With one-third of Americans suffering from obesity, and another one-third being overweight, a Food and Drug Administration panel's recommendation that Qnexa be the first new obesity drug to be approved in 13 years would seem to be a no-brainer.
By Matt Mendelsohn, USA TODAY
Fenfluramine, which was part of the weight loss drug known as fen-phen, and dexfenfluramine were removed from the market in 1997.
By Matt Mendelsohn, USA TODAY
Fenfluramine, which was part of the weight loss drug known as fen-phen, and dexfenfluramine were removed from the market in 1997.
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Not so fast. Though studies have shown that Qnexa can lead to a dramatic loss of 10% of body weight in a year, concern over potential side effects kept a similar FDA panel from approving the drug as recently as 2010.
Qnexa combines two drugs associated with weight loss: the appetite-suppressant phentermine and the anti-seizure drug topiramate, which appears to alter hunger hormones, decrease appetite, and adjust glucose and insulin concentrations.
Though you might be familiar with phentermine from its presence in the infamous weight-loss drug "fen-phen," phentermine is not the main problem in Qnexa. Fen-Phen was removed from the market in 1997 amid lawsuits for heart valve problems and high pressures in the lungs. But these side effects were caused by the fen (fenfluramine), not the phen.
Phentermine is an effective weight-loss drug that suppresses appetite. Though it can increase heart rate and blood pressure, and cause palpitations, for many patients it is very well tolerated. The concerns with Qnexa center on its other main ingredient, topiramate. Those concerns caused the FDA to reject Qnexa less than two years ago.
Problems can't be ignored
So what has changed the momentum from FDA rejection to possible approval? It surely wasn't a study, completed late last year, which showed that topiramate doubles the risk of cleft lip and palate in newborns of mothers who were taking the drug. The new FDA panel virtually ignored the results of this study, accepting the reassurances of Qnexa's manufacturer, Vivus, that it will restrict the drug for pregnant women and perform studies after approval to assess heart safety.
Vivus also argued effectively to the panel that the growing obesity epidemic is causing massive medical problems, and increasing the need for effective treatments. Although I agree that the growing weight problem in the U.S. leads to millions of cases of high-blood pressure, diabetes, strokes and premature deaths each year, the FDA shouldn't be pressured into prematurely approving Qnexa without first being absolutely certain about its safety.
Downsides to ingredient
In addition to fighting seizures, topiramate is commonly used to prevent debilitating migraines. As someone who prescribes it regularly, I know it can cause cognitive slowing, problems with memory and decision-making, and fatigue in addition to the risk of birth defects.
Some of the risks might be worth taking for a patient with intractable migraines or seizures, but what about obesity?
Certainly, we need new drugs to treat obesity in patients who are unable to modify their diet or lifestyle enough to lose significant amounts of weight. Perhaps Qnexa might one day be that drug. I would like to see more studies done on Qnexa, however, because its two components (topiramate and phentermine) haven't been used in combination before, and we need to assess their combined side effects.
For the sake of my obese patients who have run out of options, my vote could one day be "yes" for a drug such as Qnexa. But that day isn't here yet. Right now, the most rational vote is for more studies.
Marc Siegel, MD, is a professor of medicine and medical director of Doctor Radio at NYU Langone Medical Center. He is a member of USA TODAY's Board of Contributors and author of The Inner Pulse.
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Original post:
Column: Safety of new obesity drug requires more FDA study
