Study Shows Heart Promise for New Weight-Loss Drug

By Paula Rasich

(CardioSmart) Marketed as Acomplia in Europe, the prescription drug rimonabant appears to promote weight loss, shrink stomach fat, boost good HDL cholesterol and control blood sugar levels, according to the latest findings from the RIO-Europe study (European Heart Journal, Apr 15, 2008).

Being overweight seems to disrupt the normal metabolism of fats, and raises blood sugar and blood pressure. Along with excessive weight around the abdomen, this cluster of risk factors is often referred to as metabolic syndrome and is linked to the development of heart disease and diabetes. International researchers are now investigating a possible solution. 

In this ongoing phase III clinical trial, more than 1,500 overweight and obese patients were randomized to receive a placebo, 5 mg or 20 mg of rimonabant once daily for two years as an aid to weight loss.  40% of the participants in each group dropped out, with 886 completing the full course of the study. Side effects included anxiety, depression and gastrointestinal disorders. After two years, researchers from Antwerp University Hospital in Belgium found that those who got the highest dose of rimonabant achieved and maintained a weight loss of 28 pounds, compared with 17 pounds in the placebo group. And those who took the highest dose of the drug lost significantly more inches from their waist compared to the placebo group.

What’s more, levels of good HDL cholesterol rose 22 percent and triglycerides fell four percent in those who were treated with the highest dose. Improved insulin sensitivity and better blood sugar control was also seen in that group. “The positive effects are broad,” says cardiologist Christopher Cannon, MD, associate professor of medicine at Harvard Medical School in Boston. “But the patients who would probably benefit the most are obese people with diabetes or metabolic syndrome.”

Rimonabant is the first in a new class of drugs called selective CB1 receptor blockers that work by affecting sugar and fat metabolism through the endocannabinoid system (ECS). CB1 receptors are found in fat tissue, the liver, pancreas, digestive tract, muscle, and in various regions of the brain. Drugs that target the ECS can increase the risk of depression and anxiety in people who may be vulnerable. A higher risk for developing mood disorders was shown in previous trials. The FDA has not approved this new medication because long-term effects are still unknown, but rimonabant has been available in Europe since 2006. More studies are underway, and the pharmaceutical maker Sanofi Aventis may apply for FDA approval in the near future.

SOURCES:

Van Gaal et al. Long Term effect of CB1 blockade with rimonabant on cardiometabolic risk factors: two year results from the RIO-Europe Study. European Heart Journal April 2008.

Christopher P. Cannon, MD, Associate Professor of Medicine, Harvard Medical School, Boston, MA.