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FDA Reconsiders Weight Loss Drug Qnexa

Weight Loss Impressive, but Safety Questions Remain

‘Most Effective Drug Since Fen-Phen’ continued...

The most commonly reported side effects were tingling, dry mouth, constipation, and a tinny taste in the mouth.

At the end of the study, average heart rate increased by one beat per minute in the higher-dose Qnexa-treated patients and by less than one beat per minute in the lower-dose patients.

Diabetes specialist and study co-researcher W. Timothy Garvey, MD, of the University of Alabama at Birmingham, says based on the research Qnexa appears to be the most effective weight loss drug since the Fen-Phen weight loss regimen. Fen-phen was a combination of two separate drugs -- fenfluramine and phentermine. Fenfluramine, which was linked to potentially fatal heart problems, was pulled from the market in the late 1990s.

Among patients who completed the study:

  • The average weight loss for patients on the higher dose of Qnexa was 14.4% of body weight, compared to 6.7% among patients on the lower dose and 2.1% among patients taking a placebo.
  • 48% of those in the higher-dose group lost 15% or more of their body weight, compared to 12% in the lower-dose group and 6% in the placebo group.

Sixteen percent of patients treated with the highest dose of the experimental combination drug dropped out of the study early because of the side effects, compared to 11% of patients in the lower-dose group and 8.4% of people who got the placebo treatments.

Tough Times for Weight Loss Drugs

Tam says he is optimistic that Qnexa will be approved. But he acknowledges that the regulatory climate for weight loss drugs has been stormy of late.

Last October, in the same month that the first Qnexa application was rejected, the FDA also rejected Arena Pharmaceuticals’ application for its weight loss drug lorcaserin for safety reasons . The agency also forced the withdrawal of the diet drug Meridia from the market after 13 years, citing concerns about heart attack and stroke risk.

Weight loss specialist Louis Aronne, MD, of Weill Medical College at Cornell University, says the FDA may feel pressure to approve Qnexa because it is effective, as long as the company shows that it can limit its use to those for whom it is approved.

Aronne directs the Comprehensive Weight Control Program at New York-Presbyterian Hospital.

"Obesity is a huge and growing medical problem and we need effective drugs to treat it," he tells WebMD.

He says just as weight loss surgery is now considered more of a medical than cosmetic procedure, a new generation of weight loss drugs will be thought of in the same way.

"This is not a cosmetic issue, it is a medical one," he says. “Weight loss has all kinds of health benefits, including improving blood pressure, diabetes, sleep apnea, and stroke and heart attack risk."

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