Open AccessNonlinear Population Pharmacokinetics of Sirolimus in Patients With Advanced Cancer
Author(s) -
Wu K,
Cohen EEW,
House LK,
Ramírez J,
Zhang W,
Ratain MJ,
Bies RR
Publication year - 2012
Publication title -
cpt: pharmacometrics and systems pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.53
H-Index - 37
ISSN - 2163-8306
DOI - 10.1038/psp.2012.18
Subject(s) - nonmem , sirolimus , pharmacokinetics , medicine , population , population pharmacokinetics , pharmacology , covariate , mathematics , statistics , environmental health
Sirolimus, the prototypical inhibitor of the mammalian target of rapamycin, has substantial antitumor activity. In this study, sirolimus showed nonlinear pharmacokinetic characteristics over a wide dose range (from 1 to 60 mg/week). The objective of this study was to develop a population pharmacokinetic (PopPK) model to describe the nonlinearity of sirolimus. Whole blood concentration data, obtained from four phase I clinical trials, were analyzed using a nonlinear mixed‐effects modeling (NONMEM) approach. The influence of potential covariates was evaluated. Model robustness was assessed using nonparametric bootstrap and visual predictive check approaches. The data were well described by a two‐compartment model incorporating a saturable Michaelis–Menten kinetic absorption process. A covariate analysis identified hematocrit as influencing the oral clearance of sirolimus. The visual predictive check indicated that the final pharmacokinetic model adequately predicted observed concentrations. The pharmacokinetics of sirolimus, based on whole blood concentrations, appears to be nonlinear due to saturable absorption. CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e17; doi: 10.1038/psp.2012.18 ; advance online publication 5 December 2012