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Citing safety, FDA rejects another new diet drug

Manufacturer hopes to get approval in ’11

By Andrew Pollack
New York Times / October 29, 2010

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The Food and Drug Administration rejected another new diet pill yesterday, a big setback for overweight Americans amid the nation’s obesity epidemic.

The rejected drug, called Qnexa, is the third weight loss drug to suffer a significant setback this month because of concerns about safety. Last week, the FDA declined to approve another new drug, lorcaserin, because it caused tumors in rats. And earlier in the month it forced the withdrawal of Meridia from the market after 13 years, citing the risk of heart attacks and strokes for certain patients.

“It looks pretty bleak out there for anyone trying to get a drug approval for weight loss,’’ said Dr. Ken Fujioka, director of the center for weight management at the Scripps Clinic in San Diego.

Vivus, the developer of Qnexa, said late yesterday that the FDA had requested that the company provide a thorough evaluation of the drug’s potential for causing birth defects and heart problems.

The company, based in Mountain View, Calif., said it was confident it could provide this information to the FDA in about six weeks. If the FDA were to be satisfied, the drug could win approval sometime next year.

Qnexa was one of a few diet pills that represented a new generation of weight-loss drugs, with consumers and pharmaceutical companies pinning their hopes on finding the next best-selling, slimming pill after a decade-long gap in new products. Many drug companies had shied away from the diet market, after part of the popular fen-phen diet combination was removed from the market in 1997 because it damaged heart valves. The debacle resulted in huge legal settlements.

No new prescription diet pill has been approved since Roche’s Xenical in 1999. Xenical is now the only drug approved for long-term use in managing weight.

Fujioka, who is a consultant to some drug companies, including Vivus, said, “It’s tough to be a doctor and try to do something about the biggest problem in the US.’’

The FDA’s decision on Qnexa was not unexpected, given that an advisory committee to the agency had voted 10-6 against approval in July.

But it is nonetheless disappointing to some specialists because Qnexa produced about twice as much weight loss as other diet pills. In clinical trials, patients on the highest dose of Qnexa lost an average of 10.6 percent of their weight after one year, compared with 1.7 percent for those taking a placebo.

Qnexa is a combination of two existing drugs — phentermine, a stimulant that is approved for short-term use as a weight loss drug, and topiramate, an epilepsy and migraine drug sold by Johnson & Johnson under the name Topamax.

An FDA advisory committee in December will consider another diet drug, called Contrave, developed by Orexigen Therapeutics. But if that one also is not approved, some experts say it would discourage already wary pharmaceutical companies from working on drugs for obesity.

“It’s going to put the brakes on all obesity drug development for a decade,’’ said Dr. W. Timothy Garvey, chairman of the department of nutrition sciences at the University of Alabama at Birmingham, who was an investigator in the clinical trials of Qnexa.

A study published in the journal Obesity in January that used insurance records found that fewer than 1 percent of adults used obesity pills despite the considerable number of obese people. And only 11 to 18 percent of the users stayed with the drugs for longer than three months, a far greater dropout rate than for statins.

The difficulties, and safety setbacks, have already soured many pharmaceutical companies on obesity drugs. When two drugs used in the fen-phen diet pill combination were withdrawn from the market in 1997 for damaging heart valves, their manufacturer, Wyeth, now part of Pfizer, was left with more than $20 billion in liability.

Three years ago, the FDA, citing the risk of suicidal thoughts and depression, declined to approve rimonabant from Sanofi-Aventis. Other big drug companies like Merck and Pfizer then abandoned development of drugs that worked in the same way.

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