"New" Study Touting Weight-Loss Drug's Effectiveness Is Actually Old

The makers of weight-loss drug Qnexa say a new study shows how safe and effective it is. But critics say the study may not be that new — or that convincing.

Last year, the FDA withheld approval of Qnexa and requested more information about possible side effects, including “major cardiovascular events,” suicidal thoughts, and birth defects such as cleft palate. Now a study, published in Lancet and commissioned by Qnexa manufacturer Vivus, purports to offer new information about the drug’s safety and utility. Participants who took the drug along with lifestyle modifications lost an average of 18-22 pounds, compared to three pounds among those who just made lifestyle changes. CNN’s Matt Sloane writes that the study also found the drug (a combination of the medications phentermine and Topamax” to be “very safe,” although “at higher doses, some participants did complain about some psychiatric side effects.” According to the study summary, 7% of those taking the highest studied dose had “depression-related adverse events,” while 8% had “anxiety-related adverse events.” That’s compared to 4% and 3%, respectively, of controls, and it’s not clear whether any of these “adverse events” included suicidality. Nine study participants got pregnant while taking Qnexa, and none of their babies had cleft palates. Says a press release by Vivus, “QNEXA therapy was well tolerated, with no unexpected adverse events.”

However, Melissa Healy of the LA Times points out that the data presented in the Lancet study isn’t actually new:

This newly published article details one of two clinical trials that were evaluated by the FDA before the agency decided to deny approval for Qnexa in October 2010. When the FDA’s staff scientists combined the results of this study with a second study (both funded by Vivus, of Mountain View, Calif.) — they concluded that the weight-loss difference between those taking Qnexa and those taking a placebo was “of nominal statistical significance.”

Also, “in denying Vivus approval to market Qnexa in October, the FDA asked the company to extend the trial described in the Lancet article and to submit further findings on Qnexa’s effect on subjects’ heart function, as well as on its safety for use in women who might become pregnant.” Basically, everything in the Lancet study was information the FDA already had and found insufficiently convincing back in the fall. But the timing of its release makes it seem like it actually contains new data and addresses the FDA’s reservations.

Clearly this isn’t going to fool the FDA, but it has generated media attention, some of it pretty uncritical. Today Katie Moisse of ABC tells the story of Mary Williams: “A daily dose of Qnexa — an experimental weight loss drug that combines phentermine with topiramate, a drug approved for epilepsy and migraine prevention — along with a diet and exercise helped Williams drop 38 pounds and six dress sizes in a year.” Of the Lancet study, Moisse writes, “despite the promising results, the Food and Drug Administration rejected an application from drug maker Vivus to have Qnexa approved for the treatment of obesity, citing safety concerns.” And she quotes Vivus president Peter Tam: “I think it’s all about risk-benefit assessment. And [Qnexa] is a drug that has demonstrated a tremendous amount of benefit.” What’s getting lost here is that according to the FDA, Vivus hasn’t sufficiently evaluated the risks.

Study: Weight-Loss Combo Pill Shows Promise [CNN]
Diet Drugs: Weighing Risks, Benefits [ABC]
Diet Drug Qnexa: Don’t Get Too Carried Away By New Study [LA Times]