The mechanism of action of sibutramine, a tertiary amine, involves inhibition of the neuronal uptake of norepinephrine and serotonin at the receptor sites that affect food intake.

More than 600 obese patients were enlisted from local health centers to participate in a weight loss program that included taking sibutramine, along with diet and exercise. Those who achieved at least a 5% weight loss (about 77%) after 6 months were recruited to receive sibutramine or the placebo for 18 more months. Forty-three percent of the sibutramine-treated individuals maintained 80% or more of their original weight loss, compared with 16% of the placebo group. Thus, the research showed that sibutramine is effective in enhancing a low-calorie diet to help maintain weight loss for up to two years. Previous studies had only assessed the medicine’s utility over a one-year period.

During the course of the study, the researchers recorded changes in important metabolic indices. Over all, good results were obtained for sibutramine patients, who showed significant decreases in triglycerides and VLDL cholesterol and increases in the welcome HDL cholesterol. However, no effect was observed on LDL (“bad”) cholesterol levels.

Adverse events did occur, ranging from headache, to insomnia, to higher blood pressure.

Regarding rises in blood pressure, though, the researchers suggest that the metabolic benefits of sibutramine may counteract this occurrence and decrease the absolute risk of heart attack. Further studies assessing this will have to be carried out. Certainly, though, routine blood pressure monitoring for patients receiving the medication is advised.