In the trials, patients taking naltrexone/bupropion were more likely to have an increase in blood pressure and heart rate than placebo patients, an effect that was most pronounced during the first eight weeks of treatment.
However, patients taking naltrexone/bupropion who lost at least 5 percent of their body weight achieved lower blood pressure and heart rate compared with those who lost less weight. But the most impressive improvements in blood pressure and weight loss were seen among patients taking placebo who achieved more than a 5 percent weight loss, suggesting diet and exercise is the best option for obese patients to lower their blood pressure.
Panelists were concerned that a drug that is supposed to reduce obesity -- and hopefully other comorbidities along with it -- actually raised blood pressure instead.
"This is my biggest concern," said Dr. Lamont Weide, chief of diabetes and endocrinology at Truman Medical Centers Diabetes Center in Kansas City, Mo. "That we are blunting all the good effects that we should see with weight loss."
The FDA reviewers concluded there wasn't enough data on the cardiovascular risks of the drug. The panel seemed to agree, but voted 11-8, with two panelists abstaining, that the company could submit new data after approval to show that the drug doesn't present major heart risks.
The panel's one neurologist, Dr. Michael Rogawski, said he thought the panel downplayed the drug's seizure risk.
Two patients in the clinical trials experienced seizures after going on naltrexone/bupropion; no participants in the placebo group had seizures. About one in 1,000 patients who take the drug would be expected to have a seizure, the panelists said.
"They occur only in one out of 1,000, but still, the consequences of having a seizure could be catastrophic," said Rogawski, who ended up voting in favor of the drug.
There is currently just one anti-obesity drug on the market: Orlistat (Xenical, Alli), after Abbott, the maker of another drug sibutramine (Meridia) voluntarily agreed to remove it from the U.S. market in October because of increased risk of stroke and MI.
Several physicians and other healthcare professionals contacted by MedPage Today and ABC News were pleased with the panel's decision and said that doctors badly need a new drug to help patients battle obesity.
"It is nice to have a medication that can help those who are watching their diet and boosting activity lose the weight that thus far has been a slow process," said dietitian Connie Diekman, director of University Nutrition ?at Washington University in St Louis. "This is one more option in the tool chest to deal with the obesity issue."
"Finally!" said Dr. Robert F. Kushner, professor of Medicine at Northwestern University Feinberg School of Medicine. "I fully endorse the panel's vote. The key will be to educate physicians on how to best prescribe the medication -- identify patients who will benefit from the medication and to accompany it with lifestyle and behavioral recommendations."
Paul L. Doering, a pharmacy professor at the University of Florida, said he doesn't "doubt for a minute that this drug will be wildly successful, at least at first," adding, "Time will ultimately tell if it is a good drug or not. In the meantime, I'm going to let somebody else be the first to take it."