Samidorphan

Olanzapine is an effective atypical antipsychotic that, like other antipsychotics, is associated with weight gain, metabolic dysfunction, and increased risk of type II diabetes. Samidorphan is a novel opioid antagonist structurally related to naltrexone, with a higher affinity for opioid receptors, more potent μ-opioid receptor antagonism, higher oral bioavailability, and a longer half-life, making it an attractive candidate for oral dosing. Although antipsychotic-induced weight gain is incompletely understood, it is thought that the opioid system plays a key role in feeding and metabolism, such that opioid antagonism may be expected to ameliorate these negative effects. Samidorphan has been shown in animal models and clinical trials to ameliorate olanzapine-induced weight gain and metabolic dysfunction.

Samidorphan was first approved as a variety of fixed-dose combination tablets with olanzapine by the FDA on May 28, 2021, and is currently marketed under the trademark LYBALVI™ by Alkermes Inc.