Obese patients with binge-eating disorder treated with topiramate in an open-label study binged significantly less often and lost weight, according to a study by Susan L. McElroy, M.D., and her colleagues.
A previous, randomized, placebo-controlled trial of 61 patients conducted by Dr. McElroy and her coinvestigators reported that topiramate (Topamax) reduced both binge-eating behavior and body weight in obese patients suffering from binge-eating disorder (BED). That study lasted 14 weeks (Am. J. Psychiatry 2003;160:255-61).
To assess topiramate's effectiveness and tolerability over a longer period, the investigators extended the study for an additional 42 weeks in subjects who completed the first study and wanted to pursue treatment with the drug. The 42-week extension was open-label, nonrandomized, and uncontrolled (J. Clin. Psychiatry 2004;65:1463-9).
Fifteen patients who received topiramate during the controlled study and participated in the extension study showed an average drop of 4.0 binges per week, compared with their binge frequency before they started taking the drug (P < .001), and lost 14.1 kg in weight (P = .023), compared with their baseline weight. Sixteen patients who received placebo during the controlled study and participated in the extension study showed a drop of 2.5 binges per week (P < .044), compared with their baseline rate, and lost 14.5 kg (P < .002), the researchers reported.
Attrition rates, primarily due to protocol nonadherence and adverse events, were high in both the controlled and extension studies (43% and 68%, respectively).
While topiramate's mechanism of action in BED is unknown, the investigators speculated that the antiseizure medication curbs appetite and enhances satiety through glutamate receptor antagonism.
It is estimated that 1.5%-2.0% of Americans have BED, including 8%-30% of obese individuals, 70% of those in Overeaters Anonymous, and 50% of those seeking bariatric surgery.
Dr. McElroy, cautioned that because the extension trial was not a controlled randomized study, further studies are needed. He consults for Ortho-McNeil Pharmaceutical Inc., the maker of topiramate.