FDA to review 1st of 3 obesity drugs

July 12, 2010 at 12:00a.m.

Associated Press

WASHINGTON

Dieters, doctors and investors get their first extensive look at the first of a trio of new weight-loss drugs this week. The hope is that the new drugs can succeed where many others have failed: delivering significant weight loss without risky side effects.

With U.S. obesity rates nearing 35 percent of the adult population, expectations are high for the first new prescription-drug therapies to emerge in more than a decade. Even a modestly effective drug has blockbuster potential.

None of the three medicines represents a breakthrough in research. Two of the drugs submitted for approval simply combine existing drugs — an anticonvulsant and an amphetamine — but 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 pill drug combination fen-phen, which was pulled off the market in 1997 due to links to heart-valve damage and lung problems.

The FDA is expected to post its review of Vivus Inc.’s pill Qnexa today. Orexigen Therapeutics Inc.’s Contrave is set for review in October, and Arena Pharmaceuticals Inc.’s lorcaserin is in December.

To be considered effective, obesity drugs should reduce total body weight by at least 5 percent after one year, according to FDA guidance to companies.

Qnexa showed the best weight-loss results in clinical trials, with losses between 13 percent and 15 percent of patients’ body weight. But the drug also had the highest rate of dropouts from side effects, which include memory and concentration problems.

Qnexa is a combination of two older drugs: the amphetamine phentermine and topiramate, an anticonvulsant drug sold as Topamax.

Contrave also is a combination pill, mixing an antidepressant with an anticonvulsant drug. The drug has shown weight loss between 5 percent and 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.