A New Weight Loss Drug?
Volunteers who took Qnexa, a combination of the drugs phentermine and topiramate, experienced substantial weight loss, even if they had many weight-related health problems, the study found. The findings were reported this week during the European Congress on Obesity in Lyon, France.
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The 56-week clinical trial included 994 patients who took a placebo, 498 who took a medium dose of Qnexa, and 995 who took a high dose of the drug.
Patients who took Qnexa had significantly greater weight loss than those who took the placebo, researchers Stephan Rossner, of the Karolinska Institute in Stockholm, Sweden, and Arya Sharma, of the University of Alberta in Edmonton, Canada, said in a news release from the European Congress on Obesity.
Earlier this year, a U.S. Food and Drug Administration advisory panel recommended that the agency approve the drug for the treatment of obesity. The FDA is scheduled to announce its decision July 17. European officials are expected to make a decision about the combination treatment by mid-summer.
Meanwhile, an FDA advisory panel on Thursday gave its blessing to yet another new weight-loss drug, locaserin, despite lingering concerns about possible cardiac side effects, the Associated Press reported.
Although effective at reducing weight, Qnexa, manufactured by Vivus Inc., was denied approval in 2010 because of its potential side effects. Before making its decision in February, the FDA advisory panel reviewed two years of data on the drug; when advisers previously voted on Qnexa, only one year’s worth of follow-up data was available.
Qnexa combines the appetite suppressant phentermine (brand name Adipex-P) and the anti-seizure/migraine medication topiramate (brand name Topamax). Phentermine once was prescribed widely as the “phen” part of the fen-phen weight-loss drug, which was withdrawn from the market in 1997 after its use was linked to both high blood pressure in the lungs and heart valve disease. The problems were related to the “fen,” or fenfluramine, part of the combination, not the phentermine, scientists said.
No new weight-loss drug has been approved in the United States in the past 13 years, according to published reports. As it stands, Xenical is the only FDA-approved drug specifically for long-term use — up to a year — for weight loss. Xenical is sold over the counter as Alli. Other drugs, however, may be used off-label to promote weight loss.
Last April, a study funded by Vivus found that obese patients taking Qnexa lost an average of 22 pounds over a year, while also lowering their blood pressure and cholesterol levels.
Dr. Louis Aronne, founder and director of the Comprehensive Weight Control Program at New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City, was cautiously optimistic that Vivus did a good job responding to FDA safety concerns, and that the FDA will give the drug its nod of approval — with some caveats. Aronne was not involved in the trials but has been an adviser to Vivus and other companies developing weight-loss medications.
Vivus has reported that Qnexa may increase the risk of cleft lip in babies of women who use the drug while pregnant. Aronne said the birth defect concern could be addressed through education on who should and should not use the drug.
“We have learned our lessons with weight-loss drugs,” he said. “They need to be used in the right people under the right circumstances.” The heart risks need to be weighed against reductions in heart disease risk factors that come with weight loss, he explained.
Qnexa is no riskier than bariatric surgery, Aronne said, but it can be distributed more widely. He hopes for a compromise that allows the new compound to be prescribed but not misused.
“Once new medications are approved, local medical boards will need to enforce rules and make sure these medications are prescribed appropriately to the right candidates,” he said. “We don’t want to open up pill mills.”
Dr. Scott Kahan, an obesity expert at Johns Hopkins University in Baltimore and director of the National Center for Weight and Wellness in Washington, D.C., agreed that Qnexa looks promising.
“The weight-loss effects are striking and approaching the amount of weight loss over two years that we get with bariatric surgery,” Kahan said. “This is really impressive.”