TY - JOUR
T1 - Characterization of kinetics of human cytochrome P450s involved in bioactivation of flucloxacillin
T2 - inhibition of CYP3A-catalysed hydroxylation by sulfaphenazole
AU - Dekker, Stefan J.
AU - Dohmen, Floor
AU - Vermeulen, Nico P.E.
AU - Commandeur, Jan N.M.
PY - 2019/2/1
Y1 - 2019/2/1
N2 - Background and Purpose: The aim of this study was to characterize the human cytochrome P450s (CYPs) involved in oxidative bioactivation of flucloxacillin to 5-hydroxymethyl flucloxacillin, a metabolite with high cytotoxicity towards biliary epithelial cells. Experimental Approach: The CYPs involved in hydroxylation of flucloxacillin were characterized using recombinant human CYPs, pooled liver microsomes in the presence of CYP-specific inhibitors and by correlation analysis using a panel of liver microsomes from 16 donors. Key Results: Recombinant CYPs showing the highest specific activity were CYP3A4, CYP3A7 and to lower extent CYP2C9 and CTP2C8. Michaelis–Menten enzyme kinetics were determined for pooled human liver microsomes, recombinant CYP3A4, CYP3A7 and CYP2C9. Surprisingly, sulfaphenazole appeared to be a potent inhibitor of 5′-hydroxylation of flucloxacillin by both recombinant CYP3A4 and CYP3A7. Conclusions and Implications: The combined results show that the 5′-hydroxylation of flucloxacillin is primarily catalysed by CYP3A4, CYP3A7 and CYP2C9. The large variability of the hepatic expression of these enzymes could affect the formation of 5′-hydroxymethyl flucloxacillin, which may determine the differences in susceptibility to flucloxacillin-induced liver injury. Additionally, the strong inhibition in CYP3A-catalysed flucloxacillin metabolism by sulfaphenazole suggests that unanticipated drug–drug interactions could occur with coadministered drugs.
AB - Background and Purpose: The aim of this study was to characterize the human cytochrome P450s (CYPs) involved in oxidative bioactivation of flucloxacillin to 5-hydroxymethyl flucloxacillin, a metabolite with high cytotoxicity towards biliary epithelial cells. Experimental Approach: The CYPs involved in hydroxylation of flucloxacillin were characterized using recombinant human CYPs, pooled liver microsomes in the presence of CYP-specific inhibitors and by correlation analysis using a panel of liver microsomes from 16 donors. Key Results: Recombinant CYPs showing the highest specific activity were CYP3A4, CYP3A7 and to lower extent CYP2C9 and CTP2C8. Michaelis–Menten enzyme kinetics were determined for pooled human liver microsomes, recombinant CYP3A4, CYP3A7 and CYP2C9. Surprisingly, sulfaphenazole appeared to be a potent inhibitor of 5′-hydroxylation of flucloxacillin by both recombinant CYP3A4 and CYP3A7. Conclusions and Implications: The combined results show that the 5′-hydroxylation of flucloxacillin is primarily catalysed by CYP3A4, CYP3A7 and CYP2C9. The large variability of the hepatic expression of these enzymes could affect the formation of 5′-hydroxymethyl flucloxacillin, which may determine the differences in susceptibility to flucloxacillin-induced liver injury. Additionally, the strong inhibition in CYP3A-catalysed flucloxacillin metabolism by sulfaphenazole suggests that unanticipated drug–drug interactions could occur with coadministered drugs.
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U2 - 10.1111/bph.14548
DO - 10.1111/bph.14548
M3 - Article
C2 - 30447161
AN - SCOPUS:85059064332
VL - 176
SP - 466
EP - 477
JO - British Journal of Pharmacology
JF - British Journal of Pharmacology
SN - 0007-1188
IS - 3
ER -