New Weight-Loss Drug Shows Promise

Trial results look good, but experts say rimonabant isn't a 'magic bullet'

TUESDAY, Feb. 14, 2006 (HealthDay News) -- Men and women who stayed on the experimental weight-loss drug rimonabant for two years managed to lose weight and keep it off, a new study finds.

And as an added bonus, those using rimonabant also showed improved blood levels of cholesterol and triglycerides, the researchers report.

Rimonabant, which will likely be marketed by drug maker Sanofi-Aventis as Accomplia, is currently under review by the U.S. Food and Drug Administration. If approved, it would become the third drug approved for weight loss, after orlistat (Xenical) and sibutramine (Meridia).

"These are the longest results to date," said study author Dr. Xavier Pi-Sunyer, chief of endocrinology at St. Luke's-Roosevelt Hospital Center and a professor of medicine at Columbia University College of Physicians and Surgeons, both in New York City. "Others have been one-year studies. Now we have two-year data which shows maintenance of weight loss."

The study was funded by Sanofi-Aventis.

While Pi-Sunyer believes rimonabant could play a big role in weight loss -- alongside lifestyle and diet changes -- others downplayed the role of the drug.

"I think rimonabant should play a very minimal role," said Dr. Denise Simons-Morton, author of an accompanying editorial and director of the clinical applications prevention program at the National Heart, Lung, and Blood Institute. "I don't think the weight loss they got was any better than what you get from lifestyle, and drugs always have side effects. We should minimize using medications if lifestyle [changes] will serve the purpose."

Both the study and the editorial appear in the Feb. 15 issue of the Journal of the American Medical Association.

Some two-thirds of U.S. adults are overweight or obese, conditions which increase the risk of developing diabetes and cardiovascular disease. Each year, experts say, about 112,000 to 280,000 deaths can be attributed to obesity.

Weight loss -- even a modest decline of 5 percent to 10 percent of body weight -- has been shown to improve risk factors associated with both diabetes and cardiovascular disease, such as cholesterol and blood glucose levels.

"It seems that cutting back this amount is quite helpful in terms of stress on the body," Pi-Sunyer said. "I think that data now is pretty clear."

Rimonabant acts by blocking receptors in the endocannabinoid system, one of the body's pleasure centers -- the same class of centers affected by marijuana. It is the first such drug to be tested.

For this trial, more than 3,000 obese or overweight adults who also had hypertension or dyslipidemia (abnormal blood fat levels) were randomized to receive daily doses of either a placebo, 5 milligrams of rimonabant, or 20 milligrams of rimonabant for one year.

Only 51 percent of the participants in the placebo or 5-milligram rimonabant group finished one year of therapy, the researchers report, and just 55 percent did so in the 20-milligram group.

At the end of the first year of the study, 26.1 percent of patients receiving 5 milligrams of rimonabant achieved a 5 percent or greater weight loss vs. 48.6 percent for patients receiving 20 milligrams of rimonabant, and 20 percent for patients receiving the placebo.

Compared with the placebo group, participants taking the higher dose of rimonabant had greater average reductions in weight, waist circumference and triglyceride levels, along with a greater increase in HDL ("good") cholesterol levels.

The weight loss was comparable to weight loss achieved with either Xenical or Meridia, the researchers added.

At the end of that first year, participants on rimonabant were re-randomized to take either a placebo or continue on rimonabant for a second year. Participants also made diet and exercise changes.

Participants who were switched from 20 milligrams of rimonabant to a placebo gained back the weight they had lost, the researchers said. On the other hand, those who continued on the 20-milligram pill maintained their weight loss.

There were some side effects, the most common of which was nausea.

Outside experts were concerned that other adverse effects might materialize once the drug is taken by a greater number of people and possibly for longer periods of time.

"We still don't know how long people will be on it and we're worried about side effects," Simons-Morton said. "When you get more people on the medication, you discover more effects."

The drop-out rate for the study was also very high, with only about half the people in each treatment group staying on the drug, she said. Calculations were based only on those who took the drug, not on the original number in the study.

"That's an extremely high drop-out rate," Simons-Morton said. "Doing those kinds of educated guesses to pick values isn't nearly as good as actually having measurements. I don't know if their assumptions are correct or not. If you want to know what the results of a drug will be, you have to take into account everyone it's prescribed for and not just the people who take it."

Overall, Simons-Morton said, the evidence for pharmaceuticals trumping lifestyle change for effective weight loss is less than overwhelming.

"People are looking for magic bullets and things are much more complicated than that," she said. "Human biology and life in society is just more complex than that. Lifestyle is the preferred way to go. The drug may be useful in some people if they are successful early on in lifestyle and start to gain weight back."

More information

For more on obesity, head to the U.S. Centers for Disease Control and Prevention.

SOURCES: F. Xavier Pi-Sunyer, M.D., chief, endocrinology, St. Luke's-Roosevelt Hospital Center, and professor, medicine, Columbia University College of Physicians and Surgeons, both in New York City; Denise G. Simons-Morton, M.D., Ph.D., director, clinical applications and prevention program, National Heart, Lung, and Blood Institute; Feb. 15, 2006, Journal of the American Medical Association
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