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

The purpose of these extensive non-clinical studies was to assess pharmacokinetics and dispositional properties of sunitinib and its primary active metabolite (SU12662). 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. 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. Sunitinib exhibited advantageous pharmacokinetic and dispositional properties in non-clinical species, translating into favorable properties in humans.