[The antipsychotic drug aripiprazole (ABILIFY)]

Drug-drug interaction and initial dosage optimization of aripiprazole in patients with schizophrenia based on population pharmacokinetics

Background

The present study aimed to investigate the drug-drug interaction and initial dosage optimization of aripiprazole in patients with schizophrenia based on population pharmacokinetics.

Research design and methods

A total of 119 patients with schizophrenia treated with aripiprazole were included to build an aripiprazole population pharmacokinetic model using nonlinear mixed effects.

Results

The weight and concomitant medication of fluoxetine influenced aripiprazole clearance. Under the same weight, the aripiprazole clearance rates were 0.714:1 in patients with or without fluoxetine, respectively. In addition, without fluoxetine, for the once-daily aripiprazole regimen, dosages of 0.3 and 0.2 mg kg-1 day-1 were recommended for patients with schizophrenia weighing 40-95 and 95-120 kg, respectively, while for the twice-daily aripiprazole regimen, 0.3 mg kg-1 day-1 was recommended for those weighing 40-120 kg. With fluoxetine, for the once-daily aripiprazole regimen, a dosage of 0.2 mg kg-1 day-1 was recommended for patients with schizophrenia weighing 40-120 kg, while for the twice-daily aripiprazole regimen, 0.3 and 0.2 mg kg-1 day-1 were recommended for those weighing 40-60 and 60-120 kg, respectively.

Conclusion

This is the first investigation of the effects of fluoxetine on aripiprazole via drug-drug interaction. The optimal aripiprazole initial dosage is recommended in patients with schizophrenia.

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.

Differences in autonomic nervous system activity between long-acting injectable aripiprazole and oral aripiprazole in schizophrenia

BACKGROUND

Distinct oral atypical antipsychotics have different effects on autonomic nervous system (ANS) activity. Among them, oral aripiprazole has been linked to dysfunction of the ANS in schizophrenia. Long-acting injectable aripiprazole is a major treatment option for schizophrenia, but the effect of the aripiprazole formulation on ANS activity remains unclear. In this study, we compared ANS activity between oral aripiprazole and aripiprazole once-monthly (AOM) in schizophrenia.

METHODS

Of the 122 patients with schizophrenia who participated in this study, 72 received oral aripiprazole and 50 received AOM as monotherapy. We used power spectral analysis of heart rate variability to assess ANS activity.

RESULTS

Patients who received oral aripiprazole showed significantly diminished sympathetic nervous activity compared with those who received AOM. Multiple regression analysis revealed that the aripiprazole formulation significantly influenced sympathetic nervous activity.

CONCLUSION

Compared with oral aripiprazole, AOM appears to have fewer adverse effects, such as sympathetic nervous dysfunction.

Treatment Persistence Between Long-Acting Injectable Versus Orally Administered Aripiprazole Among Patients with Schizophrenia in a Real-World Clinical Setting in Japan

INTRODUCTION

Persistence with antipsychotic treatment is critical in managing patients with schizophrenia. To evaluate whether aripiprazole long-acting injection (aripiprazole once-monthly, AOM) can contribute to longer treatment persistence compared with daily orally administered aripiprazole (OA) in real-world clinical settings in Japan, treatment persistence in patients with schizophrenia was compared between patients treated with AOM and those with OA, using a claims database compiled by JMDC Inc., Tokyo, Japan.

METHODS

Data of patients with schizophrenia who newly initiated AOM or OA treatment between May 2015 and November 2017 were analyzed. The Cox proportional hazard model was used to estimate the hazard ratio (HR) for treatment discontinuation of AOM vs. OA treatment, adjusted for age, sex, chlorpromazine-equivalent dose of antipsychotics, and the number of psychiatric hospitalizations.

RESULTS

The analysis included 198 patients in the AOM group and 1240 patients in the OA group (mean age 38.4 ± 11.9 years and 39.3 ± 12.4 years, respectively). The AOM group was significantly less likely to discontinue treatment than the OA group (adjusted HR 0.54, 95% confidence interval [CI] 0.43-0.68). When using the tolerable patients extracted from the OA group (i.e., patients with at least two OA prescriptions; n = 983) vs. the whole AOM group, AOM users were again significantly less likely to discontinue treatment (adjusted HR 0.67, 95% CI 0.53-0.86).

CONCLUSION

AOM was associated with longer treatment persistence than OA in the antipsychotic treatment of patients with schizophrenia in real-world clinical settings in Japan, suggesting that the use of AOM may contribute to longer antipsychotic treatment.