Some progress, but still slim pickings for diet drugs

For the first time in over a decade, the FDA has approved a new weight-loss drug: Arena Pharmaceuticals' Belviq (lorcaserin). The drug, which works by stimulating specific serotonin receptors in the brain to create a sense of satiety, is approved for use in obese people and those with a body mass index (BMI) of 27 or higher although those in the latter group must also have at least one weight-related health condition. In clinical trials, approximately half the patients taking Belviq lost about 5 percent of their body weight over the course of a year a modest amount. A smaller fraction lost substantially more, however.

Back in 2010, the FDA denied the drug s approval, citing evidence that it was associated with tumors in rats, as well as their concern that the drug might have cardiovascular risks. Thus the company conducted more clinical trials and submitted new data this year, alleviating the agency 's concerns. However, Arena will still be required to conduct additional studies to monitor the drug's safety, including one designed specifically to examine its cardiovascular effects.

For a country with two-thirds of its adult population overweight or obese, the approval of lorcaserin is good news, say most health experts. Perhaps the loudest dissenting voice, however, is that of Dr. Sidney Wolfe, who wrote to the FDA on behalf of his group, Public Citizen's Health Research arm. Wolfe claimed in his letter that the risk of heart valve damage should preclude FDA approval of the drug. But Wolfe's cries are purely hypothetical, says ACSH's Dr. Josh Bloom. Dr. Wolfe clearly needs a chemistry lesson. The heart valve problems that were caused by the now-banned diet drug fen-phen to which he is clearly alluding were traced to a single metabolite of fenfluramine, the fen component. It is absolutely impossible to form this same metabolite from lorcaserin, due to the difference in its chemical structure.