A Commentary on the Efficacy of Olanzapine for the Treatment of Schizophrenia: The Past, Present, and Future

Olanzapine is a second-generation atypical antipsychotic with proven efficacy for the treatment of schizophrenia. Approved in 1996, olanzapine is one of the most studied antipsychotics, resulting in a considerable amount of clinical data across diverse patient populations. Despite the fact that olanzapine is associated with a known risk of metabolic side effects, including weight gain, many clinicians continue to prescribe olanzapine for the treatment of schizophrenia with the expectation of additional therapeutic antipsychotic efficacy relative to other first-line atypical antipsychotics. The goal of this narrative is to revisit the role of oral olanzapine in the management of patients with schizophrenia, including those with recently diagnosed schizophrenia ( first-episode ), those with an established schizophrenia diagnosis who experience acute exacerbations, those receiving long-term antipsychotic treatment as a maintenance intervention, and those with suboptimal response to antipsychotic treatment, including treatment resistance. Collectively, data from published literature support the favorable efficacy of olanzapine compared with other first- and second-generation antipsychotics, including lower rates of treatment discontinuation and clinically meaningful improvements in the symptoms of schizophrenia. The development of antipsychotic medications with the favorable efficacy of olanzapine, but with reduced weight gain, could address a major unmet need in the treatment of schizophrenia

Opioid Antagonism Mitigates Antipsychotic-Associated Weight Gain: Focus on Olanzapine

BACKGROUND: The endogenous opioid system affects metabolism, including weight regulation. Evidence from preclinical and clinical studies provides a rationale for targeting this system to mitigate weight-related side effects of antipsychotics. This review describes the role of the opioid system in regulating weight and metabolism, examines the effects of opioid receptor antagonism on those functions, and explores the use of opioid antagonists to mitigate antipsychotic-associated weight gain and/or metabolic effects. METHODS: A PubMed literature search was conducted to identify representative opioid antagonists and associated preclinical and clinical studies examining their potential for the regulation of weight and metabolism. RESULTS: The mu opioid receptor (MOR), delta opioid receptor (DOR), and kappa opioid receptor (KOR) types have overlapping but distinct patterns of central and peripheral expression, and each contributes to the regulation of body weight and metabolism. Three representative opioid antagonists (eg, naltrexone, samidorphan, and LY255582) were identified for illustration. These opioid antagonists differed in their receptor binding and pharmacokinetic profiles, including oral bioavailability, systemic clearance, and half-life, and were associated with varying effects on food intake, energy utilization, and metabolic dysregulation. CONCLUSIONS: Preclinical and clinical data suggest that antagonism of the endogenous opioid system is a mechanism to address antipsychotic-associated weight gain and metabolic dysregulation. However, evidence suggests that the differing roles of MOR, DOR, and KOR in metabolism, together with the differences in receptor binding, pharmacokinetic, and functional activity profiles of the opioid receptor antagonists discussed in this review, likely contribute to their differential pharmacodynamic effects and clinical outcomes observed regarding antipsychotic-associated weight gain

An Evidence-Based Review of OLZ/SAM for Treatment of Adults with Schizophrenia or Bipolar I Disorder

Olanzapine effectively treats schizophrenia and bipolar I disorder (BD-I); however, its use is limited by the risk of significant weight gain and metabolic effects. OLZ/SAM, a combination of olanzapine and samidorphan, was recently approved in the United States for the treatment of adults with schizophrenia or BD-I. OLZ/SAM provides the efficacy of olanzapine while mitigating olanzapine-associated weight gain through opioid-receptor blockade. Here, we summarize OLZ/SAM clinical data characterizing pharmacokinetics, antipsychotic efficacy, weight mitigation efficacy, safety, and long-term treatment effects. In an acute exacerbation of schizophrenia, OLZ/SAM and olanzapine provided similar symptom improvements versus placebo at week 4. In stable outpatients with schizophrenia, OLZ/SAM treatment resulted in significantly less weight gain, reducing the risk for clinically significant weight gain and waist circumference increases of ≥5 cm by half, compared with olanzapine at week 24. Based on open-label extension studies, OLZ/SAM is safe and well tolerated for up to 3.5 years of treatment, while maintaining schizophrenia symptom control and stabilizing weight. The olanzapine component of OLZ/SAM was bioequivalent to branded olanzapine (Zyprexa); adjunctive OLZ/SAM had no clinically significant effects on lithium or valproate pharmacokinetics. Additionally, OLZ/SAM had no clinically relevant effect on electrocardiogram parameters in a dedicated thorough QT study. Overall, safety and tolerability findings from clinical studies with OLZ/SAM indicate a similar safety profile to that of olanzapine, with the exception of less weight gain. As OLZ/SAM contains the opioid antagonist samidorphan, it is contraindicated in patients using opioids and in those undergoing acute opioid withdrawal. Clinical trial results from more than 1600 subjects support the use of OLZ/SAM as a new treatment option for patients with schizophrenia or BD-I

Opioid Antagonism as a Target for Mitigation of Antipsychotic-Associated Weight Gain

Background Mechanisms underlying antipsychotic-associated weight gain are not well understood. The central and peripheral endogenous opioid system plays a role in weight and metabolic regulation, providing a rationale for targeting this system to attenuate antipsychotic-associated weight-related side effects that may impact treatment outcomes. Methods PubMed literature searches using the terms “opioid,” “opioid receptors,” “opioid antagonists,” “antipsychotic,” and “olanzapine” in combination with terms “weight” and “metabolism” were conducted to elucidate the role of the opioid system in the regulation of weight and metabolism, as well as potential for opioid antagonists to mitigate these effects. Results Nonclinical models provide evidence that activity at mu, delta, and kappa opioid receptors (MOR, DOR, KOR) mediate aspects of glucose and insulin regulation. Opioid antagonism has been associated with attenuated food consumption, with reduced fat accumulation, and with preventing insulin resistance in rats and nonhuman primates, an effect hypothesized to be mediated through MOR and DOR antagonism. In humans, opioid receptor agonism is associated with increased fat intake. A new treatment option that combines olanzapine, an antipsychotic associated with weight gain, with the opioid receptor antagonist samidorphan (OLZ/SAM) mitigated olanzapine-associated weight gain in healthy volunteers and mitigated olanzapine-associated weight gain and increases in waist circumference in patients with schizophrenia. Conclusions Opioid receptor blockade from samidorphan (in OLZ/SAM) mitigated olanzapine-associated weight gain and may provide additional benefits on other metabolic sequelae. Nonclinical and human data suggest that antagonism of the endogenous opioid system is a potential mechanism to address antipsychotic-associated weight gain and metabolic dysregulation

A Combination of Olanzapine and Samidorphan in Adults With Bipolar I Disorder and Schizophrenia: Overview of Clinical Data

Objectives Olanzapine effectively treats schizophrenia and bipolar I disorder (BD-I); however, its use is hindered by significant weight gain. A combination of olanzapine and samidorphan (OLZ/SAM) is in development to provide the efficacy of olanzapine while mitigating olanzapine-associated weight gain through opioid-receptor blockade. Here, we summarize OLZ/SAM clinical data. Methods The OLZ/SAM development program consists of 18 phase 1–3 clinical studies evaluating antipsychotic and weight mitigation efficacy of OLZ/SAM, along with pharmacokinetics, safety, and tolerability. Safety evaluation also included metabolic laboratory assessments. Results OLZ/SAM significantly improved psychotic symptoms (measured by Positive and Negative Syndrome Scale); improvements were similar to that observed with olanzapine vs placebo. OLZ/SAM resulted in significantly less weight gain than olanzapine. Additionally, 2 long-term phase 3 extension studies confirmed the durability of antipsychotic effect, as well as stabilization of weight and metabolic parameters in those continuing treatment. Supporting the potential use of OLZ/SAM in BD-I, OLZ/SAM or olanzapine resulted in bioequivalent olanzapine plasma concentrations, and OLZ/SAM did not affect lithium or valproate pharmacokinetics. OLZ/SAM treatment had no clinically relevant effects on ECG parameters (including QTc interval). OLZ/SAM and olanzapine safety were similar, except for reduced weight gain with OLZ/SAM; no additional safety risks were identified. Conclusion Data across 18 OLZ/SAM studies in \u3e1600 subjects support an antipsychotic efficacy and safety profile for OLZ/SAM that is similar to olanzapine, with significantly less weight gain than olanzapine. OLZ/SAM is a potential new treatment for schizophrenia and BD-I patients needing efficacious long-term treatment with reduced risk of weight gain