Orexigen Therapeutics said the U.S. Food and Drug Administration delayed a decision on the marketing application for its obesity drug by three months, sending the company's shares down about 19 percent in premarket trading.
The regulator indicated the extension is required to reach an agreement on the post-marketing obligations linked to the evaluation of heart risk related to the drug, contrave, Orexigen said in a statement.
The regulator, which rejected the drug in 2011, had asked the company to conduct additional trials to assess the potential for heart risk.
An interim analysis of the heart risk study showed that overweight and obese patients receiving contrave did not have a higher heart risk compared with those on a placebo, the company said in November.
Qsymia and Belviq have been slugging it out to conquer the weight-loss market, but sales have fallen far short of expectations.
Some analysts blame marketing strategies for the lower-than-expected sales of the two drugs, while others say physicians are yet to be convinced that new drugs have overcome the safety issues that caused the withdrawal of earlier diet drugs.
Qsymia and Belviq have been plagued by safety concerns, ranging from depression and anxiety to heart risks and potential harm to fetuses in pregnant patients.
Contrave is also currently being evaluated by European regulators.
Over one-third of adults in the United States are obese, according to the Centers for Disease Control and Prevention.
San Diego-based Orexigen's shares closed at $6.81 on the Nasdaq on Tuesday. (Click here for the latest quote.)