About two years ago I wrote about the two latest weight loss drugs 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 its marketing 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 of the cardiovascular risk of using this drug.
The FDA prescribing guidelines for
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 composed 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, a long acting version of topiramate and phenteramine are combined in a ratio of 6:1. In a 1 year study conducted by Vivus, obese subjects taking the Concertahigh 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 believe it is wise to be skeptical of drug company sponsored studies. Talk about conflict of interest! However the risk of these drugs is well-known in light of the long history of use by both up until now. One particularly strong warning from Vivus is that women at risk of becoming pregnant must not receive this drug. This warning has been in place since initial approval in 1996 of the topiramate component.
Another condition of approval for Qsymia by the FDA is to limit the 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 Vyvansethis works out. Painful recollections of the Fen-Phen debacle 15 years ago, creates a degree of anxiety for many experienced physicians 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.