UCLA Professor Says Qnexa Has The "Highest Efficacy" for Weight Loss

2012-02-23 10:45

After a second review of its effectiveness and safety profile, Qnexa, an anti-obesity drug by Vivus Inc, has gained an FDA panel's approval and may soon become the first new prescription weight loss drug in the United States in 13 years.

“Of all the obesity drugs, this one has the highest efficacy in terms of weight loss, so that shifts the balance in terms of requiring a post-approval study rather than a pre- approval study,” said Sanjay Kaul, a cardiology professor at UCLA Cedar Sinai Medical Center and a member of the FDA’s Endocrinologic and Metabolic Drugs Advisory Committee who voted 20-2 in favor of the drug.

Qnexa combines two medications, phentermine and topiramate. Phentermine, also sold under several brand names such as Adipex, is in a class of medications known as anorectics. These drugs stimulate the hypothalamus gland (the region of the brain responsible for appetite) and affect certain neurotransmitters which ultimately suppress the appetite and lead the dieter to eat fewer calories.

Topiramate, also sold as Topamax, was originally approved as a medication that treats certain types of epileptic seizures and to prevent migraine headaches. It is also sometimes used in addiction therapy, such as the case of alcohol abuse. The drug may not only help provide a feeling of fullness and satiety, effectively reducing appetite, but may also be especially affective in those with binge-eating disorder.

In clinical trials, the drug has been found to be very effective for weight loss, however, the FDA originally voted to reject Qnexa last year because of concerns about an increased risk of heart ailments and birth defects. Side effects of phentermine include elevation of blood pressure and an increase in heart rate. The greater concern is the risk of birth defects in fetuses born to pregnant women who take topiramate.


Women who have taken topiramate during the first trimester of pregnancy have been found to have a prevalence rate of oral clefts (cleft lip) at about 0.29 percent or 5 in 1,000 live births. This is five times the overall rate of 1 in 1,000.


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