Sibutramine on weight loss and blood pressure - Medication and Cardiac Factors

Nutrition Research Newsletter, Oct, 2003

Obesity is a chronic disease, and its incidence is increasing worldwide. Physicians have been reluctant to adopt the pharmacological approach for the treatment of obesity because of serious side effects and potential abuse. However, obesity is not merely a cosmetic issue, but an issue of major public health concern. Thus, the long-term management of obesity through a multidisciplinary approach is necessary. In particular, the importance of pharmacological treatment has been reassessed positively in recent years.

Sibutramine was approved in 1997 by the FDA in the United States. It is a seratonin-norepinephrine reuptake inhibitor that induces weight loss by enhancing satiety and by promoting energy expenditure. Sibutramine has also been shown to lower blood sugar and lipid levels. However, it has been reported that because of its norepinephrine effect, sibutramine could increase blood pressure, which would inevitably restrict its use in patients with hypertension. Some recent studies have suggested that sibutramine does not significantly increase blood pressure as compared with a placebo. No meta-analysis has been performed on the effect of sibutramine on blood pressure, although a number of systematic reviews have demonstrated sibutramine's weight-loss effect. However, because obese patients frequently have high blood pressure, the researchers believe that a systematic review of the effect of sibutramine on blood pressure was necessary. The purpose of the current study was to provide a comprehensive meta-analysis of randomized, controlled trials on the effect of sibutramine on blood pressure and weight loss.

Twenty-one placebo-controlled, double-blind, randomized trials of sibutramine were identified using MEDLINE, EMBASE, and a manual search. The effect size of sibutramine was defined as the standardized difference of changes in weight and blood pressure between the treatment and the control groups. The effect sizes of sibutramine on weight and systolic and diastolic blood pressure (DBP) changes were estimated. Subgroup analysis were undertaken to explore the relationship between effect sizes and the study characteristics. Sibutramine was found to have a large effect on weight loss, but increased blood pressure significantly.

A greater increase in systolic blood pressure was observed in younger people (< 44 years old) and in larger trials (greater than or equal to 120 participants). People who were heavier (greater than or equal to 92 kg) experienced a significantly greater increase in DBP. The overall effect sizes on increased systolic blood pressure were significantly larger when the initial body weight was greater than or equal to 92 kg and the age was <44 years; similarly, the effect sizes on increased diastolic blood pressure were significantly larger when the initial weight was greater than or equal to 92 kg.

The researchers concluded that sibutramine has a large effect on weight loss and causes a small, but significant, increase in both systolic blood pressure and diastolic blood pressure. It might be considered that the small increase in blood pressure is not important in the clinical setting in nor-motensive patients or patients with well control hypertension. However, sibutramine should be used cautiously in patients with borderline or high blood pressure, because a slight increase in blood pressure is crucially important.

S Kim, Y Lee, S Jee, C Nam. Effect of Sibutramine on Weight Loss and Blood Pressure: A Meta-analysis of Controlled Trials. Obes Res 11(9):1116-1123 (September 2003). [Correspondence: Chung Mo Nam, Department of Preventive Medicine and Public Health, Yonsei University College of Medicine #134 Shinchon-dong Seodaemun-gu, Seoul 120-752, Republic of Korea. E-mail: cmnam@yumc.yonsei.ac.kr]