The Pharmaceutical Journal
Vol 273 No 7315 p305
4 September 2004

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New cannabinoid receptor blocker found effective in obesity

Treating obesity with the selective cannabinoid-1 receptor blocker rimonabant is significantly more effective than reducing calorie intake alone, reveals a new study presented at the European Society of Cardiology conference in Munich this week.

The study, RIO-EUROPE (Rimonabant in Obesity Europe), compared rimonabant with placebo in 1,507 obese or overweight people. All were advised to follow a mildly hypocalorific diet and to be physically active.

Results after one year showed that patients taking rimonabant (20mg/day) lost an average of 8.6kg compared with 3.6kg for those taking placebo (P<0.001). Those randomised to rimonabant 5mg lost 4.8kg.

More than one-third (39 per cent) of patients on the higher dose of rimonabant lost more than 10 per cent of their initial body weight, compared with 12.4 per cent of the placebo group (P<0.001).

Reporting the results, Luc Van Gaal, professor of diabetology, University Hospital Antwerp, Belgium, noted that a 10 per cent loss of body weight was generally deemed necessary to reduce significantly the cardiovascular risk associated with obesity.

Metabolic risk factors also improved. The number of patients with metabolic syndrome (a cluster of cardiovascular risk factors including dyslipidaemia and hypertension) halved from 42.2 per cent at baseline to 19.6 per cent in the rimonabant 20mg group (P<0.001). HDL-cholesterol increased by 27 per cent, compared with 17.3 per cent in the placebo group. Triglyceride levels also improved. Weight loss accounted for only half of the improvement seen in triglycerides, indicating a direct effect of rimonabant on lipid metabolism, independent of weight loss.

Side effects with rimonabant were mainly mild and transient.