Effect of combined GLP-1 analogue and bupropion/naltrexone on weight loss: a retrospective cohort study

Little is known about the effect of a multi-drug weight loss strategy in obesity treatment, particularly combining bupropion/naltrexone and glucagon-like peptide 1 (GLP-1) analogue. The purpose of this study was to evaluate if there are any additive effects of prescribing bupropion/naltrexone on top of GLP-1 analogue as weight loss therapy. This was a retrospective cohort study of adult patients with a body mass index (BMI) ≥ 30 kg/m2 prescribed GLP-1 analogue therapy at an obesity specialist clinic in Vancouver, Canada. We compared a 6 and 12-month change in total body weight loss (TBWL) for those receiving monotherapy from the initiation of GLP-1 analogue therapy with those receiving combination therapy from the initiation of bupropion/naltrexone added-on therapy. Patients prescribed combination therapy were stratified into responder (loss of ≥ 5% TBWL) and non-responder (TBWL < 5%) subgroups based on initial response to the GLP-1 analogue alone for any amount of time. The mean weight loss among patients prescribed GLP-1 analogue monotherapy at 12 months was 11.42 kg, SD 9.95 (9.6% TBWL). There was no significant difference between these two treatment strategies overall (HR 0.88, 95% CI 0.68 to 1.14, p = 0.35). However, when stratified by response to initial GLP analogue therapy, the addition of bupropion/naltrexone was associated with a statistically significant reduction in weight in both the responder (4.3% TBWL (p < 0.01)) and non-responder groups (4.0% TBWL (p < 0.01)). GLP-1 analogues are an effective treatment for weight loss, and the addition of bupropion/naltrexone is associated with greater weight loss including in patients who are initially non-responsive to GLP-1 analogues.