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

Chronic kidney disease and physiologically based pharmacokinetic modeling: a critical review of existing models

INTRODUCTION

Physiologically based pharmacokinetic (PBPK) modeling is a paradigm shift in this era for determining the exposure of drugs in pediatrics, geriatrics, and patients with chronic diseases where clinical trials are difficult to conduct.

AREAS COVERED

This review has collated data regarding published PBPK models on chronic kidney disease (CKD), including the drug and system-specific input model parameters and model evaluation criteria. Four databases were used from 13th June 2023 to 10th July 2023 for identifying the relevant studies that met the inclusion/exclusion criteria. Alterations in plasma protein (albumin/alpha-1 acid glycoprotein), gastric emptying time, hematocrit, small intestinal transit time, the abundance of cytochrome (CYP) 450 enzymes, glomerular filtration rate, and physicochemical parameters for different drugs were explicitly elaborated from earlier reported studies. Moreover, model evaluation depicted that models in CKD for most of the included drugs were within the allowed two-fold error range.

EXPERT OPINION

This review will provide insights for researchers on applying PBPK models in managing patients with different levels of CKD to prevent undesirable side effects and increase the effectiveness of drug therapy.

An update on recently approved long-acting injectable second-generation antipsychotics: Knowns and unknowns regarding their use

There are now 9 available FDA-approved second-generation long-acting injectable antipsychotics including aripiprazole (3), olanzapine (1), paliperidone (3), and risperidone (2). These high-cost medications are commonly used with the goal of improving adherence and patient outcomes. With almost 2 decades of use, key aspects have been well studied, including population pharmacokinetics, CYP interactions and various clinical and economic outcomes. However, there are still unknowns with these medications. Issues including adherence, transition from oral antipsychotics, renal dosing, pharmacogenomics, and managing missed doses will be addressed in the context of 4 patient cases.

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.

Prediction of Janagliflozin Pharmacokinetics in Type 2 Diabetes Mellitus Patients with Liver Cirrhosis or Renal Impairment Using a Physiologically Based Pharmacokinetic Model

Janagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor for type 2 diabetes mellitus (T2DM). The janagliflozin pharmacokinetics (PK) in T2DM patients with cirrhosis or renal impairment (RI) are unknown. To predict the janagliflozin PK in these patients, we constructed a physiologically based PK (PBPK) model that predicted the janagliflozin PK in normal animals. The model was extrapolated to healthy humans and optimized with the measured data. A PBPK model for T2DM patients was developed and optimized with the measured data. Based on the physiological alterations in cirrhosis or RI patients, the T2DM model was applied to predict the janagliflozin PK in these patients. Results were validated using fold error values. The predicted AUC values were 21880, 24881, 26996, and 28419 ng/ml·h in T2DM patients with no cirrhosis, Child-Pugh-A, B, and C, respectively, and those in T2DM patients with RI-mild, RI-moderate, and RI-severe were 21810, 21840, and 22845 ng/ml·h, respectively. Janagliflozin exposure increased with increasing cirrhosis severity, whereas it remained stable regardless of the RI severity. The PBPK model predicted the janagliflozin PK in patients with T2DM and liver cirrhosis or RI. Dose adjustment is less critical for these patients. Risk benefit assessment in janagliflozin dosing for T2DM patients with liver disease is recommended.