After considering study data from following patients for two years, the expert panel determined that the weight-loss benefits outweighed the risks of two potential side effects: an uptick in cleft palates in children born to women who took topiramate while pregnant, and a modest increase in heart rate that could lead to heart troubles down the road. The 2010 decision was based on one year of data.
“I think this is the most efficacious drug we’ve seen,’’ said Dr. Lamont Weide, chief of diabetes and endocrinology at the University of Missouri, who voted to approve the drug.
In clinical trial data submitted to the FDA by manufacturer Vivus, patients who took higher- and lower-dose versions of the drug for two years lost between 3 percent and 10 percent of their weight on average, compared with a 2 percent loss in those who took placebos. The amount of weight lost by patients taking Qnexa led to an improvement in obesity-related health conditions, such as a reduction in high blood pressure and the diabetes marker hemoglobin A1C, and a boost in “good’’ HDL cholesterol levels.
But those on Qnexa, as well as the placebo group, began to regain lost weight after the first year of the study, so it is not known how long the effects of the drug will last.
While too few pregnancies occurred during the clinical trial to measure an increase in birth defects, a recent study on topiramate in women who took the drug during pregnancy to control seizures found that cleft lip and palate occurred in 2.9 per 1,000 births, compared with 1.6 per 1,000 births to women who stopped taking the drug before pregnancy. Other studies suggest a higher risk, which means that young women prescribed Qnexa for obesity would have to be careful to use birth control while on the drug.
Vivus also reported a slight increase in resting pulse in Qnexa users, which expert panel members said could be a signal for an increased risk of heart problems. The trials were not large enough or long enough to measure cardiac events such as heart attacks.
