reported memory problems, compared with 14 percent of those taking the lower dose and 6 percent of those taking placebo. The study is reported in the October 2004 issue of the journal Obesity Research.

A New Beginning

Klein says Topamax is one of several promising medications poised to usher in a new era of drug treatment for obesity.

The experimental weight loss drug Acomplia made headlines last week when researchers reported that it also helped dieters lose weight and keep it off long term. There are also reports that the drug, which targets the brain’s pleasure center, may prove to be effective for smoking cessation. French pharmaceutical firm Sanofi-Aventis reportedly plans to seek FDA approval for Acomplia by the middle of next year.

“I think this signals the beginning of a new surge of medications for weight loss that address unique neurological pathways in the brain,” says Klein, who directs the Washington University Center for Human Nutrition. “That is certainly exciting.”

By Salynn Boyles, reviewed by Brunilda Nazario, MD

SOURCES: Astrup, A. Obesity Research, October 2004; vol 12: pp 1658-1669. Arne Astrup, professor of human nutrition, Royal Veterinary and Agricultural University, Copenhagen, Denmark. Samuel Klein, MD, director, Washington University Center for Human Nutrition, St. Louis.