Study to Evaluate the Effect of Naltrexone and Bupropion Extended-Release Combination on Cardiac Repolarization in Healthy Participants

The drug being tested in this study is called naltrexone HCl/bupropion HCl (NB). NB is approved by the U.S. Food and Drug Administration (FDA) in addition to a reduced-calorie diet and increased physical activity for chronic weight management in adults who are obese or who are overweight and have at least one additional weight-related condition such as high blood pressure, diabetes or high cholesterol. This study is conducted to determine the potential effect of NB relative to placebo on cardiac repolarization. The study will enroll approximately 84 participants. Participants will be randomly assigned (by chance, like flipping a coin) to 1 of 6 treatment sequences, which will remain undisclosed to the participant and study doctor during the study (unless there is an urgent medical need): * Naltrexone/Bupropion + Placebo + Moxifloxacin * Placebo + Moxifloxacin + Naltrexone/Bupropion * Moxifloxacin + Naltrexone/Bupropion + Placebo * Naltrexone/Bupropion + Moxifloxacin + Placebo * Placebo + Naltrexone/Bupropion + Moxifloxacin * Moxifloxacin + Placebo + Naltrexone/Bupropion This study is consisted of 3 periods separated by a washout period (Days 11 through 25). Participants will be admitted to the clinic on Day -2 (Check-in) of each study period and will remain confined to the clinic until the morning of Day 12 of each study period. On Day -1 and Day 11 of each period, participants will undergo 24 hour Holter recordings using an ambulatory electrocardiograph recorder. This single center trial will be conducted in the United States. The overall time to participate in this study is approximately 96 days.