Miracle diet pill? A safe drug is elusive

Obesity, a leading cause of diabetes, heart disease and other serious health problems, has reached epidemic proportions in the United States, with about a third of the population obese and more than half overweight. The FDA has set a high approval bar for weight loss drugs because such a large portion of the general population is likely to want to take them, and has not approved a new obesity drug since 1999.  The drug would only be available from 10 mail-order pharmacies. Qnexa’s other ingredient, Phentermine, was one half of the dangerous fen-phen combination, a weight loss treatment pushed by doctors that was never approved by the FDA. The regimen was linked to heart-valve damage and lung problems in the late 1990s, and the FDA forced drugmaker Wyeth to withdraw two versions of its drug fenfluramine. 

“The FDA panel recommended approval of Qnexa only because the ranks of useful weight loss drugs are so thin, and desperate times call for desperate measures.  At a public meeting Wednesday, an FDA panel of outside physicians voted 20-2 in favor of the weight loss drug from Vivus, setting the stage for a potential comeback for a drug that has been Plagued by safety questions since it was first submitted to the agency in 2010. Nearly all the panelists backed the drug due to its impressive weight loss results, with most patients losing nearly 10 percent of their overall weight after a year on the drug.

At the time the FDA said the drug resulted in “significant” weight loss but the agency said it was concerned about a possible risk of birth defects and an unknown impact on the heart. FDA officials left the door open for Qnexa, asking Vivus to provide additional data on whether the medication can cause birth defects and what the risk of birth defects might be. The agency has also requested data on whether the slight increase in heart rate that is linked to the drug increases the risk of cardiovascular events, such as heart attack and stroke. The FDA has expressed concern that the drug might impair memory, trigger suicidal thoughts, raise heart rates and cause birth defects, warning that babies whose mothers take the Qnexa ingredient topiramate “have an increased risk for developing cleft lip or cleft palate” during pregnancy.

The FDA has said the rate of potential birth defects is about two to five times higher with topiramate than with a placebo. Vivus officials said obesity, and its common symptom diabetes, come with their own risks to pregnancy, such as stillbirth, premature birth and other complications. Arena and Orexigen have been pitching their own fat-fighters to the FDA after rejections. In February, Orexigen agreed with the FDA on the design of a 10,000-patient heart-safety trial required for the approval of its Contrave drug.

The panel’s 20-to-2 vote in favor of approval was a decisive reversal of a previous panel’s decision in 2010, when Qnexa was rejected over concerns of increased heart rate and birth defects. That panel concluded that the drug’s weight-loss benefits did not outweigh its potential risks.  The drug is linked to a small risk of birth defects and an increase in heart rate. In a public comment period, those opposed to the drug’s approval said they feared the potential for birth defects because many of the people interested in taking the drug will likely be women of childbearing age. “Diet drug history is littered with those banned only after they found about cardiovascular risk areas,” Wolfe told the committee.  Part of it was that the company presented new data that suggested that the risk of birth defects was maybe a little bit lower than people had thought. They also presented a very detailed plan to try to prevent pregnant women or women of child bearing age from actually taking the drug to prevent birth defects from occurring.

An FDA expert on birth defects estimated there would be five babies born with a cleft lip defect for every 1,000 women who became pregnant while taking Qnexa. If approved, FDA scientists said they would require Vivus to train prescribers to educate patients on the pregnancy risks of Qnexa.  Qnexa posed many of the same risks for patients, but was also found to be linked to birth defects. (“An FDA expert on birth defects estimated there would be five babies born with a cleft lip defect for every 1,000 women who became pregnant while taking Qnexa,” says the Associated Press.)

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