A proprietary fixed dose combination of naltrexone sustained-release and bupropion, which is used to manage obesity by regulating the energy balance.
Adverse effects Nausea, headache, dizziness, dry mouth.
Putative mechanism of action Bupropion acts by stimulating centrally-projecting neurons which contain peptides derived from pro-opiomelanocortin–POMC. POMC neurons–PN have direct projections to the hypothalamus, which plays a major role in regulating appetite. Naltrexone prevents inhibition of PNs by blocking the action of beta-endorphin. PNs release alpha-melanocyte-stimulating hormone–alpha-MSH, which binds to the melanocortin 4–MC4 receptor, triggering a cascade, resulting in reduced food intake and increased energy expenditure. The ability of naltrexone to block this inhibitory feedback loop is believed to facilitate a more potent and longer-lasting activation of PNs, thus amplifying the putative effects on energy balance. Co-administration of bupropion and naltrexone is believed to produce a greater effect on the PN firing rate than either compound acting alone, suggesting that the two act synergistically.