Single- and multiple-dose disposition kinetics of sunitinib malate, a multitargeted receptor tyrosine kinase inhibitor: comparative plasma kinetics in non-clinical species.

Purpose: The purpose of these extensive non-clinical studies was to assess pharmacokinetics and dispositional properties of sunitinib and its primary active metabolite (SU12662).

Methods: Sunitinib was administered in single and repeat oral doses in mice, rats, and monkeys. Assessments were made using liquid-chromatography-tandem mass spectrometric methods, radioactive assays, and quantitative whole body autoradiography.

Results: Sunitinib was readily absorbed with good oral bioavailability and linear kinetics at clinically-relevant doses. SU12662 plasma levels were less than those of sunitinib in mice and monkeys, but greater in rats. Sunitinib was extensively distributed with moderate-to-high systemic clearance and eliminated primarily into feces. Single- and repeat-dosing kinetics were similar. A prolonged half-life allowed once-daily dosing, enabling adequate systemic exposure with limited-to-moderate accumulation. In multiple-dose studies with cyclic dosing, drug plasma concentrations cleared from one cycle to the next.

Conclusions: Sunitinib exhibited advantageous pharmacokinetic and dispositional properties in non-clinical species, translating into favorable properties in humans.