WASHINGTON — An advisory panel to the Food and Drug Administration set aside lingering concerns about the safety and marginal effectiveness of the latest weight-loss drug to come before it, voting 13-7 on Tuesday to recommend the approval of Contrave, a combination of two medications available since the mid-1980s — the antidepressant and smoking-cessation drug bupropion and the anti-addiction medication naltrexone.
Tuesday's vote made Contrave the first of three weight-loss drugs reviewed by the FDA panel in 2010 to win favor.
But the panel, which is made up of outside experts, strongly encouraged the FDA to require further testing of the medication, especially on safety, from its first days on the market.
In a separate vote taken earlier, eight of the committee's 20 members had recommended a delay in the FDA's approval of the drug until a lengthy trial addressing safety was completed. But they were outvoted by 11 who said that such testing could be done by tracking 10 percent of the millions of patients likely to take the drug after it is approved and in general use.
The FDA is to rule on whether to approve Contrave as a weight-loss drug for potential long-term use early in the new year. Although the agency is not obliged to follow the advisory panel's recommendations, it usually does.
In four clinical trials presented to the panel at Tuesday's meeting outside Washington, D.C., Contrave was found to have helped obese subjects to lose more weight than a dummy pill. But advisory panel members said the results gleaned from about 4,500 subjects who took the pill, often with weight-loss counseling as well, were far less impressive than had been hoped.
An FDA staff report said weight-loss differences between those taking Contrave and those taking a placebo for a year were, overall, "of nominal statistical significance" and failed to meet one criterion set by the agency for diet prescription medications: that subjects taking a diet drug in clinical trials lose at least 5 percent more than those taking a placebo.
Contrave did, however, satisfy the second criterion: More than half of subjects taking the medication in each of the four trials lost at least 5 percent of their body weight.
"In terms of efficacy, they made it by the hair of their chinny-chin-chin," said Melanie Coffin, a patient representative sitting on the panel, who voted to recommend the drug's approval at the end of a daylong deliberation.
"I'm disappointed," she added after her vote. The drug's effectiveness "is very small and I'd like to see it larger. It's not going to be a perfect drug for everyone. But it will be useful to some."
Panel members weighed Contrave's weight-loss benefits against early signals that it comes with risks that could balloon when it is used for long periods in a large and diverse population of obese patients. The panel returned again and again Tuesday to concerns that subjects taking Contrave routinely experienced increases in blood pressure and, less often, in pulse rates. Those who lost more than 10 percent of their body weight saw improvements in blood pressure from their starting levels. But only a minority of subjects attained such a loss.
Orexigen Therapeutics, the La Jolla, Calif.-based developer of Contrave, told panelists it has plans for a large study to detect adverse reactions to the drug once it is in broad use. The company is also in discussions with the FDA to oversee an additional clinical trial that would pit Contrave against a placebo drug in an effort to detect safety problems.
Several panelists Tuesday insisted that such a trial, while costly and time-consuming, is critical in ensuring the public's safety.