Sibutramine: A new obesity agent enters the marketplace

Sibutramine was approved by the Food and Drug Administration in 1997 and will be marketed as Meridia(R) in early 1998. Sibutramine is a potent reuptake inhibitor of norepinephrine, serotonin, and dopamine-albeit, its ability to inhibit dopamine reuptake is much lower than the other monoamines. Since its two active metabolites have elimination half-lives of 14 and 16 hours, the drug is suitable for once-a-day dosing. Sibutramine reduces food intake in animals and this effect is mediated centrally. It also increases energy expenditure in rats with metabolic rate increases up to 30% above control levels. Animal studies demonstrate that the drug is unlikely to have serious abuse potential; still it is classified as schedule IV. The recommended dosage is 5 to 15 milligrams daily. In a study of 1047 patients, mean weight loss at 24 weeks for 5, 10, and 15 milligrams was 3.1, 4.4, and 5.3 kilograms, respectively. The common side effect profile is similar to other sympathomimetic anti-obesity agents. Dry mouth, constipation, and insomnia generally abate in a few weeks. Sibutramine is associated with mean increases of blood pressure (2-5 mm mercury) and pulse (3-6 beats/minute). Approximately 2% of patients may require discontinuation for tachycardia or clinical hypertension. Sibutramine is not thought to be associated with cardiac valve dysfunction based on a study of 210 patients. Conclusion With careful prescription and conscientious monitoring sibutramine can benefit patients who might otherwise not achieve successful weight loss and associated health benefits.