Sep 13 2004

Latest findings remain impressive By DrRich

At the recent European Society of Cardiology Congress, new data was reported on the effectiveness of rimonabant for treating obesity. Rimonabant, an investigational drug from Sanofi-Aventis, is aimed at helping patients lose weight and quit smoking. Early trials with rimonabant have been promising.

In this most recent trial, the RIO-EUROPE trial, 1507 overweight and obese patients were randomized to receive either placebo or one of two doses of rimonabant (5 mg or 20 mg per day.). Patients taking 20 mg rimonabant had significant weigh loss, and also improvement in lipid profiles, compared to patients on placebo. (Those taking 5 mg also had more weight loss than placebo patients, but the magnitude of weight loss was much less.) In addition, waist measurements significantly improved in rimonabant patients.

In those taking the 20 mg dose, almost 40% of patients lost 10% of their baseline body weight, HDL cholesterol (the good cholesterol) increased by 27%, and triglycerides decreased by 10%. Furthermore, the number of patients with metabolic syndrome was cut by half among patients taking 20 mg rimonabant.

Only about 50% of the remarkable metabolic improvement seen among rimonabant patients could be accounted for by the weight loss itself. Investigators conclude that rimonabant must have a direct favorable effect on lipid metabolism.

Is rimonabant too good to be true?
That remains to be seen. While the benefits of rimonabant appear to be stacking up, the downside is also becoming more apparent. About one of three patients in the RIO-EUROPE trial quit taking rimonabant because of side effects (the most common being nausea, dizziness, and diarrhea.) And during another session at the European Congress, rimonabant (which generally improved quality of life) was noted to cause amnesia and depression in a small number of patients. ( Read about this quality of life study here.)

Before this drug is marketed, its long-term effects (both good and bad) will need to be teased out. Results from a long-term study with rimonabant, due to be revealed in November, ought to be a major step in this regard. If these results are favorable it is expected that Sanofi-Aventis may apply for drug approval sometime in 2005.