Wednesday, February 2, 2011

FDA Rejects Contrave for Obesity--Big Mistake

As you can read from various sources, including the NY Times, the LA Times, and the Washington Post, the FDA has rejected another anti-obesity drug, Contrave, because of concerns that it might cause heart attacks in patients who take it for years.

FDA's excessive caution was motivated by its experience having been burned by the Fen-Phen fiasco. This was a weight loss drug widely prescribed in the 90s that was pulled from the market after studies showed it caused fatal lung and heart valve problems. 

This new drug, however, is a combination of two medications that have already been widely prescribed and are fairly safe: Wellbutrin and naltrexone. Psychiatrists are familiar with both of them. We prescribe Wellbutrin for depression and smoking cessation, (and off-label for weight loss, for which it has shown efficacy as a stand alone), and we prescribe naltrexone for alcoholism.

As you can see from information published on, Contrave is simply a combination of Wellbutrin 400 mg with Naltrexone at a couple of different doses, 48 mg and 16 mg. Clinical trials showed that Contrave helped 50% of obese patients lose 5% of their body weight, while only 10% of patients on placebo lost that much weight. The FDA's advisory panel voted to recommend approval, but the FDA demurred, saying that the company, Orexigen, will have to conduct a huge placebo-controlled long term study to make sure the drug doesn't cause heart attacks (one of Wellbutrin's well-known side effects is a slight increase in pulse and blood pressure, although there were no heart attacks in the Contrave clincial trials).

In my opinion, the FDA made the wrong decision. Obesity is a public health catastrophe, and Contrave's approval would have been predicated on conducting post-marketing safety studies anyway. The good news is that patients can ask doctors to prescribe them the constituents of Contrave, both of which are available in generic form--burpropion and naltrexone. Presumably, this generic combination will be much cheaper than Contrave's pricing anyway!