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Weight Loss Drug Contrave Gets Thumbs Down From FDA

The Food and Drug Administration rejected the weight loss drug Contrave yesterday (Jan. 31), and asked for more evidence showing the drug does not pose risks to cardiovascular health, according to the pill's manufacturer.

The FDA issued a response letter to Orexigen Therapeutics Inc., expressing concern over the drug's potential hazards, the company said in a statement. In previous trials, Contrave has been shown to elevate blood pressure and pulse rate side effects that could increase the risk of heart attack and stroke , said Dr. Pieter Cohen, an assistant professor of medicine at Harvard Medical School.

The drug will not be approved until the company conducts a clinical trial and shows that Contrave does not pose cardiovascular risks to obese and overweight individuals that would outweigh the benefits gained from weight loss, the company's statement said.

The FDA's decision goes against recommendations made in December by an FDA panel appointed to review the drug's safety and efficacy. The panel voted to recommend Contrave be approved, but also urged additional safety trials following approval.

"I think the FDA did the right thing," in requesting further research before approving Contrave, Cohen said. "This will allow us to sort out whether or not Contrave will offer more benefit or harm to the people who are overweight before allowing it to be marketed in the U.S."

Because two-thirds of Americans are overweight or obese , the drug could potentially be sold to millions of people, Cohen said. "It's extremely important that a drug for weight loss, which will be used widely, should be safe."

Future trials of Contrave should study all adverse effects, Cohen said. Contrave is made of up two drugs, bupropion and naltrexone. Bupropion has been linked to seizures, Cohen said.

The FDA has rejected a string of diet pills recently. They include lorcaserin, manufactured by Arena Pharmaceuticals Inc., and Qnexa, made by Vivus Inc., both denied approval in October 2010. Also during that month, the FDA requested that Abbott Laboratories remove its weight loss drug Meridia from the market after a study linked the drug with an increased risk of heart attack and stroke.

The San Diego, Calif.-based Orexigen requested that Contrave be approved to treat those with a body mass index (BMI) of 30 or above, and those with a BMI of 27 and above, that have conditions such as diabetes and hypertension.

To be approved, the FDA requires weight loss drugs meet one of two requirements: Those taking the drug must lose 5 percent more of their body weight than those taking a placebo, or the number of treated patients who lose 5 percent of their body weight must be double the number of placebo-treated patients who lose 5 percent of their body weight.

In clinical trials, Contrave caused people to lose, on average, a little more than 4 percent more of their body weight compared with those taking the placebo, Cohen said. However, the drug did meet the FDA's second requirement.

With its response yesterday, "what the FDA is signaling to companies is that, in order to market something broadly to the American people, you need to have a truly effective treatment. Not only does it need to be truly effective and meet significant weight loss, but be safe," Cohen said.

Pass it on: The FDA denied approving the weight loss drug Contrave. Its manufacturer will have to conduct further trials to examine the drug's potential cardiovascular risks.

Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @Rachael_MHND.

Rachael has been with Live Science since 2010. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.