Combination therapy with naltrexone and bupropion for obesity reduces total and visceral adiposity

The effects of combination naltrexone/bupropion therapy on body composition and visceral adipose tissue (VAT) mass were examined in a subset (n = 107) of obese subjects from a Phase 2 trial that compared the efficacy and safety of placebo, naltrexone monotherapy, bupropion monotherapy or one of three naltrexone/bupropion dose combinations for 24 weeks. Body composition data were obtained using dual-energy X-ray absorptiometry and computed tomography. Eighty subjects completed the substudy. Naltrexone/bupropion resulted in weight loss and a greater reduction in body fat (-14.0 ± 1.3%) than placebo (-4.0 ± 2.0%), naltrexone monotherapy (-3.2 ± 2.5%) and bupropion monotherapy (-4.1 ± 2.9%; all p < 0.01). Reduction in VAT mass was also greater with naltrexone/bupropion (-15.0 ± 1.8%) than placebo (-4.6 ± 2.7%), naltrexone monotherapy (-0.1 ± 3.5%) and bupropion monotherapy (-2.3 ± 4.2%; all p < 0.01). Reductions in body fat and VAT mass with naltrexone/bupropion were proportional with weight loss. Weight loss with naltrexone/bupropion was not associated with a greater relative reduction in lean mass than placebo or the monotherapies.