WASHINGTON - Dieters, doctors and investors will get their first extensive look at the first of three new weight-loss drugs this week. The hope is that new drugs can succeed where many others have failed: delivering significant weight loss without risky side effects.
With the U.S. obesity rate nearing 35 percent of the adult population, expectations are high for the first new prescription drug therapies in more than a decade. Even a modestly effective drug has blockbuster potential.
None of the three medicines represents a breakthrough in research. Drug makers have made little headway in understanding and treating the causes of overeating. Two of the drugs submitted for approval simply combine existing drugs, an anti-convulsant and an amphetamine, but they have worrying side effects. The third, a new medication, is safer but less effective.
The quest for a blockbuster weight-loss drug has been plagued for decades by safety issues. The most notable was Wyeth's diet-drug combination called fen-phen, which was pulled off the market in 1997 due to links to heart-valve damage and lung problems.
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The Food and Drug Administration is expected to post its review of Vivus Inc.'s Qnexa today and will hold a public meeting Thursday to review the data. Orexigen Therapeutics Inc.'s Contrave is set for review in October, and Arena Pharmaceuticals Inc.'s lorcaserin is set for December.
"There's no obvious clear winner," said Leerink Swann analyst Steve Yoo. "If you look at different aspects, each drug shines."
To be considered effective, obesity drugs should reduce total body weight by at least 5 percent after one year, according to FDA guidelines given to companies.
Qnexa showed the best weight-loss results in clinical trials, with patients losing 13 percent to 15 percent of their body weight. But the drug had the highest rate of patient dropouts due to side effects, which include memory and concentration problems.
Qnexa is a combination of two older drugs: the amphetamine phentermine and topiramate, an anti-convulsant drug sold by Johnson & Johnson as Topamax. According to the company, phentermine helps suppress appetite, while topiramate makes patients feel more satiated.
Contrave also is a combination pill, mixing an antidepressant with an anti-convulsant drug. The drug has shown weight losses of 5 percent to 10 percent, with side effects such as nausea.
The one truly novel drug under FDA review showed the weakest results in clinical trials. Arena Pharmaceuticals' lorcaserin is a first-of-a-kind drug that acts on serotonin, a brain chemical associated with feelings of well-being and satiation. But patients in company trials lost just 5 percent of their body weight.
While Arena's drug trailed its competitors in weight loss, it appeared to have the fewest side effects, an important factor in FDA approval.
Decision Resources, a drug-industry-analysis firm, said all three drugs eventually could win approval.
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