The Disconnect in Intrinsic Clearance Determined in Human Hepatocytes and Liver Microsomes Results from Divergent Cytochrome P450 Activities.

Autor: Bapiro TE; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.) tashinga.bapiro1@astrazeneca.com dermot.f.mcginnity@astrazeneca.com., Martin S; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.)., Wilkinson SD; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.)., Orton AL; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.)., Hariparsad N; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.)., Harlfinger S; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.)., McGinnity DF; Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Cambridge, United Kingdom (T.E.B., S.M., S.D.W., A.L.O., S.H., D.F.M.) and Drug Metabolism and Pharmacokinetics, Oncology Research and Development, AstraZeneca, Boston, Massachusetts (N.H.).
Jazyk: angličtina
Zdroj: Drug metabolism and disposition: the biological fate of chemicals [Drug Metab Dispos] 2023 Jul; Vol. 51 (7), pp. 892-901. Date of Electronic Publication: 2023 Apr 11.
DOI: 10.1124/dmd.123.001323
Abstrakt: Candidate drugs may exhibit higher unbound intrinsic clearances (CL int,u ) in human liver microsomes (HLMs) relative to human hepatocytes (HHs), posing a challenge as to which value is more predictive of in vivo clearance (CL). This work was aimed at better understanding the mechanism(s) underlying this 'HLM:HH disconnect' via examination of previous explanations, including passive permeability limited CL or cofactor exhaustion in hepatocytes. A series of structurally related, passively permeable (P apps > 5 × 10 -6 cm/s), 5-azaquinazolines were studied in different liver fractions, and metabolic rates and routes were determined. A subset of these compounds demonstrated a significant HLM:HH (CL int,u ratio 2-26) disconnect. Compounds were metabolized via combinations of liver cytosol aldehyde oxidase (AO), microsomal cytochrome P450 (CYP) and flavin monooxygenase (FMO). For this series, the lack of concordance between CL int,u determined in HLM and HH contrasted with an excellent correlation of AO dependent CL int,u determined in human liver cytosol[Formula: see text], r 2 = 0.95, P < 0.0001). The HLM:HH disconnect for both 5-azaquinazolines and midazolam was as a result of significantly higher CYP activity in HLM and lysed HH fortified with exogenous NADPH relative to intact HH. Moreover, for the 5-azaquinazolines, the maintenance of cytosolic AO and NADPH-dependent FMO activity in HH, relative to CYP, supports the conclusion that neither substrate permeability nor intracellular NADPH for hepatocytes were limiting CL int,u Further studies are required to identify the underlying cause of the lower CYP activities in HH relative to HLM and lysed hepatocytes in the presence of exogenous NADPH. SIGNIFICANCE STATEMENT: Candidate drugs may exhibit higher intrinsic clearance in human liver microsomes relative to human hepatocytes, posing a challenge as to which value is predictive of in vivo clearance. This work demonstrates that the difference in activity determined in liver fractions results from divergent cytochrome P450 but not aldehyde oxidase or flavin monooxygenase activity. This is inconsistent with explanations including substrate permeability limitations or cofactor exhaustion and should inform the focus of further studies to understand this cytochrome P450 specific disconnect phenomenon.
(Copyright © 2023 by The American Society for Pharmacology and Experimental Therapeutics.)
Databáze: MEDLINE
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