A comparison of sibutramine and dexfenfluramine in the treatment of obesity

Objective: Because long-term weight reduction is often unsuccessful with dietary restriction alone, pharmacological agents have been used to promote weight loss. We have compared the novel (multiple monoamine neurotransmitter reuptake inhibitor) antiobesity drug sibutramine (10 mg once daily) with the extensively studied serotonin-releaaing antiobesity agent dexfenfluramine (15 mg twice daily). Research Methods and Procedures: 226 healthy outpatients (aged 18 to 65 years; body mass index greater than or equal to 27 kg/m(2)) were included in a 12-week, randomized, double-blind, parallel group study. The main outcome measures were changes in weight, body mass index, waist and hip circumference and ratio, and safety profiles. Results: Mean (+/-SEM) absolute weight loss was 4.5 +/- 0.4 kg in the sibutramine group (n = 112) and 3.2 +/- 0.3 :kg in the dexfenfluramine group (n = 112) (endpoint analysis); 4.7 +/- 0.4 kg in the sibutramine group (n = 94); and 3.6 +/- 0.3 kg in the dexfenfluramine group (n = 94) (completers analysis). Comparing the two treatments under the conventional null hypothesis of equality as a secondary analysis, weight loss at endpoint in patients receiving sibutramine was significantly greater than that achieved with dexfenfluramine (p<0.05). Both drugs had similar adverse events profiles: 174 patients (77%) experienced adverse events; 17 patients withdrew du to adverse events (sibutramine, n = 6; dexfenfluramine, n = 11). Pulse rate increased significantly in sibutramine-treated patients (3.6 bpm), but decreased in dexfenfluramine-treated patients (-0.9 bpm). Discussion: Sibutramine (10 mg once daily) is at least as effective as dexfenfluramine (15 mg twice daily) in achieving weight loss in patients with obesity.