Olanzapine/Samidorphan: A New Option for the Treatment of Adults With Schizophrenia or Bipolar I Disorder

Objective:
To review the pharmacology, pharmacokinetics, and efficacy and safety data of a combination of olanzapine and samidorphan (OLZ/SAM) for the treatment of schizophrenia and bipolar I disorder, which mitigates the possible unwanted side effects of weight gain associated with olanzapine (OLZ).
Data Sources:
The review was done with a bibliographic survey of studies using MEDLINE/PubMed (January 1999-May 2021) database using the keywords olanzapine and samidorphan. Abstracts, scientific posters, and information from the manufacturer’s product labeling were evaluated for inclusion. Inclusion criteria: phase 2, phase 3, and open-labeled studies that evaluated the use of OLZ/SAM for the treatment of schizophrenia and bipolar I disorder.
Data Synthesis:
We have included one phase 2 dose-ranging exploratory study, two phase 3 efficacy and safety studies, and several open-label extension studies without a comparator. For the treatment of schizophrenia, OLZ/SAM and OLZ alone were analyzed in 2 randomized, double-blind comparison studies of approximately 960 patients. Analysis indicated that OLZ (5-20 mg)/SAM (10 mg) significantly mitigated the side effect of weight gain compared with OLZ alone (control) while maintaining antipsychotic efficacy. For bipolar I disorder, OLZ/SAM was approved as an acute treatment for manic or mixed episodes, as well as an adjunct to valproate or lithium for manic/mixed episodes based on bridging strategy allowed by the Food and Drug Administration.
Relevance to Patient Care and Clinical Practice:
The combination of olanzapine and samidorphan demonstrated efficacy for the treatment of schizophrenia with a dosage range of 5 to 20 mg OLZ to a 10-mg fixed dose of samidorphan. Advantages of this drug combination include once-daily dosing, favorable tolerability, and most importantly, mitigation of weight gain, which may encourage adherence, when compared with OLZ alone.
Conclusion:
The new combination treatment of OLZ/SAM is a unique antipsychotic formulation to provide the recognized efficacious treatment of OLZ, while mitigating the weight gain and possibly the weight-related adverse effects secondary to OLZ monotherapy.