The relationship between early weight loss and weight loss at 1 year with naltrexone ER/bupropion ER combination therapy

Abstract

Background/Objectives: Weight management medications increase the likelihood that patients will achieve clinically meaningful improvements in cardiovascular, metabolic and other weight-related measures of health. However, the weight loss achieved with any weight management intervention can vary widely among individuals, and patients who do not respond to pharmacotherapy by achieving clinically meaningful weight loss should discontinue therapy. We characterized 1-year weight loss in the phase 3 clinical trial program of the weight management medication, naltrexone/bupropion 32/360 mg (NB), as well as the relationship between early weight loss and long-term weight loss, particularly with respect to participants who achieved the clinically recommended threshold of ≥5% weight loss by Week 16. Participants/Methods: Data from participants from each of the four phase 3, randomized, placebo-controlled, 56-week clinical trials with NB were pooled (modified intent-to-treat population; NB N=2043, Placebo N=1319). This exploratory analysis examined the relationship between participant achievement of various weight loss thresholds early in treatment (at Week 8, 12 or 16) and the associated weight loss at Week 56 (Completers population; NB N=1310, Placebo N=763). Results: In the NB participants who completed 1 year of treatment, weight loss of at least 5% at Week 16 (n=873) was associated with least-squares mean weight loss of 11.7% at Week 56 and 85% of these participants had Week 56 weight loss of ≥5%. Eighty percent (95% confidence interval: 78-82%) of the participants who would, and would not, achieve ≥5% weight loss at Week 56 were correctly identified using the clinically recommended threshold of ≥5% at Week 16. Safety and tolerability of NB was similar to previously published reports. Conclusions: Participants who meet the Week 16 threshold of ≥5% weight loss are likely to maintain clinically significant weight loss after 1 year of treatment. Further evaluations are required to evaluate improvements in measures of cardiovascular and metabolic risk.