Modeling and Simulation Analysis of Aprepitant Pharmacokinetics in Pediatric Patients With Postoperative or Chemotherapy-Induced Nausea and Vomiting

OBJECTIVES: Aprepitant is effective for the prevention of chemotherapy-induced or postoperative nausea and vomiting (CINV/PONV). The aim of this study was to develop a population pharmacokinetic (PK) model of aprepitant in pediatric patients and to support dosing recommendations for oral aprepitant in pediatric patients at risk of CINV. METHODS: A population PK model was constructed based on data from 3 clinical studies in which children (6 months to 12 years) and adolescents (12-19 years) were treated with a 3-day regimen of oral aprepitant (capsules or suspension), with or without intravenous fosaprepitant on day 1 (CINV), or a single dose of oral aprepitant (capsules or suspension; PONV). Nonlinear mixed-effects modeling was used for model development, and a stepwise covariate search determined factors influencing PK parameters. Simulations were performed to guide final dosing strategies of aprepitant in pediatric patients. RESULTS: The analysis included 1326 aprepitant plasma concentrations from 147 patients. Aprepitant PK was described by a 2-compartment model with linear elimination and first-order absorption, with allometric scaling for central and peripheral clearance and volume using body weight, and a cytochrome P450 3A4 maturation component for the effect of ontogeny on systemic clearance. Simulations established that application of a weight-based (for those <12 years) and fixed-dose (for those 12-17 years) dosing regimen results in comparable exposures to those observed in adults. CONCLUSIONS: The developed population PK model adequately described aprepitant PK across a broad pediatric population, justifying fixed (adult) dosing for adolescents and weight-based dosing of oral aprepitant for children.