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Modest Effects On Weight Loss Seen With Orlistat And Sibutramine

Little long-term data is available on the efficacy of anti-obesity agents on weight loss, however, evidence shows modest effects with orlistat and sibutramine after at least 1 year of treatment.

R. Padwal, MD, and colleagues from the University of Alberta Hospital, Canada, conducted a meta-analysis of double-blind, randomised controlled trials of approved anti-obesity agents with follow-up of at least 1 year. Eleven trials of orlistat (n=6021) and 3 trials of sibutramine (n=929) met study criteria.

The 6021 orlistat-treated patients averaged a body mass index (BMI) of 35.7 kg/m² and weight of 100 kg. Standard dose of orlistat (120 mg t.i.d.) was used in all trials. The 929 sibutramine-treated patients had an average BMI of 33.4 kg/m² and weight of 96 kg. Starting dose in 2 trials was 5 mg/day and was increased to 20 mg daily by week 8. In the third trial, the patients received either 10 mg or 15 mg.

Patients in all trials reported weight loss. Pooled analysis of the orlistat trials showed a weight loss of 2.7 kg. Patients treated by orlistat achieved at least 5% weight loss compared to placebo, and 12% of patients achieved at least a weight loss of at least 10%. Similarly, pooled analysis of the sibutramine-treated patients showed a weight loss of 4.3 kg. Compared to placebo, 34% more patients treated with sibutramine achieved a weight loss of at least 5% and 15% achieved a weight loss of at least 10%.

Side effects included gastrointestinal problems with orlistat and increased blood pressure and pulse rate with sibutramine.

This study found that orlistat and sibutramine are the most extensively studied anti-obesity drugs, are associated with high attrition rates (33% for orlistat and 48% for sibutramine), and offer modest efficacy in promoting and maintaining weight loss. The authors conclude that until longer and more rigorous studies are done to evaluate such important outcomes as mortality and cardiovascular morbidity associated with obesity, prevention that is primarily based on nonpharmacologic methods should remain the focus of management with drug therapy considered only on an individual basis.

International Journal of Obesity 2003 Sep 16;[Epub ahead of print]. "Long-term pharmacotherapy for overweight and obesity: a systematic review and meta-analysis of randomized controlled trials"

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