CYP3A4 mediated in vitro metabolism of vinflunine in human liver microsomes

Abstract

To study the metabolism of vinflunine and the effects of selective cytochrome P-450 (CYP450) inhibitors on the metabolism of vinflunine in human liver microsomes. Individual selective CYP450 inhibitors were used to investigate their effects on the metabolism of vinflunine and the principal CYP450 isoform involved in the formation of metabolites M(1) and M(2) in human liver microsomes. Vinflunine was rapidly metabolized to 2 metabolites: M(1) and M(2) in human liver microsomes. M(1) and M(2) were tentatively presumed to be the N-oxide metabolite or hydroxylated metabolite and epoxide metabolite of vinflunine, respectively. Ketoconazole uncompetitively inhibited the formation of M(1), and competitively inhibited the formation of M(2), while alpha-naphthoflavone, sulfaphenazole, diethyl dithiocarbamate, tranylcypromine and quinidine had little or no inhibitory effect on the formation of M(1) and M(2). Vinflunine is rapidly metabolized in human liver microsomes, and CYP3A4 is the major human CYP450 involved in the metabolism of vinflunine.