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

Population pharmacokinetics of olanzapine in pediatric patients with psychiatric disorders

OBJECTIVE

To develop and validate a population pharmacokinetic (PPK) model of oral olanzapine in pediatric Chinese patients in order to individualize therapy in this population.

METHODS

A total of 897 serum concentrations from 269 pediatric patients taking oral olanzapine (ages 8-17 years) were collected. Demographic parameters, biological characteristics and concomitant medications were investigated as covariates. The data were analyzed using a nonlinear mixed-effects modeling approach. Bootstrapping (1000 runs), normalized prediction distribution error (NPDE), and external validation of 62 patients were employed. Simulations were performed to explore the individualized dosing regimens in various situations.

RESULTS

The one-compartment model with first-order absorption and elimination had an apparent clearance (CL/F) of 10.38 L/h, a distribution volume (V/F) of 9.41 L/kg and an absorption rate constant (Ka) fixed at 0.3 h-1. The equation was CL∕F (L∕h) = 10.38 × (body weight∕60)0.25 ×1.33 (if male) × 0.71 (if co-occurrence of infection) × 0.51 (if co-therapy with fluvoxamine) × 1.27 (if co-therapy with sertraline) × 1.43 (if co-therapy with valproate). The final model had satisfactory stability, robustness, and predictive ability. The results from a simulation suggested the oral olanzapine doses required for male and female pediatric patients weighing between 40 and 60 kg without co-medication were 10-15 mg/day and 7.5-10 mg/day, respectively, and dosage adjustments should be based on sex and body weight; and co-administrated with valproate, sertraline, or fluvoxamine.

CONCLUSION

This model may help individualize optimum dosing of oral olanzapine for pediatric patients.

Effects of Aripiprazole on Olanzapine Population Pharmacokinetics and Initial Dosage Optimization in Schizophrenia Patients

Objective

Olanzapine has already been used to treat schizophrenia patients; however, the initial dosage recommendation when multiple drugs are used in combination, remains unclear. The purpose of this study was to explore the drug-drug interaction (DDI) of multiple drugs combined with olanzapine and to recommend the optimal administration of olanzapine in schizophrenia patients.

Methods

In this study, we obtained olanzapine concentrations from therapeutic drug monitoring (TDM) database. In addition, related medical information, such as physiological, biochemical indexes, and concomitant drugs was acquired using medical log. Sixty-five schizophrenia patients were enrollmented for analysis using population pharmacokinetic model by means of nonlinear mixed effect (NONMEM).

Results

Weight and combined use of aripiprazole significantly affected olanzapine clearance. Without aripiprazole, for once-daily olanzapine administration dosages, 0.6, 0.5 mg/kg/day were recommended for 40-70, and 70-100 kg schizophrenia patients, respectively; for twice-daily olanzapine administration dosages, 0.6, 0.5 mg/kg/day were recommended for 40-60, and 60-100 kg schizophrenia patients, respectively. With aripiprazole, for once-daily olanzapine administration dosages, 0.4, 0.3 mg/kg/day were recommended for 40-53, and 53-100 kg schizophrenia patients, respectively; for twice-daily olanzapine administration dosages, 0.4 mg/kg/day was recommended for 40-100 kg schizophrenia patients, respectively.

Conclusion

Aripiprazole significantly affected olanzapine clearance, and when schizophrenia patients use aripiprazole, the olanzapine dosages need adjust. Meanwhile, we firstly recommended the optimal initial dosages of olanzapine in schizophrenia patients.

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.

Olanzapine/Samidorphan: A New Combination Treatment for Schizophrenia and Bipolar I Disorder Intended to Reduce Weight Gain

Olanzapine is a second-generation antipsychotic with established efficacy in several psychiatric disease states, but its use is limited because of weight gain and metabolic side effects. Samidorphan is a novel opioid antagonist that binds to mu-opioid, kappa-opioid, and delta-opioid receptors and is hypothesized to reduce cravings for high-calorie foods thus attenuating antipsychotic-induced weight gain. The combination product olanzapine/samidorphan was approved by the US Food and Drug Administration in June 2021 for the treatment of schizophrenia and bipolar I disorder; this article reviews the pharmacological properties of oral olanzapine/samidorphan and its clinical efficacy and tolerability with a focus on mitigation of olanzapine-induced weight gain in these patient populations. In clinical trials, the combination of olanzapine/samidorphan was associated with significantly less weight gain and smaller increases in waist circumference as compared with olanzapine monotherapy. Olanzapine/samidorphan demonstrated similar efficacy as olanzapine monotherapy and was well tolerated. Weight gain and metabolic side effects associated with olanzapine monotherapy can result in tolerability issues and potentially medication nonadherence. Olanzapine/samidorphan is an effective treatment for schizophrenia and bipolar I disorder with less weight gain than olanzapine monotherapy.

Utilization of Polymeric Micelles as a Lucrative Platform for Efficient Brain Deposition of Olanzapine as an Antischizophrenic Drug via Intranasal Delivery

Schizophrenia is a mental disorder characterized by alterations in cognition, behavior and emotions. Oral olanzapine (OZ) administration is extensively metabolized (~up to 40% of the administrated dose). In addition, OZ is a P-glycoproteins substrate that impairs the blood–brain barrier (BBB) permeability. To direct OZ to the brain and to minimize its systemic side effects, the nasal pathway is recommended. OZ-loaded polymeric micelles nano-carriers were developed using suitable biodegradable excipients. The developed micelles were physicochemically investigated to assess their appropriateness for intranasal delivery and the potential of these carriers for OZ brain targeting. The selected formula will be examined in vivo for improving the anti-schizophrenic effects on a schizophrenia rat model. The binary mixture of P123/P407 has a low CMC (0.001326% w/v), which helps in maintaining the formed micelles’ stability upon dilution. The combination effect of P123, P407 and TPGS led to a decrease in micelle size, ranging between 37.5–47.55 nm and an increase in the EE% (ranging between 68.22–86.84%). The selected OZ–PM shows great stability expressed by a suitable negative charge zeta potential value (−15.11 ± 1.35 mV) and scattered non-aggregated spherical particles with a particle size range of 30–40 nm. OZ–PM maintains sustained drug release at the application site with no nasal cytotoxicity. In vivo administration of the selected OZ–PM formula reveals improved CNS targeting and anti-schizophrenia-related deficits after OZ nasal administration. Therefore, OZ–PM provided safe direct nose-to-brain transport of OZ after nasal administration with an efficient anti-schizophrenic effect.