This 56-week, randomized, placebo-controlled trial examined the efficacy and safety of naltrexone plus bupropion as an adjunct to intensive behavior modification (BMOD). A total of 793 participants (BMI = 36.5 ± 4.2 kg/m2) was randomly assigned in a 1:3 ratio to: (i) placebo + BMOD (N = 202); or (ii) naltrexone sustained-release (SR, 32 mg/day), combined with bupropion SR (360 mg/day) plus BMOD (i.e., NB32 + BMOD; N = 591). Both groups were prescribed an energy-reduced diet and 28 group BMOD sessions. Co-primary end points were percentage change in weight and the proportion of participants who lost ≥5% weight at week 56. Efficacy analyses were performed on a modified intent-to-treat population (ITT; i.e., participants with ≥1 postbaseline weight while taking study drug (placebo + BMOD, N = 193; NB32 + BMOD, N = 482)). Missing data were replaced with the last observation obtained on study drug. At week 56, weight loss was 5.1 ± 0.6% with placebo + BMOD vs. 9.3 ± 0.4% with NB32 + BMOD (P < 0.001). A completers analysis revealed weight losses of 7.3 ± 0.9% (N = 106) vs. 11.5 ± 0.6% (N = 301), respectively (P < 0.001). A third analysis, which included all randomized participants, yielded losses of 4.9 ± 0.6 vs. 7.8 ± 0.4%, respectively (P < 0.001). Significantly more NB32 + BMOD- vs. placebo + BMOD-treated participants lost ≥5 and ≥10% of initial weight, and the former had significantly greater improvements in markers of cardiometabolic disease risk. NB32 + BMOD was generally well tolerated, although associated with more reports of nausea than placebo + BMOD. The present findings support the efficacy of combined naltrexone/bupropion therapy as an adjunct to intensive BMOD for obesity.

The neurohormonal control of body weight involves a complex interplay between long‐term adiposity signals (e.g., leptin), and short‐term satiation signals (e.g., amylin). In diet‐induced obese (DIO) rodents, amylin/leptin combination treatment led to marked, synergistic, fat‐specific weight loss. To evaluate the weight‐lowering effect of combined amylin/leptin agonism (with pramlintide/metreleptin) in human obesity, a 24‐week, randomized, double‐blind, active‐drug‐controlled, proof‐of‐concept study was conducted in obese or overweight subjects (N = 177; 63% female; 39 ± 8 years; BMI 32.0 ± 2.1 kg/m2; 93.3 ± 13.2 kg; mean ± s.d.). After a 4‐week lead‐in period with pramlintide (180 µg b.i.d. for 2 weeks, 360 µg b.i.d. thereafter) and diet (40% calorie deficit), subjects achieving 2–8% weight loss were randomized 1:2:2 to 20 weeks of treatment with metreleptin (5 mg b.i.d.), pramlintide (360 µg b.i.d.), or pramlintide/metreleptin (360 µg/5 mg b.i.d.). Combination treatment with pramlintide/metreleptin led to significantly greater weight loss from enrollment to week 20 (−12.7 ± 0.9%; least squares mean ± s.e.) than treatment with pramlintide (−8.4 ± 0.9%; P < 0.001) or metreleptin (−8.2 ± 1.3%; P < 0.01) alone (evaluable, N = 93). The greater reduction in body weight was significant as early as week 4, and weight loss continued throughout the study, without evidence of a plateau. The most common adverse events with pramlintide/metreleptin were injection site events and nausea, which were mostly mild to moderate and decreased over time. These results support further development of pramlintide/metreleptin as a novel, integrated neurohormonal approach to obesity pharmacotherapy.

OBJECTIVE -To assess the efficacy and safety of pramlintide in patients with type 2 diabetes suboptimally controlled with basal insulin.RESEARCH DESIGN AND METHODS -In a 16-week, double-blind, placebocontrolled study, 212 patients using insulin glargine with or without oral antidiabetes agents (OAs) were randomized to addition of pramlintide (60 or 120 g b.i.d./t.i.d.) or placebo. Insulin glargine was adjusted to target a fasting plasma glucose concentration of 70 -100 mg/dl. One coprimary end point was the change in A1C at week 16. The other coprimary end point was a composite measure of overall diabetes control comprising A1C Յ7.0% or reduction Ն0.5%, mean daily postprandial glucose (PPG) increments Յ40 mg/dl, no increase in body weight, and no severe hypoglycemia. Patients meeting all four conditions at week 16 achieved this end point.RESULTS -More pramlintide-than placebo-treated patients achieved the composite end point (25 vs. 7%; P Ͻ 0.001). Reductions (means Ϯ SE) in A1C (Ϫ0.70 Ϯ 0.11% vs. Ϫ0.36 Ϯ 0.08%; P Ͻ 0.05) and PPG increments (Ϫ24.4 Ϯ 3.6 mg/dl vs. Ϫ0.4 Ϯ 3.0 mg/dl; P Ͻ 0.0001) were greater in pramlintide-versus placebo-treated patients, respectively. Glycemic improvements were accompanied by progressive weight loss with pramlintide and weight gain with placebo (Ϫ1.6 Ϯ 0.3 kg vs. ϩ0.7 Ϯ 0.3 kg; P Ͻ 0.0001). No treatment-related severe hypoglycemia occurred.CONCLUSIONS -Pramlintide improved multiple glycemic parameters and reduced weight with no increase in hypoglycemia in patients with type 2 diabetes who were not achieving glycemic targets with basal insulin with or without OAs.

Circulating levels of the pancreatic beta-cell peptide hormone amylin and the gut peptide PYY[3-36] increase after nutrient ingestion. Both have been implicated as short-term signals of meal termination with anorexigenic and weight-reducing effects. However, their combined effects are unknown. We report that the combination of amylin and PYY[3-36] elicited greater anorexigenic and weight-reducing effects than either peptide alone. In high-fat-fed rats, a single ip injection of amylin (10 microg/kg) plus PYY[3-36] (1000 microg/kg) reduced food intake for 24 h (P < 0.05 vs. vehicle), whereas the anorexigenic effects of either PYY[3-36] or amylin alone began to diminish 6 h after injection. These anorexigenic effects were dissociable from changes in locomotor activity. Subcutaneous infusion of amylin plus PYY[3-36] for 14 d suppressed food intake and body weight to a greater extent than either agent alone in both rat and mouse diet-induced obesity (DIO) models (P < 0.05). In DIO-prone rats, 24-h metabolic rate was maintained despite weight loss, and amylin plus PYY[3-36] (but not monotherapy) increased 24-h fat oxidation (P < 0.05 vs. vehicle). Finally, a 4 x 3 factorial design was used to formally describe the interaction between amylin and PYY[3-36]. DIO-prone rats were treated with amylin (0, 4, 20, and 100 microg/kg.d) and PYY[3-36] (0, 200, 400 microg/kg.d) alone and in combination for 14 d. Statistical analyses revealed that food intake suppression with amylin plus PYY[3-36] treatment was synergistic, whereas body weight reduction was additive. Collectively, these observations highlight the importance of studying peptide hormones in combination and suggest that integrated neurohormonal approaches may hold promise as treatments for obesity.

Pramlintide, the first member of a new class of drugs for the treatment of insulin-using patients with type 2 or type 1 diabetes mellitus, is an analog of the peptide hormone amylin. Amylin is co-secreted with insulin from pancreatic beta cells and acts centrally to slow gastric emptying, suppress postprandial glucagon secretion, and decrease food intake. These actions complement those of insulin to regulate blood glucose concentrations. Amylin is relatively deficient in patients with type 2 diabetes, depending on the severity of beta-cell secretory failure, and is essentially absent in patients with type 1 diabetes. Through mechanisms similar to those of amylin, pramlintide improves overall glycemic control, reduces postprandial glucose levels, and reduces bodyweight in patients with diabetes using mealtime insulin. Reductions in postprandial glucose and bodyweight are important, since postprandial hyperglycemia is associated with an increased risk of microvascular and macrovascular complications, and increased weight is an independent risk factor for cardiovascular disease. Pramlintide is generally well tolerated, with the most frequent treatment-emergent adverse event being mild to moderate nausea, which decreases over time. Pramlintide treatment is also associated with improvements in markers of oxidative stress and cardiovascular risk and improved patient-reported treatment satisfaction. These factors make pramlintide an attractive option for the treatment of postprandial hyperglycemia in patients with diabetes using mealtime insulin.