Bioequivalence of Olanzapine Given in Combination With Samidorphan as a Bilayer Tablet (ALKS 3831) Compared With Olanzapine-Alone Tablets: Results From a Randomized, Crossover Relative Bioavailability Study

Changes in hypothalamic mu-opioid receptor expression following acute olanzapine treatment in female rats: Implications for feeding behavior

Advances have been made in recent years in using opioid receptor antagonists as an adjunct therapy to psychotropic medication to reduce debilitating weight gain and metabolic adverse effects associated with in particular second generation antipsychotics. However, it is unknown whether second generation antipsychotics produce a change in opioid receptor expression in the brain. The present study investigated early changes in opioid receptor expression in the female rat hypothalamus, a master controller of hunger and metabolic regulation, after acute treatment with olanzapine, a commonly used second generation antipsychotic. Using quantitative spatial in situ hybridization and receptor autoradiography, expression levels of the three opioid receptors; kappa, mu and delta, were determined at mRNA and protein level, respectively, in the five hypothalamic areas: paraventricular nucleus, arcuate nucleus, ventromedial nucleus, dorsomedial nucleus and lateral hypothalamus. After 48 h of olanzapine treatment at clinically relevant plasma concentration weight gain and food intake changes, and increased plasma glucose were observed in female rats. Olanzapine treatment also led to a significant increase in mu opioid receptor availability in the arcuate nucleus, which contains both satiety and hunger controlling neurons. No other areas showed any opioid receptor expressional changes with olanzapine treatment on neither at mRNA nor protein level. Technical difficulties made it impossible to analyze mRNA levels in the lateral hypothalamus and overall binding of delta opioid receptors. Thus, the present study provided insights in to how olanzapine at clinically relevant plasma levels already at an early stage modulated the opioid system in the hypothalamus.

Combining samidorphan with olanzapine to mitigate weight gain as a side effect in schizophrenia treatment

Purpose

This article analyzes clinical trials that provide evidence for the positive effects of using samidorphan to mitigate undesirable weight gain in patients diagnosed with schizophrenia who are undergoing treatment with olanzapine.

Views

Weight gain is a prevalent and problematic side effect of antipsychotic drug therapy, particularly in patients with schizophrenia. To address this issue, extensive research is being conducted to explore new drug therapies that can effectively counteract psychotic symptoms while minimizing the occurrence of unwanted side effects. One promising approach involves the addition of weight-loss substances to existing medications. Studies have indicated that opioid receptor antagonists, such as samidorphan, have the potential to facilitate weight loss. Consequently, a novel therapy combining samidorphan and olanzapine has been developed and is discussed in detail in this article.

Conclusions

The combination of samidorphan and olanzapine has demonstrated its ability to effectively reduce weight gain in patients with schizophrenia, without compromising the drug's primary function of alleviating psychotic symptoms. Moreover, the inclusion of samidorphan in the treatment regimen may contribute to a lower risk of cardiovascular events, though it is worth noting that it could also lead to an increase in digestive side effects. Despite this potential drawback, the introduction of this innovative therapy represents a significant advancement in the management of obesity among individuals with schizophrenia.

Spatial quantification of single cell mRNA and ligand binding of the kappa opioid receptor in the rat hypothalamus

Detailed quantification of brain tissue provides a deeper understanding of changes in expression and function. We have created a pipeline to study the detailed expression patterns of the kappa opioid receptor in the rat hypothalamus using high resolution fluorescence microscopy and receptor autoradiography. The workflow involved structured serial sampling of rat hypothalamic nuclei, in situ detection of mRNA and receptor expression, and advanced image analysis. Our results demonstrate how maintaining spatial information can lead to increased understanding of RNA and protein expression. In addition, we show the detailed expression patterns of the kappa opioid receptor in the rat hypothalamus.

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.

Samidorphan for the treatment of weight gain associated with olanzapine in patients with schizophrenia and bipolar disorder

INTRODUCTION

Olanzapine (OLZ) is one of the most effective antipsychotic agents, however, its clinical utility has been limited by weight gain. Samidorphan (SAM) is aμ-opioid receptor antagonist and it can reduce the weight gain associated with OLZ. A combination of OLZ and SAM (OLZ/SAM) has been developed to provide the antipsychotic efficacy of OLZ, while mitigating OLZ-associated weight gain.

AREAS COVERED

A comprehensive literature search was conducted in PubMed. Key search terms included SAM and weight gain associated with OLZ. The pharmacological action, clinical efficacy, and safety of SAM were reviewed.

EXPERT OPINION

OLZ can lead to weight gain. SAM is a new drug that acts as an opioid receptor antagonist that can decrease weight gain. SAM mitigates OLZ-associated weight gain while preserving the antipsychotic efficacy of OLZ. Clinical trials have confirmed that OLZ/SAM significantly improved psychotic symptoms, and resulted in significantly less weight gain than OLZ. OLZ/SAM was well tolerated. Therefore, it is a potential new treatment option for schizophrenia.

Physiologically Based Pharmacokinetic Modeling in Pregnant Women Suggests Minor Decrease in Maternal Exposure to Olanzapine

Pregnancy is accompanied by significant physiological changes that might affect the in vivo drug disposition. Olanzapine is prescribed to pregnant women with schizophrenia, while its pharmacokinetics during pregnancy remains unclear. This study aimed to develop a physiologically based pharmacokinetic (PBPK) model of olanzapine in the pregnant population. With the contributions of each clearance pathway determined beforehand, a full PBPK model was developed and validated in the non-pregnant population. This model was then extrapolated to predict steady-state pharmacokinetics in the three trimesters of pregnancy by introducing gestation-related alterations. The model adequately simulated the reported time-concentration curves. The geometric mean fold error of Cmax and AUC was 1.14 and 1.09, respectively. The model predicted that under 10 mg daily dose, the systematic exposure of olanzapine had minor changes (less than 28%) throughout pregnancy. We proposed that the reduction in cytochrome P4501A2 activity is counteracted by the induction of other enzymes, especially glucuronyltransferase1A4. In conclusion, the PBPK model simulations suggest that, at least at the tested stages of pregnancy, dose adjustment of olanzapine can hardly be recommended for pregnant women if effective treatment was achieved before the onset of pregnancy and if fetal toxicity can be ruled out.

New Antipsychotic Medications in the Last Decade

PURPOSE OF REVIEW

Over the last ten years, the treatment of psychosis has seen a near explosion of creative development in both novel agents and new delivery modalities. The current review summarizes these developments over the past decade (2011-2020). We performed a systematic review utilizing PubMed and PsychInfo with the aim of identifying all the RCT and related analyses in adults with psychosis (schizophrenia and mania).

RECENT FINDINGS

We identified 11 significant developments: the introduction of new antipsychotics cariprazine, brexpiprazole, lumateperone, and pimavanserin; introduction of new delivery methods: subcutaneous long-acting risperidone, aripiprazole lauroxil, transdermal asenapine, and inhaled loxapine; and the introduction of new approaches such as olanzapine/samidorphan for olanzapine-associated weight gain, examination of the TAAR1 agonist SEP 363,856 as a test of concept, and the combination of Xanomeline/Trospium, an M₁ and M₄ muscarinic receptor agonist in conjunction with a peripheral anticholinergic. Last decade has seen a tremendous development in second-generation antipsychotics which provides unprecedented treatment options for clinicians in treating psychosis.

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.

Olanzapine/Samidorphan: First Approval

Samidorphan, which was developed by Alkermes, is an opioid receptor antagonist that has been co-formulated with olanzapine into a single-dose oral tablet to mitigate the risk of weight gain while providing the therapeutic effect of olanzapine. Olanzapine/samidorphan (LYBALVI^™) was recently approved in the USA for the treatment of schizophrenia and bipolar I disorder. This article summarizes the milestones in the development of samidorphan leading to this first approval of olanzapine/samidorphan.

Using physiologically-based pharmacokinetic modeling for predicting the effects of hepatic impairment on the pharmacokinetics of olanzapine and samidorphan given as a combination tablet

A combination of olanzapine and samidorphan (OLZ/SAM) was recently approved by the US Food and Drug Administration for treatment of patients with schizophrenia or bipolar I disorder. The effects of moderate hepatic impairment on the pharmacokinetics (PKs) of olanzapine and samidorphan after a single dose of OLZ/SAM were characterized in a clinical study. Physiologically-based pharmacokinetic (PBPK) modeling was used to extend the clinical findings to predict the effects of varying degrees of hepatic impairment on the PKs of olanzapine and samidorphan. A previously developed PBPK model for OLZ/SAM was refined to recover the observed pharmacokinetic differences between individuals with moderate hepatic impairment and healthy controls. The optimized model was applied to predict changes in olanzapine and samidorphan PKs after multiple once-daily doses of OLZ/SAM in subjects with mild, moderate, and severe hepatic impairment relative to healthy controls. Modifications to model parameters, including absorption rate constant and fraction unbound to plasma protein, were made to recover the observed change in the PKs of olanzapine and samidorphan in individuals with moderate hepatic impairment. In applying the optimized model, mild, moderate, and severe hepatic impairment were predicted to increase steady-state total systemic exposures by 1.1-, 1.5-, and 1.6-fold, respectively, for olanzapine, and by 1.2-, 1.9-, and 2.3-fold, respectively, for samidorphan. PBPK modeling allowed for prediction of untested clinical scenarios of varying degrees of hepatic impairment in lieu of additional clinical studies.

Population Pharmacokinetics of Olanzapine and Samidorphan When Administered in Combination in Healthy Subjects and Patients With Schizophrenia

A combination of olanzapine and samidorphan was recently approved by the US Food and Drug Administration for the treatment of patients with schizophrenia or bipolar I disorder. Population pharmacokinetic models for olanzapine and samidorphan were developed using data from 11 clinical studies in healthy subjects or patients with schizophrenia. A 2‐compartment disposition model with first‐order absorption and elimination and a lag time for absorption adequately described concentration‐time profiles of both olanzapine and samidorphan. Age, sex, race, smoking status, and body weight were identified as covariates that impacted the pharmacokinetics of olanzapine. A moderate effect of body weight on samidorphan pharmacokinetics was identified by the model but was not considered clinically meaningful. The effects of food, hepatic or renal impairment, and coadministration with rifampin on the pharmacokinetics of olanzapine and samidorphan, as estimated by the population pharmacokinetic analysis, were consistent with findings from dedicated clinical studies designed to evaluate these specific covariates of interest. Food intake did not have a clinically relevant effect on the pharmacokinetics of olanzapine or samidorphan. Consistent with the known metabolic pathways for olanzapine (primarily via uridine 5′‐diphospho‐glucuronosyltransferase–mediated direct glucuronidation and cytochrome P450 [CYP]‐mediated oxidation) and for samidorphan (predominantly mediated by CYP3A4), coadministration of olanzapine and samidorphan with rifampin, a strong inducer of CYP3A4 and an inducer of uridine 5′‐diphospho‐glucuronosyltransferase enzymes, significantly decreased the systemic exposure of both olanzapine and samidorphan. Severe renal impairment or moderate hepatic impairment resulted in a modest increase in olanzapine and samidorphan exposure.

How and when to treat the most common adverse effects of antipsychotics: Expert review from research to clinical practice

OBJECTIVE

As most treatment guidelines for antipsychotics focus on clinical efficacy, we will instead focus on adverse effects and how to manage them. In this review, we aim to provide an up-to-date clinical resource for providers who prescribe antipsychotics and have included here "what's new" and "what to do" for numerous antipsychotic-induced adverse effects.

METHODS

A review was performed of relevant literature, studies, randomized clinical trials, and systematic reviews. This information was combined with the clinical experience of the authors to formulate a practical guide for treating adverse effects of antipsychotics with an emphasis on metabolic and movement disorder adverse effects and brief mention of some others (sedation and sexual dysfunction).

CONCLUSIONS

Antipsychotics are an integral part of psychiatric care and are often prescribed lifelong. When choosing an antipsychotic, special consideration must be given to adverse effects which have an undeniable impact on quality of life and can often be the deciding factor in patients' medication compliance. While patients may respond well to one specific medication, they may still experience adverse effects that lead them to discontinue it or switch to a more tolerable but less effective option. However, strategies do exist for managing and treating adverse effects, especially metabolic and movement adverse effects, allowing better personalization of antipsychotic choice.

Application of Physiologically Based Pharmacokinetic Modeling to Predict the Effect of Renal Impairment on the Pharmacokinetics of Olanzapine and Samidorphan Given in Combination

BACKGROUND

A combination of the antipsychotic olanzapine and opioid receptor antagonist samidorphan (OLZ/SAM) is in development for the treatment of patients with schizophrenia or bipolar I disorder. The effect of severe renal impairment on the pharmacokinetics of olanzapine and samidorphan after a single oral dose of OLZ/SAM was evaluated in a clinical study. Complementary to the clinical findings, physiologically based pharmacokinetic modeling was used to assess the effects of varying degrees of renal impairment on the pharmacokinetics of olanzapine and samidorphan.

METHODS

A physiologically based pharmacokinetic model for OLZ/SAM was developed and validated by comparing model-simulated data with observed clinical data. The model was applied to predict changes in olanzapine and samidorphan pharmacokinetics after administration of OLZ/SAM in subjects with mild, moderate, and severe renal impairment relative to age-matched controls with normal renal function.

RESULTS

The model predicted 1.5- and 2.2-fold increases in olanzapine and samidorphan area under the plasma concentration-time curve (AUC), respectively, after a single dose of OLZ/SAM in subjects with severe renal impairment vs controls, which was consistent with results from the clinical study. Application of the model prediction indicated increases in steady-state olanzapine AUC of 1.2-, 1.5-, and 1.6-fold, and samidorphan AUC of 1.4-, 1.8-, and 2.2-fold, in subjects with mild, moderate, and severe renal impairment, respectively, relative to healthy controls.

CONCLUSIONS

Physiologically based pharmacokinetic modeling extended the findings from a clinical study in severe renal impairment to other untested clinical scenarios; these data could be of interest to clinicians treating patients with renal impairment.

Combination of olanzapine and samidorphan has no clinically relevant effects on ECG parameters, including the QTc interval: Results from a phase 1 QT/QTc study

BACKGROUND

OLZ/SAM is a combination of olanzapine, an atypical antipsychotic, and samidorphan, an opioid antagonist, and is in development for the treatment of schizophrenia and bipolar I disorder. OLZ/SAM is under development with the intent to provide the established antipsychotic efficacy of olanzapine while mitigating olanzapine-associated weight gain. This thorough QT study assessed the effects of therapeutic and supratherapeutic doses of OLZ/SAM on cardiac repolarization in patients with schizophrenia.

METHODS

In this randomized, double-blind, placebo- and positive (moxifloxacin)-controlled, parallel-group study, 100 patients aged 18 to 60 years with stable schizophrenia were randomized 3:2 to the active arm and control arm. Subjects in the active arm received a therapeutic dose of 10/10 mg (10 mg olanzapine/10 mg samidorphan) on days 2-4, 20/20 mg on days 5-8, and a supratherapeutic dose of 30/30 mg (1.5 times and 3 times the maximum recommended daily dose of olanzapine and samidorphan, respectively) on days 9-13, and moxifloxacin-matched placebo on days 1 and 14. Subjects in the control arm received a single oral dose of moxifloxacin 400 mg and moxifloxacin-matched placebo on days 1 and 14 in a nested crossover fashion, along with OLZ/SAM-matched placebo on days 2-13. Serial electrocardiograms (ECGs) and simultaneous plasma drug concentrations were determined pre- and post-dose. The effects of OLZ/SAM on heart rate and ECG parameters (QT interval with Fridericia's correction [QTcF], PR and QRS interval, and T-wave morphology) were evaluated, and the primary endpoint was change from baseline in QTcF (ΔQTcF). The relationship between drug concentration and ΔQTcF (C-QTc) was evaluated using a linear mixed-effects model. Safety monitoring included adverse events reporting and clinical laboratory assessments.

RESULTS

Based on primary analysis using C-QTc modeling, no clinically concerning QTc effect (ie, placebo-corrected ΔQTcF [ΔΔQTcF] ≥10 msec) was observed across the OLZ/SAM dose range tested (10/10 to 30/30 mg), up to olanzapine and samidorphan concentrations of approximately 110 and 160 ng/mL, respectively. The slope (90% confidence interval [CI]) of the C-QTc relationship was shallow and not significant for either olanzapine or samidorphan (0.03 [-0.01, 0.08] and 0.01 [-0.01, 0.04] msec per ng/mL, respectively). The predicted ΔΔQTcF (90% CI) was 2.33 (-2.72, 7.38) and 1.38 (-3.37, 6.12) msec at the observed geometric mean maximal concentration (C_max) of olanzapine (62.6 ng/mL) and samidorphan (75.1 ng/mL) on day 13, respectively. The study's assay sensitivity was confirmed by the C-QTc relationship of moxifloxacin. OLZ/SAM was well tolerated at all doses; adverse events occurring in >5% of subjects treated with OLZ/SAM were somnolence, weight increased, nausea, and dizziness.

CONCLUSIONS

This thorough QT study in patients with stable schizophrenia demonstrated that OLZ/SAM, in doses and plasma concentrations up to supratherapeutic levels, does not have a clinically relevant effect on ECG parameters, including QT/QTc prolongation.

Physiologically-Based Pharmacokinetic Modeling for Predicting Drug Interactions of a Combination of Olanzapine and Samidorphan

A combination of the antipsychotic olanzapine and the opioid receptor antagonist samidorphan (OLZ/SAM) is intended to provide the antipsychotic efficacy of olanzapine while mitigating olanzapine-associated weight gain. As cytochrome P450 (CYP) 1A2 and CYP3A4 are the major enzymes involved in metabolism of olanzapine and samidorphan, respectively, physiologically-based pharmacokinetic (PBPK) modeling was applied to predict any drug-drug interaction (DDI) potential between olanzapine and samidorphan or between OLZ/SAM and CYP3A4/CYP1A2 inhibitors/inducers. A PBPK model for OLZ/SAM was developed and validated by comparing model-simulated data with observed clinical study data. Based on model-based simulations, no DDI between olanzapine and samidorphan is expected when administered as OLZ/SAM. CYP3A4 inhibition is predicted to have a weak effect on samidorphan exposure and negligible effect on olanzapine exposure. CYP3A4 induction is predicted to reduce both samidorphan and olanzapine exposure. CYP1A2 inhibition or induction is predicted to increase or decrease, respectively, olanzapine exposure only.

Effect of hepatic and renal impairment on the pharmacokinetics of olanzapine and samidorphan given in combination as a bilayer tablet

Background

A combination of olanzapine and samidorphan (OLZ/SAM) is in development to provide the established antipsychotic efficacy of olanzapine while mitigating olanzapine-induced weight gain.

Methods

Two multicenter, open-label, parallel-cohort studies were performed to evaluate the effect of moderate hepatic impairment (Child-Pugh score 7–9 [class B]; study 1) and severe renal impairment (estimated glomerular filtration rate: 15–29 mL/min/1.73 m²; study 2) on the pharmacokinetics, safety, and tolerability of a single dose of OLZ/SAM 5/10 mg.

Results

There was a 1.67-fold increase in area under the plasma concentration-time curve from time 0 to infinity (AUC_0-∞) and a 2.17-fold increase in maximum plasma concentration (C_max) of olanzapine, and a 1.52-fold increase in AUC_0-∞ and a 1.63-fold increase in C_max of samidorphan, in subjects with moderate hepatic impairment compared with healthy control subjects. Compared with healthy control subjects, subjects with severe renal impairment had a 33% and 56% reduction in clearance, a 1.51- and 2.31-fold increase in AUC_0-∞, and a 1.32- and 1.37-fold increase in C_max of olanzapine and samidorphan, respectively.

Conclusion

OLZ/SAM 5/10 mg was generally well tolerated under the conditions of the studies, with a safety profile consistent with that observed in other clinical studies of OLZ/SAM.

A Review of Samidorphan: A Novel Opioid Antagonist

Opioid modulators have been explored as a treatment option for psychiatric disorders, but their use has been limited due to their abuse potential. Samidorphan (SAM), a μ-opioid receptor antagonist, has gained interest due to its favorable pharmacokinetic and pharmacodynamic profile. In this review article, six electronic databases including PubMed, PsycINFO, PsycARTICLES, Scopus, Web of Science, and CINAHL were searched to find relevant human studies with a focus on different clinical aspects of SAM. SAM was used in combination with buprenorphine (BUP) to counteract the abuse potential while still maintaining effectiveness in the treatment of depression. The BUP/SAM 2 mg/2mg combination improved depression in patients with major depressive disorder (MDD). SAM's ability to mitigate the weight gain associated with olanzapine (OLZ) has also been explored. Initial studies have shown promising results in some parameters of alcohol-use disorder, while no significant benefit in the treatment of binge-eating disorder has been reported. Somnolence and gastrointestinal side effects were the most commonly observed side effects of SAM.