Sanofi-Aventis, the newly merged French pharmaceuticals group, yesterday learnt that a drug it is developing has been effective in reducing weight in its largest clinical trial so far.

Obese patients on the highest dose of the drug, Rimonabant, lost an average of 8.6kg over a year and reduced their waist size by 8.5cm. The results of the phase III trials - the final stage before the company can seek approval to market the drug - were unveiled at the annual congress of the European Society of Cardiology in Munich, Germany.