Population-based analysis of methadone distribution and metabolism using an age-dependent physiologically based pharmacokinetic model. J Pharmacokinet Pharmacodyn 2006 Aug;33(4):485-518
Date
06/08/2006Pubmed ID
16758333DOI
10.1007/s10928-006-9018-0Scopus ID
2-s2.0-33745621573 (requires institutional sign-in at Scopus site) 82 CitationsAbstract
Limited pharmacokinetic (PK) and pharmacodynamic (PD) data are available to use in methadone dosing recommendations in pediatric patients for either opioid abstinence or analgesia. Considering the extreme inter-individual variability of absorption and metabolism of methadone, population-based PK would be useful to provide insight into the relationship between dose, blood concentrations, and clinical effects of methadone. To address this need, an age-dependent physiologically based pharmacokinetic (PBPK) model has been constructed to systematically study methadone metabolism and PK. The model will facilitate the design of cost-effective studies that will evaluate methadone PK and PD relationships, and may be useful to guide methadone dosing in children. The PBPK model, which includes whole-body multi-organ distribution, plasma protein binding, metabolism, and clearance, is parameterized based on a database of pediatric PK parameters and data collected from clinical experiments. The model is further tailored and verified based on PK data from individual adults, then scaled appropriately to apply to children aged 0-24 months. Based on measured variability in CYP3A enzyme expression levels and plasma orosomucoid (ORM2) concentrations, a Monte-Carlo-based simulation of methadone kinetics in a pediatric population was performed. The simulation predicts extreme variability in plasma concentrations and clearance kinetics for methadone in the pediatric population, based on standard dosing protocols. In addition, it is shown that when doses are designed for individuals based on prior protein expression information, inter-individual variability in methadone kinetics may be greatly reduced.
Author List
Yang F, Tong X, McCarver DG, Hines RN, Beard DAMESH terms used to index this publication - Major topics in bold
AdultAge Factors
Analgesics, Opioid
Area Under Curve
Biological Availability
Child, Preschool
Computer Simulation
Humans
Hydrogen-Ion Concentration
Infant
Infant, Newborn
Male
Methadone
Middle Aged
Models, Biological
Monte Carlo Method
Protein Binding
Regression Analysis
Stereoisomerism
Tissue Distribution
