Metabolism The calculated in vitro Ki values for all CYP isoforms tested (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4/ 5 AND CYP4A9/ 11) indicated that sunitinib and its primary active metabolite are unlikely to inhibit metabolism, to any clinically relevant extent, of drugs that may be metabolized by these enzymes.