Diet drugs have failed to impress government health regulators in recent years with several prospective medications being denied approval and another drug taken off the market. Hopes for the first new diet pill in about 13 years now rest with a meeting Wednesday in Washington, D.C., to discuss Qnexa.
An advisory committee reporting to the Food and Drug Administration will, for the second time, hear evidence for or against the approval of Qnexa, which is a combination of two existing drugs -- the anticonvulsant topirimate and the diet drug phentermine -- that promote weight loss. The medication, made by the Mountain View, Calif.-based Vivus, first came before the FDA advisory committee in July 2010, which voted to deny approval. The FDA subsequently denied approval in October 2010, citing potential safety problems.
However, 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.
There are fewer questions about Qnexa's ability to promote weight loss. A two-year study of 4,323 people showed an average weight loss of at least 10% of total body weight and improvements in blood pressure.
Vivus officials have maintained a positive front about the drug's eventual approval. But documents filed in advance of Wednesday's meeting suggest some hard questions await Vivus officials. The FDA remains concerned with a potential increased risk of cleft palate in babies born to women who become pregnant while taking the medication. A key issue is whether Vivus can persuade the FDA that the drug will not be prescribed haphazardly to women who could become pregnant. Questions also remain regarding potential heart risks for adults taking the drug.
More is at stake than just Qnexa. The FDA has rejected applications for two other diet medications in the past two years (both of those drugs will also be resubmitted with additional follow-up data), and health professionals who work in the obesity field are growing impatient with the FDA's demands.
The Obesity Society, the Obesity Action Coalition and other medical organizations have been working with the agency for several years to discuss expanding treatment options for patients with obesity. Some obesity experts have said they feel the FDA is holding weight-loss drugs to a higher standard compared with medications that treat other conditions.
But obesity has severe health ramifications, noted James Zervios, a spokesman for the Obesity Action Coalition.
"There just aren't a lot of tools in the tool box when you're treating obesity," Zervios said. "We need other options for people."
While diet and exercise is useful for people who require only a small weight loss, and surgery is available for people with severe obesity, there are fewer options for the "in between" overweight individual, Zervios said. Qnexa targets people with a body mass index of 30 or above or a BMI of 27 or above for people who also have weight-related health problems, such as diabetes or sleep apnea. A BMI of 25 to 29 indicates overweight and 30 or greater is considered obese.
FDA officials are sympathetic to the need, Zervios said. But the potential for Qnexa to cause birth defects appears to be of great concern to the agency.
"The fear is that this drug will be used by all," he said. "Our stance is there needs to be strict guidelines in place so the right individuals are gaining access to it. It's not for people who want to lose five or 10 pounds."
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Diet drug Qnexa will get a second look
