An investigational diet drug is getting media attention from celebrity doctor Dr. Oz as the “New Silver Bullet for Weight Loss,” but the Food and Drug Administration (FDA) has yet to approve the drug based on health concerns including heart problems and birth defects.
The new drug, made by Vivus, is Qnexa, a combination of phentermine and topiramate. Phentermine is a stimulant that is FDA approved as a diet pill to aid in weight loss. It was once part of the wonder drug fen-phen, which was banned in 1997 for damaging heart valves. Tropiramate, also known by the brand Topamax, is approved for the treatment of epilepsy and migraine headaches.
Researchers found that tropiramate when used with phentermine enhances phentermine’s appetite suppressing abilities significantly enough to cause obese patients to lose a significant amount of weight in a relatively short time without feeling hungry or deprived of food. Vivus presented these findings to the FDA more than two years ago, but the approval process has been slow.
An FDA advisory panel first voted against approving Qnexa in 2010. At issue were the heart palpitations reported, likely a side effect from the phentermine. But researchers also raised red flags about the birth defects risk that comes with Topamax. Anti-epileptic drugs (AEDs) like Topamax and Depakote (valporic acid) have long been associated with birth defects if used by women during pregnancy.
Vivus resubmitted its application for Qnexa with more information and last February an advisory panel voted to recommend the drug for approval. However, in April, the FDA dashed those hopes, saying it will take another three months to review safety data before deciding the fate of Qnexa. The new target date for approval is July 17.
If it passes this time, Qnexa will be the first diet pill in 13 years to be approved in the United States.