After first being turned down by the Food and Drug Administration, makers of the weight-loss drug Qnexa claim they have promising new data to report and have asked the FDA to reconsider it’s approval.
Vivus, Inc, of Mountain View, Calif., sought FDA approval last year to market Qnexa for weight loss in adults. But the request was denied with the FDA citing potential heart problems and birth defects in babies born to women who take the drug. Now Vivus is asking for approval of Qnexa with labeling that would exclude use by women of child-bearing age.
Qnexa combines low doses of the stimulant phentermine — long used for short-term weight loss — and the anti-seizure and migraine drug topiramate, also known as Topamax.
In March 2011, the FDA required new warnings about the risk of birth defects with Topamax and generic topiramate when the medication is used during the first trimester of pregnancy, a time when many women do not even know that they are pregnant.
The FDA urged doctors to avoid giving Topamax to pregnant women or women who are of child-bearing age and at a high risk of pregnancy, as the agency determined that alternative epilepsy and migraine medications were available that may not carry the same risk.
Last fall, an FDA panel voted against the drug’s approval, citing North American drug registry data showing that babies born to women who took topiramate had up to a 20-fold increase in cleft palates.
Vivus Inc. president Peter Tam told WebMD that subsequent investigations involving other databases suggest that the risk for the oral birth defect is actually much lower.
Based on the new information, the FDA agreed to let the company resubmit its application for limited approval for use in adults who are not likely to become pregnant.
At the request of the FDA, the company is also examining more than a decade of medical claims records involving women who took topiramate during pregnancy to treat seizures, migraines, and other conditions, Tam says.
The newly published study included 1,267 severely obese people treated at 91 sites across the country. The study examined the subjects over the course of a year.
Diabetes specialist and study co-researcher W. Timothy Garvey, MD, of the University of Alabama at Birmingham, says based on the research Qnexa appears to be the most effective weight loss drug since the Fen-Phen weight loss regimen. Among patients who completed the study, the average weight loss for patients on the higher dose of Qnexa was 14.4% of body weight, compared to 6.7% among patients on the lower dose and 2.1% among patients taking a placebo.
Vivus President, Tam says he is optimistic that Qnexa will be approved. But he acknowledges that the weight loss drug industry has had a rocky road lately.
Weight loss specialist Louis Aronne, MD, of Weill Medical College at Cornell University, says the FDA may feel pressure to approve Qnexa because it is effective, as long as the company shows that it can limit its use to those for whom it is approved.
Aronne directs the Comprehensive Weight Control Program at New York-Presbyterian Hospital.
“Obesity is a huge and growing medical problem and we need effective drugs to treat it,” he tells WebMD.
According to the company, the FDA is scheduled to make an approval decision next April. If approved, the drug could be commercially available soon after that.