Despite Near Overwhelming Support, Concerns About Drug’s Safety Continue
Feb. 22, 2012 -- An FDA advisory committee has reversed an earlier decision and voted overwhelmingly in favor of approving the weight loss pill Qnexa.
The vote was 20-2 in favor of Qnexa, a combination of two drugs that have long been on the market: the appetite suppressant phentermine and topiramate, which is used to treat seizures and migraines.
In August 2010, the panel rejected the drug 10-6. Although Qnexa had met FDA effectiveness requirements for weight loss drugs, clinical trials had raised concerns about its safety, specifically related to the heart and the risk of birth defects in babies whose mothers had taken it while pregnant.
In October of that year the FDA issued its negative decision in which it cited insufficient evidence of Qnexa’s safety. In response, Vivus, the manufacturer, submitted final data for a one-year extension of one of its clinical trials.
Vivus proposes to market Qnexa to people who meet the government’s definition of obesity: a BMI of 30 or greater. The labeling would advise people who lose less than 3% of their body weight in three months on the drug to stop taking it. The company will also put a plan in place to try and make sure pregnant women do not take the drug.
A final decision is expected from the FDA by April 17. Although the agency does not have to follow this recommendation, it often backs the decisions of its advisory panels.
FDA epidemiologist Suzanne Gilboa, PhD, presented information to the panel from two studies, one by Boston University and the other by the CDC, showing a small number of babies whose mothers had taken topiramate while pregnant. The only evidence of an association of birth defects was with cleft lip, Gilboa said. If the findings are true, she said, the risk for cleft lip in babies exposed to topiramate in the womb is 5 in 1,000 live births, five times the overall rate of 1 in 1,000.