The proposed prescription medication Qnexa from Vivus Inc. of Mountain View, Calif., helps dieters lose 10% of their weight when used in combination with diet and exercise.
The drug was rejected in a 10-6 vote the first time it came before a Food and Drug Administration (FDA) advisory panel, in 2010, due to safety concerns. However when the medication returned for another review in February, the advisory committee gave it near-unanimous approval (20-2). Because the FDA often follows the advisory panel's advice, Qnexa is likely to get FDA approval, probably by mid-April.
Qnexa is made up of two other older medications: the appetite-suppressant phentermine and the anti-seizure medication topiramate, which is sold under the brand name Topamax. The latter is used to treat epilepsy and migraines. Some physicians already prescribe the two drugs together for weight loss in what is called an off-label use, which is the practice of prescribing medications for an unapproved indication.
Supporters of Qnexa say that not only does it produce dramatic weight loss, but it helps reduce diabetes and lowers blood pressure and other cardiovascular risk factors. But critics are charging that too many safety questions remain. Research shows Qnexa caused an increased heart rate in some patients who took a high dose, and it increased the risk of cleft lip in the newborns of expectant mothers who took the drug.
Then why did the voting pattern change ask many. “We had more data to understand the benefits of the weight loss compared to the health risks in areas of greatest concern: the risk of birth defects and the effects the medicine had on cardiovascular disease,” says Abraham Thomas, chairman of the second advisory committee and a member of the first committee. Thomas is head of endocrinology at Henry Ford Hospital in Detroit. Although heart rate went up slightly in some patients, blood pressure went down, he says. There are health benefits for patients losing 5% to 10% of their weight, which many people can't do by diet and exercise alone, he says.
The committee was reassured that the FDA working with Vivus would have appropriate package labeling and a risk-reduction strategy to prevent pregnant women, or those planning to become pregnant, from taking the medication, Thomas says. The committee thought the benefits of Qnexa were “great enough” that the medication could go on the market, and then the company could do a larger clinical post-market trial to investigate whether there is more cardiovascular disease when people take the medication for several years, Thomas says.
But Sidney Wolfe, director of the health research group at Public Citizen, a consumer group, says that the risks outweigh the benefits. “We are strongly opposed to approving it. This idea that there is a magic bullet that will knock your hunger out, but not do other kinds of damage, is ridiculous.” He thinks the advisory committee approved the diet drug because members “felt there was a desperate need for a new diet drug even though many other ones had come and gone because of safety concerns.”
About two-thirds of people in this country are overweight or obese. Obesity increases the risk of heart disease, type 2 diabetes, some types of cancer and many other health problems. Qnexa is designed for people who are obese, which is roughly 30 or more pounds over a healthy weight, or those who are overweight and have other weight-related health issues such as high blood pressure, type 2 diabetes or high cholesterol.
Cardiologist Michael Lincoff, vice chairman of cardiovascular medicine at Cleveland Clinic, is helping Vivus design a post-marketing drug trial. He says the study of 11,000 people is designed to investigate cardiovascular outcomes. “We feel that a drug that reduces weight, blood pressure, triglycerides and the severity of diabetes will address the unmet needs in the treatment of cardiovascular disease.” He says the drug’s effect on heart rate “was very mild” and the heart attacks among people taking Qnexa in the drug’s earlier studies are a “tiny number and probably a result of chance.” The new study will take two to three years, he says. It’ll be expensive to do “and the reality of the marketplace is they will need an income stream to fund a trial like this.”
Vivus has declined to comment, saying it’s in a “quiet period” before the FDA makes its decision on the drug.
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