The antiseizure drug topiramate, sold under the trade name Topamax, reduces body weight and blood pressure in obese patients with High Blood Pressure (hypertension) , according to the results of a study published in the American Journal of Cardiology. Adverse effects were “generally mild to moderate.”
Dr. Serena Tonstad of the University of Oslo, Norway, and colleagues randomly assigned 531 obese subjects with hypertension to receive one of two doses of topiramate or placebo (sugar pill). All of the patients were instructed to follow a standardized diet, and received exercise advice and behavioral modification through the end of the study.
The study was initially scheduled for 60 weeks, but Johnson & Johnson, the sponsor, ended the trial early to develop a new controlled-release formulation. As a result, the researchers assessed the participants after completed 28 weeks.
An average weight loss of 1.9 percent, 5.9 percent, and 6.5 percent was observed in the placebo group, the lower dose topiramate group and higher dose topiramate group, respectively.
Average decreases in diastolic blood pressure (the lower reading) for the three groups were 2.1, 5.5, and 6.3 mm Hg, respectively. Average decreases in systolic blood pressure (the upper reading) were 4.9 mm Hg in the placebo group, and 8.6 and 9.7 mm Hg in the lower and higher groups.
Diastolic blood pressure
Diastolic pressure is the force of blood in the arteries as the heart relaxes between beats. It’s shown as the bottom number in a blood pressure reading.
The proportion of subjects who lost at least 5 percent of their initial body weight was significantly greater in the two topiramate groups than in the placebo group, Tonstad’s team reports.
The most common adverse event was numbness, tingling, pricking, burning, or creeping of the skin, which occurred in 33 percent of subjects who received topiramate.
Overall, 7 percent of patients in the placebo group, 14 percent of those in the lower dose group, and 15 percent in the lower dose group withdrew from the study due to adverse events. Serious adverse events were observed in 4 percent, 5 percent, and 3 percent of the placebo, lower-dose, and higher dose groups, respectively.
The authors note in their paper that a subsequent study with the controlled-release formulation of topiramate did not show any advantages over the immediate-release formulation.
SOURCE: American Journal of Cardiology, July 15, 2005.
Revision date: June 20, 2011
Last revised: by Jorge P. Ribeiro, MD