WEDNESDAY, Feb. 22 (HealthDay News) -- A U.S. Food and Drug Administration advisory panel gave its blessing Wednesday to a highly anticipated weight loss pill that had been rejected by health advisers once before.

The committee of outside physicians voted 20-2 to back the drug Qnexa, although the group urged that patients be monitored closely for potential heart problems, the Associated Press reported.

A decision by the full FDA is expected in April. The agency typically follows the recommendations of its advisory panels.

While effective at reducing weight, the drug, manufactured by Vivus Inc., was denied approval in 2010 because of its potential side effects. Before making its decision Wednesday, the advisory panel reviewed two years of data on the drug; when advisers last voted on Qnexa, only one year's worth of follow-up data was available.

The drug combines the appetite suppressant phentermine and the anti-seizure/migraine drug topiramate. Phentermine was once widely prescribed as the "phen" part of the fen-phen weight loss drug. This combo was withdrawn from the market after its use was linked to high blood pressure in the lungs and heart valve disease. The problems were related to the "fen" or fenfluramine part of the combination, not the phentermine.

No new weight loss drug has been approved in the United States in the past 13 years, according to published reports. As it stands, Xenical is the only FDA-approved drug specifically for long-term use -- up to a year -- for weight loss. Xenical is sold over-the-counter as Alli. However, other drugs may be used off-label to promote weight loss.

Last April, a study funded by Vivus found that obese patients taking Qnexa lost an average 22 pounds over a year, while also lowering their blood pressure and cholesterol levels.

Dr. Louis Aronne, founder and director of the Comprehensive Weight Control Program at New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City, was cautiously optimistic that Vivus did a good job responding to FDA safety concerns, and that the FDA will give the drug its nod of approval, with some caveats. Aronne was not involved in the trials but has been an adviser to Vivus and other companies developing weight-loss medications.

"I am not as pessimistic as most people," he said.

Vivus has reported that Qnexa may increase the risk of cleft lip in babies of women who use the drug while pregnant. Aronne said the birth defect concern could be addressed through education on who should and should not use the new drug.

"We have learned our lessons with weight loss drugs," he said. "They need to be used in the right people under the right circumstances." The heart risks need to be weighed against reductions in heart disease risk factors that come with weight loss, he said.

Qnexa is not any riskier than bariatric surgery, according to Aronne. "The problem is that it can be distributed more widely," he said. He hopes for a compromise that allows the new compound to be prescribed, but not misused. "Once new medications are approved, local medical boards will need to enforce rules and make sure these medications are prescribed appropriately to the right candidates," he said. "We don't want to open up pill mills."

One thing is clear, he said: More options to treat obesity are needed. "For hypertension, there are 120 medications in nine categories," Aronne said. "We need new options and we need to get physicians thinking about obesity and obesity treatments."

Dr. Scott Kahan, an obesity expert at Johns Hopkins University in Baltimore and director of the National Center for Weight and Wellness in Washington, D.C., agreed. He is optimistic about the FDA's upcoming decision on Qnexa. "The weight loss effects are striking and approaching the amount of weight loss over two years that we get with bariatric surgery," he said. "This is really impressive."

More information

Learn more about weight loss medications at the U.S. National Institutes of Health.