Phase 2b study of Empatic for weight loss

Orexigen Therapeutics announced positive results from its Phase 2b trial for Empatic (bupropion SR/zonisamide SR), its investigational combination drug for the treatment of obesity.  This 24-week, double-blind, randomized trial evaluated 729 patients and incorporated a typical diet and exercise regimen. Patients enrolled in this trial had a body mass index (BMI) of 30 to 45, or as low as 27 in the presence of hypertension or dyslipidemia. The primary endpoint was to show greater weight loss with Empatic compared to its individual components and placebo.

Patients completing 24 weeks of Empatic360 (bupropion SR 360mg/zonisamide SR 360mg) therapy lost 9.9% of their baseline bodyweight, or 22 pounds, compared to 1.7% for placebo patients (p<0.001). Of patients who completed 24 weeks of therapy on Empatic360, 82.6% lost at least 5% of their baseline body weight and 47.7% lost at least 10% of their baseline body weight compared to 18.9% and 5.7% of placebo patients, respectively (p<0.001 for both).
Mean weight loss for Empatic360 was 7.5% versus 2.3% for bupropion 360mg and 5.3% for zonisamide 360mg (p<0.001). Mean weight loss for Empatic120 (bupropion SR 360mg/zonisamide SR 120mg) was 6.1% versus 2.3% for bupropion 360mg and 3.2% for zonisamide 120mg (p<0.001).
Empatic patients experienced significant weight loss as early as their first post-baseline visit at week four.  Additionally, Empatic patients continued to lose weight through the end of the trial period, with no evidence of a weight loss plateau. Improvements were observed in key markers of cardiometabolic risk such as waist circumference, triglycerides, fasting insulin and blood pressure.
Empatic is a fixed combination formulation of zonisamide sustained release (SR) and bupropion SR.  Presently, bupropion is approved for the treatment of depression and for smoking cessation.  Bupropion is believed to increase the brain’s dopamine levels, thus leading to reduced appetites and increases in energy expenditure. Zonisamide is approved for the adjunctive treatment of partial seizures. Zonisamide monotherapy has shown modest weight loss in previously conducted clinical trials.  

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