Long-Term Risk-Benefit of Diet Drug Unclear

After reviewing data from 29 studies of the weight loss agent sibutramine, US researchers have concluded that there is still not enough evidence to accurately evaluate the long-term risk-benefit profile of the drug.

After reviewing data from 29 studies of the weight loss agent sibutramine, US researchers have concluded that there is still not enough evidence to accurately evaluate the long-term risk-benefit profile of the drug. A report of the findings, which appears in the Archives of Internal Medicine, indicates that sibutramine is effective at promoting weight loss. However, it is unclear whether the drug actually helps reduce obesity-associated illness and death. Also, the net effect sibutramine has on the risk of developing cardiovascular disease remains to be determined. “Sibutramine was introduced in 1997, so we only have 7 years of experience with this medication,” lead author Dr. David E. Arterburn, from the Cincinnati VA Medical Center in Ohio, told Reuters Health. “In 2002, reports were released in Italy of two cardiovascular-related deaths due to sibutramine. This led to several independent reviews that ultimately concluded” that the benefits of sibutramine outweighed the risks. Since those reviews, however, “16 randomized studies have been published,” Arterburn said. “So we wanted to include these studies in our review to better assess the cardiovascular risks with sibutramine. A total of 29 trials were included in our review.” In trials of 3- and 12-months’ duration, sibutramine produced greater weight loss than placebo. Moreover, in one trial, the weight loss benefits of sibutramine persisted for 2 years. Weight loss with sibutramine was associated with both positive and negative effects on cardiovascular risk factors. Although heart rate and blood pressure increased modestly, slight improvements in cholesterol levels and glycemic control were observed. “The trials we reviewed were not designed or powered to properly follow cardiovascular events,” Arterburn pointed out. As such, “there was not enough valid information to decide whether or not sibutramine had a favorable cardiovascular risk profile.” An international multicenter study is in the works that should help determine the long-term risk-benefit profile of sibutramine, Arterburn said. “But we are still a few years out from having that type of information about the drug,” he said. (Source: Archives of Internal Medicine, May 2004)