About two years ago I wrote a blog about the latest two weight loss drugs to be rejected by the FDA. One of these drugs was Qnexa a combination pill made up of two well established medications, phentermine and topiramate (Topamax). At that time the FDA felt there was not
enough information about the potential cardiac risks of the drug to allow it to be marketed in the U.S. Now the same drug, produced by the same company, Vivus, has recently been approved by the FDA under a different name, QSymia. One of the terms of approval is that the company will conduct on-going surveillance studies to determine the cardiovascular risk of using this drug.
The FDA prescribing guidelines for QSymia are surprisingly lenient, requiring only that an otherwise healthy patient have a BMI of 30 or more. or for someone with underlying illnesses such as diabetes, a BMI of 27 or more. As an example, at 5 foot 5 inches someone with a BMI of 27 will weigh 165 lb and for the same height a BMI of 30 is 180 lb.
QSymia is comprised of two drugs with long standing FDA approval. Topiramate was approved in 1996 for treatment of epilepsy and phentermine has been on the market since 1959. Both drugs are known to suppress appetite and are associated with weight loss. In QSymia, topiramate and phenteramine are combined in a ratio of 6:1. In a 1 year study conducted by Vivus, obese subjects taking the high dose of QSymia lost on average an impressive 9% of their weight.
In 2010 I predicted it would take 10 years for drugs like QSymia to gain acceptance by the FDA. Clearly I was wrong by eight years but I wonder what happened in the past 2 years. The main concern expressed by the FDA in 2010 was potential for cardiovascular complications of using this drug combination. I have not been able to find any substantial studies providing reassurance about this potential complication. The FDA is requiring on-going surveillance studies to detect these problems but how will that work for those who take the drug now and are at potential risk? I think someone at the FDA changed their mind (or had their mind changed) rather than the about face resulting from the emergence of any convincing new information.
I believe it is wise to be skeptical of drug company sponsored studies since they tend to overstate the benefit and under report the side effects of the study drug. Talk about conflict of interest! However I was never overly convinced of the danger of these drugs to begin with in light of the long history of safe use exhibited by both up until now. Of note is the strong warning that women at risk of becoming pregnant must not receive this drug, but that warning has been in place since initial approval in 1996 of the topiramate component.
Another condition of approval for QSymia is to limit the number of pharmacies allowed to dispense the drug and for doctors to complete a simple training program before being permitted to prescribe it. I am eager to see how this works out. Painful recollections of the phen-fen debacle creates a degree of anxiety for many of my more experienced colleagues and I when thinking of prescribing a new weight loss drug. Given the limited number of available options for treating those with obesity who are at risk for complications of diabetes, hypertension, arthritis etc. it is still a tempting new opportunity.
