Diet Drug Qnexa Gets Thumbs-Up From FDA Panel

Originally published on February 22, 2012 7:29 pm

A key federal panel Wednesday recommended the Food and Drug Administration approve the first new weight-loss drug in more than a decade.

At the conclusion of a day-long hearing, the FDA's Endocrinologic and Metabolic Drugs Advisory Committee voted 20-2 to endorse a request from Vivus to approve the drug Qnexa. The same panel gave a thumbs-down to Qnexa in 2010.

Qnexa is a combination of two generic drugs that are already on the market:

  • phentermine, a stimulant used for short periods to help control weight, and
  • topiramate, typically used for migraines and seizures.

The FDA doesn't have to follow the advice of the panel, but the agency usually does.

The FDA rejected Qnexa in 2010 because of concerns about side effects, especially possible heart problems and birth defects such as cleft lips and cleft palates. The rejection came amid a series of rejections and withdrawals of weight-loss drugs, which put a spotlight on the FDA's handling of obesity medications.

Despite the obesity epidemic, the FDA hasn't approved a new weight-loss drug since 1999. In 2011, the the diet drug Meridia was pulled from the market at the request of the FDA because of concerns about heart problems. Only one weight-loss drug, Xenical, remains on the market for long-term use, but it is only marginally effective and causes diarrhea and other unpleasant side effects.

Some advocates have urged the FDA to consider allowing some drugs to be on the market even if they have risks, given the serious health problems caused by obesity.

During Wednesday's hearing, Vivus gave a series of presentations designed to show show that the benefits of the drug outweigh the risks. The risk of birth defects, one concern, was relatively low. And obesity itself can increase the danger that women will give birth to babies with birth defects, according to one presentation.

In addition, Qnexa appears to have other health benefits beyond weight loss, such as lowering blood pressure, that could outweigh any risks posed by an increase in the heart rate seen in some patients, according to another presentation.

Vivus also outlined a plan to reduce the risk that pregnant women might take Qnexa, including regular pregnancy testing of women taking the drug.

For its part, the FDA presented concerns it had highlighted in new analyses posted on its website Friday, especially the increased risks for birth defects and the elevated heart rate. The federal Centers for Disease Control and Prevention also presented data on the birth defect risk from topiramate.

During the public comment part of the hearing, several obesity experts urged the panel to recommend approval, saying diet and exercise simply do not work for many people.

Kelly Close, who described herself as an advocate for people with obesity and diabetes, urged the panel to endorse the drug. She noted few drugs were in the pipeline for obesity. "The panel and the FDA has a chance to today to do something historic for obesity," Close said.

Joe Nadglowski of the Obesity Action Coalition, agreed. He noted that only one member of the committee had any experience with treating obesity.

"There is a significant treatment gap from Weight Watchers to bariatric surgery," Nadglowski. "There is a consequence of remaining obese."

Several health advocates, however, appealed to the panel to recommend against the drug, saying the risks outweighed the benefits.

"Qnexa doesn't give women what they need," said Kate Ryan of the National Women's Health Network, noting that many people regain whatever weight they lose while taking Qnexa once they stop taking the drug.

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A new drug to fight obesity has gotten strong support from advisers to the Food and Drug Administration. They voted today 20 to 2 in favor of Qnexa. If the FDA approves the drug, it would be the first time since 1999 that the agency has OK'd an obesity drug and Qnexa itself was originally rejected.

With me now to talk about this is NPR health correspondent Rob Stein. And, Rob, first explain how Qnexa works.

ROB STEIN, BYLINE: Sure. Qnexa is made up of two drugs that have been on the market for a while now. The first one is called phentermine, which has been used for quite a while to help people lose weight for short term use only. And the other one is called topiramate, which has been used to help people prevent migraine headaches and prevent seizures - people who have epilepsy.

And when they're combined, they seem to suppress people's appetite, so they eat less and they seem to lose significant amounts of weight.

BLOCK: And when the drug has been tested and studied, how much weight did people lose?

STEIN: Yeah. It's been pretty substantial. Between about three and 10 percent, which is really pretty good for an obesity drug. Not a lot of drugs have really reached that level and that's had significant effects on people's health related to their weight.

BLOCK: We mentioned that this drug, Qnexa, was rejected by the FDA back in 2010. Why? What happened?

STEIN: Right. There were really two big concerns. The first one was that the drug can increase heart rate and that's a big concern because heart problems have been a major concern among health - weight loss drugs in the past. You probably remember, there's been a bunch of drugs that have been on the market and then they've been pulled off the market mainly because of heart problems. Fen Phen is probably the one people recognize the most.

The second concern is about birth defects. Topiramate is known to cause birth defects, most commonly cleft lips and cleft palates, and that's a big concern, so people were really worried that if this got on the market that it wouldn't be just obese people taking it, but lots of people would be taking it and that could cause serious complications.

BLOCK: Well, given those serious complications that you just went through, what changed? Why would the panel vote today to improve it?

STEIN: Yeah. It's interesting. It's really a combination of factors. Part of it was that the company presented new data that suggested that the risk of birth defects was maybe a little bit lower than people had thought. They also presented a very detailed plan to try to prevent pregnant women or women of child bearing age from actually taking the drug to prevent birth defects from occurring.

And, also, I think it probably reflects sort of a new thinking at the FDA. There's been a lot of criticism of the FDA for not approving any new drugs in quite a while and the obesity epidemic has been raging out of control. And so there's been some thought that they really ought to sort of rethink the way they approach weight loss drugs and accept some risks for some drugs because there's some benefits from losing weight.

BLOCK: Now, Rob, I gather the vote today to recommend approval came with some conditions. What were those?

STEIN: Right, right. One condition was something I just alluded to, which was that there's going to be this strict system in place to reduce the risk that women of child bearing age will take the drug. And that will include things like it won't be available anywhere. It'll only be available at a few handpicked mail order pharmacies so that the company can sort of keep tabs on it, who's using it, how much are they using. It'll be limited to 30 day supplies and women who are taking the drug will be asked to take pregnancy tests on a regular basis.

In addition to that, they're going to ask the company that makes the drug to conduct a large study to really get a better handle on the risks of the heart because that's really the big concern from these drugs, the heart risks.

BLOCK: Now, the advisory panel is just that, it's an advisory panel. Do you expect the FDA to go along because the vote was 20 to two, to go ahead and approve the drug?

STEIN: Right. Now, the agency doesn't have to follow this advice, but traditionally, they usually do and usually when - especially when it's a lopsided vote like this, they usually do take the advice of the advisory panels.

BLOCK: OK. NPR health correspondent Rob Stein. Rob, thanks so much.

STEIN: Nice to be here. Transcript provided by NPR, Copyright NPR.