Long-term data needed on anti-obesity drugs

NEW YORK (Reuters Health) - The safety and efficacy over the long term need to be documented for Xenical (known generically as orlistat), Meridia (sibutramine) and Acomplia (rimonabant) before doctors can be certain that the benefits of these anti-obesity drugs outweigh the risks, according to a commentary appearing in The Lancet medical journal.

Orlistat and sibutramine are currently approved for long-term use, while rimonabant is under review by the US Food and Drug Administration.

Orlistat reduces weight by an average of 3 kilograms, whereas sibutramine and rimonabant each reduce weight by 4 kg to 5 kg, on average, Dr. Raj S. Padwal and Dr. Sumit R. Majumdar, from the University of Alberta Hospital in Edmonton, Canada, note in their article.

However, each of the agents carry potentially important adverse effects, the authors note. Treatment with orlistat is associated with frequent gastrointestinal side effects, sibutramine may raise blood pressure and heart rate, and rimonabant may increase the risk of mood disorders.

These adverse effects are typically apparent during short-term use. The greater concern, according to the authors, is what will occur with long-term use. Padwal and Majumdar comment that research on anti-obesity agents is plagued by high drop-out rates and by a lack of data on long-term illnesses and deaths.

"In light of the lack of successful weight loss-treatments and the public-health implications of the obesity pandemic, the development of safe and effective drugs should be a priority," the researchers state.

However, they say antiobesity drug trials showing important reductions in obesity-related illness and mortality "should be required either before these drugs are approved for widespread use or as a condition of ongoing approval."

SOURCE: Lancet, January 6, 2007.