Qnexa: Is the new anti-obesity drug too risky?

The FDA hasn't approved a new weight loss drug in 13 years. Now, an advisory panel is endorsing a previously rejected diet pill. What changed?

In a 20 to 2 ruling, an advisory panel overwhelmingly recommended the anti-obesity drug, Qnexa, for approval by the Food and Drug Administration. The FDA has not approved a weight loss drug in the past 13 years, and has removed similar diet pills from the market over concerns about heart risks and other adverse side effects. What makes Qnexa any different? Is it an important step forward in the fight against obesity, or another "quick fix" for Americans who refuse to make healthier lifestyle choices? Here's what you should know:

What is Qnexa?

It's a prescription medication for weight loss. It helps users shed pounds by suppressing appetite and speeding up metabolism. If approved by the FDA, it would be the first anti-obesity drug to be approved for medical use since 1999. When Qnexa's manufacturer, Vivus, first presented it before the agency in 2010, the FDA denied approval in a 10 to 6 vote.

Why was it rejected previously?

For weight loss drugs, side effects are a major issue. "Several potential medications for obesity and other metabolic diseases have floundered because they raise the risk of heart problems [palpitations, increased heart rate] even while causing weight loss," says Shari Roan at the Los Angeles Times. 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.)

Why is the panel recommending it this time?

With so few weight loss medications on the market and obesity at epidemic levels in America, the panel agreed that the risks posed by obesity outweighed the drug's side effects. "This is far from a great drug," Dr. David Katz of the Yale Prevention Research Center tells ABC News. "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."

Qnexa, which is made by a small California firm called Vivus Inc., and two other weight-loss drugs were rejected by the FDA in the past two years on concerns about potential safety risks. But on Wednesday, a panel of non-FDA medical experts reviewed additional clinical data that convinced panelists the drug's benefits outweigh any dangers.

The panel's 20-2 vote amounts to a recommendation that the FDA approve the drug for sale. The agency usually follows the advice of its panels but isn't required to. The FDA is expected to make a final decision by April 17.