Diet Drug Qnexa Nears FDA Approval: Who Will Benefit?

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Alexander Ho for TIME

For the first time in 13 years, a new prescription weight-loss pill appears poised to hit the U.S. market.

On Wednesday, an advisory committee of the Food and Drug Administration (FDA) recommended that the agency approve Qnexa, a combination pill of two existing drugs — the anti-seizure medication topiramate and the appetite suppressant phentermine — to aid weight loss in clinically obese patients. The FDA often follows the recommendation of its advisory committees, but is not required to do so; the agency has until April 17 to make its final decision.

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.

MORE: Whither Qnexa? A Brief History of Diet Pills and the FDA

In clinical trials, Qnexa led to 10% weight loss over a year, but it was also linked with increased heart rate and birth defects when taken during pregnancy. According to the latest studies, one component of the pill, topiramate, increases the risk of oral clefts two- to five-fold when taken by pregnant women, the FDA said.

That’s why, if approved, the drug’s maker, Vivus Inc., will carefully limit its potential health risks. To reduce the risk of birth defects, women of childbearing age who use the drug will be advised to use contraception simultaneously and to get monthly pregnancy testing. Patients will also be advised to stop taking the drug after three months if it doesn’t work.

Doctors and health-care providers who prescribe the drug will be trained on the medication’s risks and benefits, and the pill will be made available only to registered pharmacies, whose pharmacists have been educated about the drug’s special prescribing circumstances and have agreed to ask doctors to abide by them.

The drug would be targeted at people with a body mass index, or BMI, of 30 or above — the clinically obese. Those with a BMI of 27 or above — considered overweight — would also be eligible if they have other weight-related health problems, such as diabetes or sleep apnea.

MORE: The Diet-Pill Dilemma

Qnexa clearly isn’t for everyone, but with more than 35% of American adults now tipping the scales into obesity, some experts believe that a new diet drug is sorely needed — as many have pointed out, there is currently no treatment that bridges the gap between diet and exercise, which doesn’t work for many, and bariatric surgery.

“There is an urgent need for better pharmacologic options for individual patients with obesity,” Elaine Morrato, an assistant professor of health systems, management and policy at the University of Colorado and a member of the FDA advisory committee, told CBS News. “I believe Qnexa demonstrated a meaningful efficacy benefit and that there are consequences to not treating obesity.”

The need appears urgent enough that the panel voted to approve Qnexa without requiring Vivus to conduct further studies on the drug’s potential heart risks before approval. Instead, the panel strongly urged the company to do the studies once Qnexa is on the market. “Of all the obesity drugs, this one has the highest efficacy in terms of weight loss, so that shifts the balance in terms of requiring a post-approval study rather than a pre-approval study,” Sanjay Kaul, a professor of cardiology at David Geffen School of Medicine at UCLA Cedars Sinai Medical Center, told Bloomberg.

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Other panel members were wary of Qnexa’s potential side effects, however, and voted against approval, arguing that more safety studies are needed first. If the agency approves the drug without such data, Dr. Michael Lauer, committee member and director of cardiovascular sciences at the National Heart, Lung and Blood Institute, told the Los Angeles Times, “it would be a decision based on hopes, surrogates and suppositions.”

Whether or not Lauer is right, the decision now lies with the FDA. If the agency follows the panel’s advice, it would be welcome news for legions of obese Americans who have few other options. Currently, the only one other diet drug available by prescription is Xenical, which works by preventing the body from absorbing fat from food (it is also available over the counter in lower doses under the brand name Alli), but is rarely used.

Qnexa could fill a crucial need. As Joe Nadglowski, president and CEO of Obesity Action Coalition, a patient advocacy group, told WebMD: there is “a significant treatment gap from Weight Watchers to [bariatric] surgery.”

Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.