The U.S. Food and Drug Administration (FDA) has rejected Orexigen Therapeutics Inc.'s weight-loss drug Contrave on concerns over heart safety issues. Following the announcement, shares of the California-based company plunged nearly 72 percent in Tuesday's pre-market trade to $2.52. Contrave is the third of three obesity drugs to be rejected by the US regulator since October when it turned down Arena Pharmaceuticals' lorcaserin, requesting for more data. The FDA also asked for more information about Vivus' Qnexa. In a letter to Orexigen, the FDA noted that "before your application can be approved, you must conduct a randomized, double-blind, placebo-controlled trial of sufficient size and duration to demonstrate that the risk of major adverse cardiovascular events in overweight and obese subjects treated with naltrexone/bupropion does not adversely affect the drug's benefit-risk profile."