Definition

A fixed combination of naltrexone hydrochloride, an opioid antagonist, and bupropion hydrochloride, an aminoketone antidepressant and a weak inhibitor of the neuronal reuptake of dopamine and norepinephrine, that may be used for appetite regulation, weight management and weight loss. Upon oral administration of naltrexone hydrochloride/bupropion hydrochloride, naltrexone binds to and blocks the various opioid receptors in the central nervous system. Bupropion inhibits neuronal reuptake of dopamine and norepinephrine, thereby increasing the level of these neurotransmitters. Bupropion may also have a direct effect on the hypothalamus, the appetite regulatory center. These actions may block the rewarding aspects of food and reduce appetite and food cravings, and contribute to weight loss.