Characterization of the effect of naltrexone/bupropion on body composition

Oral treatment extended-release naltrexone/bupropion (NB) leads to significant weight loss, but its effect on body composition remains unclear. We investigated changes in body composition with dual-energy x-ray absorptiometry after treatment with NB or placebo in a subgroup of participants from a randomized control phase 3 study (COR-I).

Observed changes from baseline to week 52 were estimated for total, lean, and fat mass. Changes in body composition were evaluated using linear regression and adjusted for baseline covariates.

The analysis included 82 participants (placebo, n = 26; NB, n = 56) with comparable baseline characteristics (age, BMI, sex). The NB group experienced a significant -7.8% change of total mass (-12.9% change in fat mass and -4.1% in lean mass), compared with a -2.8% change of total mass (-4.8% change in fat mass and -1.4% in lean mass) in the placebo group. The adjusted changes in lean-to-fat mass ratio of 0.069 in the NB group and -0.056 in the placebo group were significantly different (p < 0.05).

NB-induced weight loss is associated with significant reductions in total percent fat mass, increase in total percent lean mass, and change in lean-to-fat mass ratio, in comparison to placebo. Larger studies are needed to further elucidate the clinical significance of these changes and impact of a potentially healthier metabolism.