The Pharmaceutical Journal Vol 267 No 7179 p873-877
22-29 December 2001

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Anti-obesity drug criticised by the DTB but supported by NICE advice

This month's Drug and Therapeutics Bulletin says that it finds sibutramine (Reductil) "difficult to recommend".

The bulletin points to sibutramine's contraindications for use, potential drug interactions and stringent requirements for monitoring as reasons for making the drug "difficult and impractical to use". It adds that sibutramine has limited potential benefit and that supporting trial evidence has serious limitations.

The critical analysis is in contrast to the National Institute for Clinical Excellence's recommendation that sibutramine should be used as part of the overall management of obesity (PJ, 20 October, p541). Andrew Dillon, chief executive of NICE, responded: "The institute considers that sibutramine has a place in treating obesity. We reached this conclusion after an extensive review of the evidence and following widespread consultation, involving organisations that speak for people with the condition and those that represent doctors who treat them." He added: "Sibutramine is not a cure for the condition but some patients will benefit. Since the treatment is both clinically and cost effective, patients should not be denied access to it."

The bulletin concludes that sibutramine produces a weight loss of 5 to 7 per cent of initial body weight when used in combination with dietary advice. "Weight loss is quickly regained after sibutramine is stopped," it adds.

In terms of adverse events, sibutramine can cause increased heart rate and blood pressure, which need to be monitored, the bulletin says. It adds that sibutramine is contraindicated in some conditions that accompany obesity, such as coronary artery disease. In addition, it interacts with drugs that affect cytochrome P450 3A4 and those that increase serotonin levels.

The bulletin criticises the methodology used in many of the trials that support sibutramine's use. It says that most reports used an analysis based on "last observation carried forward" which assumes that the last known trial result recorded for patients who drop out of the study is the same as they would have achieved at the end of the trial. In addition, some trials have only included patients who have lost a certain amount of weight during a non-blinded initial treatment phase. The bulletin also points out that dietary, psychological and exercise interventions used during the trial might not be feasible in clinical practice (2001;39:89).

A spokesman for Abbott Laboratories, manufacturer of sibutramine, told The Journal that the company is disappointed with the content of the bulletin. "It clearly does not reflect the significant health benefit of 5 to 10 per cent weight loss, and the proven efficacy of sibutramine," he said.

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