Breaking a long streak of bad news for diet drugs, an FDA advisory panel on Wednesday voted 20-2 in favor of approval for Qnexa, the combination of phentermine and topiramate under development by Vivus. Panel members strongly suggested that Vivus be required to perform a cardiovascular outcomes trial, though it was not immediately clear if this would have to be completed prior to approval.
Birth defects associated with Qnexa were another source of concern. The panel expressed strong support for a risk evaluation and mitigation strategy (REMS) to accompany any approval. But the panel ultimately was impressed by data showing a 10% weight loss at two years for people taking the drug.
“Of all the obesity drugs, this one has the highest efficacy in terms of weight loss, so that shifts the balance in terms of requiring a post-approval study rather than a pre- approval study,” panel member Sanjay Kaul told Bloomberg News.
Kaul told CardioBrief that the 20-2 vote appears more enthusiastic than the actual sentiment of the panel. Panel members remain concerned about the uncertainty regarding cardiovascular risk of the drug, including the possible adverse effects on blood pressure and heart rate. Kaul said the panel was impressed by the company's proposed REMS, but that there is little evidence demonstrating that even a strong REMS can significantly reduce adverse outcomes like birth defects.
Two other diet drugs, Contrave, the combination of naltrexone and bupropion, from Orexigen, and locaserin, from Arena, have been struggling to gain FDA approval in recent years. No new diet drug has been approved for marketing in the United States since 1999.