Clamor for obesity pill may test FDA limits
Analysts predict that Qnexa, if approved, will be prescribed widely, with annual sales of $1 billion to $3 billion.
It combines the appetite suppressant phentermine with the anti-seizure drug topiramate, and helped patients lose 10 percent of their weight after a year during trials. However, the pounds started to creep back on after the first 12 months.
In terms of weight loss, Qnexa will likely produce smiles. Clinical data (not yet published) showed participants lost an average of 10 percent of their body weight, according to Vivus’ claims. But as Robert Carlisle’s Mr. Gold loves to say on the TV hit Once Upon a Time, “All magic comes at a price.” What’s the price to your overall health of taking Qnexa?
Let’s start with what’s in the drug. Qnexa is actually a “cocktail,” meaning it’s a combination of two previously FDA-approved drugs, phentermine - an appetite suppressant - and topiramate, an anti-convulsant.
FDA staff reviewers said patients taking the drug had more safety problems, including memory loss and higher heart rates, than those on a placebo. They also said exposure to topiramate has been linked to a higher rate of oral clefts in infants of women taking the drug during pregnancy.
Experts worry subtle messages of risk versus benefit may slip past people desperate to shed pounds, and there is little the FDA can do to stop them.
“Perhaps the only thing that would be better than a pill to help you lose weight would be a pill that makes you more beautiful,” said Dr. David Gortler, a former FDA medical officer on the obesity team and current professor of pharmacology at Georgetown Medical School. “In fact, many fashion advertisers promote and equate beauty with the loss of weight.
“There is going to be a huge demand for Qnexa... (and) if the FDA doesn’t regulate Qnexa appropriately there are going to be a deluge of lawsuits,” said Gortler.
SLIPPING THROUGH THE CRACKS
The FDA often proposes risk mitigation programs to deal with drugs that may cause birth defects. One of the most restrictive is for the acne drug Accutane from Roche, which is known to cause severe birth defects.
Women who want the drug must take tests every month to prove they are not pregnant. But there is a lack of good information about how effective these programs are.
The FDA rejected the diet pill Qnexa in October 2010, citing numerous side effects including raised heart rate, psychiatric problems and birth defects. Vivus has resubmitted the drug with additional follow-up information on safety, hoping for a more favorable ruling.
Vivus President Peter Tam said the overwhelming panel vote Wednesday underscores the need for effective weight loss drugs.
“I think they see the medical need,” Tam said. “Right now there aren’t any good treatments out there besides dieting and bariatric surgery, clearly there’s a huge gap.”
Dr. John Jenkins, head of the FDA’s office of new drugs, said such programs are pretty good at avoiding women who are pregnant at the time of first receiving the drug.
“They are not as good at preventing women from receiving it who are pregnant while they are already on the drug,” Jenkins told the panel last week. “While we think the number of pregnancies is less, we don’t have definitive data.”
Qnexa has some uncertain effects on the heart: it lowers blood pressure, but raises heartbeat. Doctors on the FDA panel were divided about what signal that sends, and asked Vivus to conduct more studies on heart safety, most likely after Qnexa is approved.
“This drug, if approved, would likely be prescribed to millions or tens of millions of people,” said Dr. Michael Lauer, director of the division of cardiovascular sciences at the National Institutes of Health.
Lauer was one of two people who voted against Qnexa‘s approval at the FDA panel last week. “Based on the data that we’ve seen, we think this drug may do enormous good,” he said during the panel meeting. “But we may not know that for a long time, or we may find out we’ve been fooled.”