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Qnexa Approval Paves Way for another Obesity Drug

An FDA advisory committee’s endorsement of the anti-obesity drug Qnexa could re-energize the pharmaceutical industry after several years of disappointment in trying to develop anti-obesity drugs.

The committee voted 20 to 2 to recommend approval of Qnexa, which is a combination of two existing drugs, the appetite suppressant phenteramine and the anti-seizure medication topiramate. The FDA will issue its decision by April 17.

If approved this time around, Qnexa would be the first new prescription weight-loss medication since 1999. Only one other medication, Orlistat, is on the market. Several other obesity medications have failed to pass muster with the FDA and the drug Meridia, was taken off the market in 2010 following studies that found an increased risk of serious heart problems.

Several anti-obesity drugs remain in the pipeline, however. How they fare before the FDA may hinge on a meeting next month in which agency officials and pharmaceutical industry experts will discuss how to assess obesity drugs for cardiovascular safety. Several potential medications for obesity and other metabolic diseases have floundered because they raise the risk of heart problems even while causing weight loss.

Regulators must decide how much proof is necessary that a new drug won’t cause heart attacks, strokes or deaths. Qnexa will likely be approved with a requirement to conduct a post-marketing study to assess cardiovascular risks. However, the makers of another drug in the pipeline, Contrave, is set to begin a 10,000-person clinical trial to demonstrate the medication does not cause major cardiovascular events, like heart attacks and stroke. An FDA advisory committee voted in 2010 to approve Contrave, but the FDA turned down the application and asked for more study because the drug increased blood pressure. Arena announced it would begin the study in the second quarter of 2012.

Contrave, like Qnexa, is a combination of medications — buproprion, which is currently used for tobacco cessation and naltrexone, which is used to relieve some of the cravings involved in recovery from alcohol and opioid dependence. It works by suppressing appetite and speeding up metabolism.

An advisory committee also voted against another anti-obesity medication, Arena Pharmaceutical’s lorcaserin (or Lorqess) in 2010. That medication, also an appetite suppressive, is linked to an increased risk of heart-valve problems but also failed to impress the advisory committee with its clinical-trial data showing only a modest weight loss. Arena, too, has not given up. Officials have been working with FDA on how best to resolve outstanding questions regarding safety and effectiveness.

Doctors who treat obesity complain that FDA hurdles have soured the pharmaceutical industry on developing anti-obesity drugs. The industry has had to weigh its troubled history with obesity drugs against the fact that two-thirds of American adults are overweight or obese and a good medication will likely become a blockbuster.

Ted Kyle, chairman of the Obesity Society’s advocacy committee, who attended the Qnexa hearing stated that, “The fact that FDA and their advisers are taking obesity more seriously, as reflected in their comments during the hearing, does encourage me that these other treatments will get a more balanced hearing than they did last time.” “I only hope that they will not regard this one imperfect tool as enough for now. We need all the tools we can get because the toolbox is pretty bare.”

And indeed, the market for drugs that have a palpable effect on obesity without severe health risks is wanting — few options exist outside bariatric surgery (a step many feel is drastic and unnecessary) and standard dieting, with the latter option clearly not having that much of an impact on America’s obesity epidemic. Part of the reason obesity is such a persistent problem among Americans too is that the issue is caused by a multitude of factors and thus difficult to tackle with a single therapy such as drugs.

Dr. Mitchell Roslin is chief of bariatric surgery at Northern Westchester Hospital in New York, and he explains: “Having a drug for obesity would be like telling me you had a drug for the fever. There can be millions of different reasons why someone is obese; it’s really a symptom of various underlying mechanisms.”

Vivus. VI-0521 (QNEXA) advisory committee briefing document. February 22, 2012.