Dr. Walt's Health Blog

FDA panel recommends new weight-loss drug

A panel of experts for the Food and Drug Administration (FDA) recommended a new diet drug called phentermine/topiramate [Qnexa] be approved. The recommendation comes despite concerns about heart and birth defect risks.

According to NBC News, the reviewers “said the drug’s effectiveness outweighs any potential risks.” While ABC World News quoted Dr. Tim Garey, of the University of Alabama, who said, “If approved, Qnexa would be the most potent medicine we would have on the market to treat obesity. Currently available drugs are not very effective.”

ABC’s Dr. Richard Besser said the drug was “rejected two years ago by the FDA for safety concerns, today’s panel said for obese people, the benefits of Qnexa outweigh the risks.”

But “opponents aren’t shy about their skepticism.” Dr. Sidney Wolfe, with Public Citizen, said, “I think diet drugs really fall in the category of if it’s too good to be true.”

CBS Evening News reported that the drug “failed to win advisory committee approval in 2010 because one ingredient, phentermine, an ingredient in the failed diet drug fen-fen, was linked to heart problems. The other, topiramate, was linked to birth defects,” Dr. Jon LaPook said.

He added, “The drug maker has agreed to continue to monitor patients for potential heart problems and to warn women taking the drug not to get pregnant.”

The New York Times reports the FDA’s “advisory panel overwhelmingly recommended approval of what could become the first new prescription drug to treat obesity in 13 years.”

The panel “voted 20 to 2 that the benefits from the weight loss provided by the drug, Qnexa, more than offset the potential risks of heart problems and birth defects.”

The Times added, “The strongly positive vote, which was not widely expected, represents a stunning comeback for Qnexa and for its developer, the drug company Vivus.”

“In a clinical trial involving 4,323 people, Qnexa – a combination of the anticonvulsant drug topiramate and the appetite suppressant phentermine – led to an average loss of about 10% of total body weight in the first year of use,” the Los Angeles Times reports.

“But the trials also found that that the drug caused a slight increase in heart rate, which can boost the odds of a heart attack or stroke.”

Additionally, “researchers detected an increased risk of birth defects – typically cleft lip – in women who became pregnant while taking the drug.”

The AP added, “A majority of panelists ultimately backed the drug due to its impressive weight loss results, with most patients reporting nearly 10 percent weight loss.”

Still, “the group stressed the importance of confirming the drug’s safety, particularly its effects the heart, by tracking patients in a large, follow-up study.”

The agency’s “decision is expected in April.”

Bloomberg News reports, “The FDA plans to have advisers discuss in March the possibility of requiring heart-risk studies for all weight-loss drugs.”

In addition, “panel members discussed whether Vivus should conduct such a study before or after approval.”

The company “has proposed a post-approval trial to assess Qnexa in reducing major heart complications in obese, at-risk patients,” which “would involve 11,300 patients and take four and a-half years.”

“In clinical trial data submitted to the FDA by manufacturer Vivus, patients who took higher and lower dose versions of the drug for two years lost between 3 to 10 percent of their weight on average, compared with a 2 percent loss in those who took placebos,” the Boston Globe reports.

“The amount of weight lost by patients taking Qnexa led to an improvement in obesity-related health conditions, such as a reduction in high blood pressure and the diabetes marker hemoglobin A1C, and a boost in ‘good’ HDL cholesterol levels.”

However, patients “on low-dose and high-dose versions of Qnexa, as well as the placebo group, began to regain lost weight after the first year of the study, so it’s not known how long the effects of the drug will last for those who take it for several years.”

MedPage Today reported, “To address the concerns over side effects, Vivus worked with the FDA to develop a risk mitigation strategy for Qnexa,” which included “labeling stating that the drug is in Pregnancy Category X (contraindicated in women who may become pregnant) and that the drug should be discontinued if the patient becomes pregnant.”

In addition, the drug will be distributed “only through 10 certified mail-order pharmacies that agree to training of their pharmacists in use of the drug and submitting to internal audits.”

The company will also create “education programs aimed at providers and patients” and it will develop “a pregnancy registry to track pregnancy outcomes.”

2 Responses to “FDA panel recommends new weight-loss drug”

  1. Craig DeLisi writes:

    As a family physician, I’m always skeptical of medications that are given to treat obesity. My experience is that while initial weight loss can be attained via these drugs, sustainable weight loss rarely is. I think the reason for this is that most of the medications decrease appetite and increase metabolism. This negates the need to make healthy, permanent changes in lifestyle. Almost without exception, patients that I’ve encountered on phentermine gain back ALL of the weight they loss. I would expect nothing different with Qnexa.

  2. Dr. Walt writes:

    Craig,

    Qnexa may play a role in some patients … especially those willing to, along with the medication, see a dietician and begin a supervised exercise program. This new medication combines phentermine plus controlled-release topiramate. And, the data, to date, show that the combo is more effective than either drug alone for weight loss.

    How well does it work? Qnexa helps patients lose about 10% of their body weight … or an average of 24 pounds in one year. This compares to about 5 to 10 pounds with phentermine, diethylpropion, or orlistat…and 13 pounds with topiramate.

    Some prescribers, myself included, are already prescribing phentermine in the morning plus topiramate (Topamax, etc) in the evening for weight loss. The advantage of the new med is that the topiramate portion is extended relief which may reduce side effects. The potential disadvantage is that I suspect it will be very expensive. However, should it help patients lose weight and keep it off (as you point out, a BIG IF), then it may be worth the cost.

    Of course, all of us who chose to prescribe Qnexa, should it be approved, must caution patients about possible side effects with these drugs. Phentermine can increase heart rate and blood pressure like other stimulants…but it doesn’t cause heart valve problems like fenfluramine. And, topiramate is sometimes called “Dopamax” … because it can cause fatigue, slowed thinking, and impaired memory and concentration. Also, we have to be careful not to give topiramate to women during pregnancy … due to an increased risk of birth defects.

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