Second phase of a double-blind study clinical trial on Sibutramine for the treatment of patients suffering essential obesity: 6 months after treatment cross-over.

Objective: To evaluate the weight gain after Sibutramine 10 mg daily discontinuation. To evaluate the effect of Sibutramine 10 mg daily in patients who were on a diet for 6 months.

Design: After a double-blind, placebo-controlled, parallel, prospective phase for 6 months, the treatments were crossed over and the patients continued in double-blind observation for another 6-month period.

Subjects: Forty out of 44 patients who were on Sibutramine and 42/44 who were on placebo switched the trial medication. All the patients were obese at the beginning of the trial (body mass index, BMI>30 kg/m(2)). During the first phase, the weight loss in the Sibutramine group was 7.52 kg (95% confidence intervals (95% CI) 6.15; 8.9) and that in the placebo group 3.56 kg (95% CI 2.41; 4.7) (using last observation carried forward (LOCF)).

Measurements: Body weight, BMI, waist, medical history, assessment of hunger, satiety and diet compliance, standard laboratory assessments, blood pressure, heart rate and ECG.

Results: Thirty out 40 patients in the Sibutramine/placebo (S/P) group and 32 out of 42 in the placebo/Sibutramine (P/S) group completed the second phase of the trial. During the second part of the trial the S/P gained 3.21 (95% CI 2.15; 4.26) kg, 1.21 (0.82; 1.59) kg/m(2), and 2.83 (1.55; 4.12) waist cm. The P/S group lost 1.62 (2.62; 0.61), 0.67 (1.09; -0.25) kg/m(2), and 1.85 (3.18; 0.53) waist cm. Eleven patients in the S/P group suffered 14 adverse events, mainly blood pressure increase (n=4); 19 patients in the P/S group had 29 adverse events, mainly dry mouth (n=8), constipation (n=5) and blood pressure increase (n=4). Only one P/S patient withdrew because of an adverse event.

Conclusions: After Sibutramine discontinuation patients had weight gain but they did not reach the baseline body weight. No significant adverse events presented after Sibutramine discontinuation. When Sibutramine was administrated to patients after 6 months of diet, the weight plateau was broken. Early Sibutramine administration had better effects than late post-diet administration. Sibutramine was well tolerated by the patients.