Clinical pharmacotherapy for obesity: current drugs and those in advanced development

The current obesity pandemic imposes a major global disease burden. Levels of non-communicable diseases such as type 2 diabetes, cardiovascular disease and some cancers will continue to rise unless an effective approach to treat obesity is found. Sustained weight loss of between 5-10% in the obese, by various means, confers marked health benefits. The currently available pharmacotherapies, orlistat and sibutramine, can induce weight loss of between 5-10% over 2 years or more. In trials, orlistat and sibutramine induced weight loss tends to be only between 2-4 kg greater than that produced by placebo control. However, this additional placebo subtracted weight loss produces marked additional improvements in diabetes and cardiovascular risk factors. Moreover, in the 4 year long XENDOS trial, the modest placebo subtracted weight loss produced by orlistat (2.8 kg) reduced the incidence of diabetes by over a third in those with normal glucose tolerance, and by nearly half in those with impaired glucose tolerance. Despite this, prescription sales of sibutramine in the US have apparently remained static and those of orlistat have fallen, with the drug now entering the global over-the-counter medication market. Recent data on potential anti-obesity drugs currently under going phase III trials, such as Rimonabant and Topiramate, demonstrate these drugs produce greater and more prolonged weight loss. Wider use of pharmacotherapy and enhanced efficacy for the next generation of anti-obesity drugs certainly promise to reduce obesity related illness if not halt the rise in obesity per se.