But a long line of prescription weight loss offerings have been associated with safety problems, most notably the fen-phen combination, which was linked to heart valve damage in 1997. The cocktail of phentermine and fenfluramine was a popular weight loss combination prescribed by doctors, though it was never approved by FDA. In a rare move, the FDA explicitly stated in a press release that Belviq “does not appear to activate” a chemical pathway that was linked to the heart problems seen with fen-phen.
The FDA says the drug acts on a different chemical pathway in the brain, which is believed to reduce appetite by boosting feelings of satiety and fullness.
Belviq is one of three experimental weight-loss drugs whose developers have been trying for a second time to win approval, after the FDA shot them all down in 2010 or early 2011 because of serious potential side effects.
Vivus Inc.’s Qnexa is thought to be the most promising of the drugs, achieving the most weight loss. But the FDA has delayed a decision on that pill until July.