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Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment

Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment
Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment
CYP3A4 constitutes the major liver cytochrome P450 isoenzyme and is responsible for the oxidation of more than 50% of all known drugs. Human variability in kinetics for this pathway has been quantified using a database of 15 compounds metabolised extensively (>60%) by this CYP isoform in order to develop CYP3A4-related uncertainty factors for the risk assessment of environmental contaminants handled via this route.
Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration–time curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was greater for the oral route (46%, 12 compounds) than for the intravenous route (32%, 14 compounds). The physiological and molecular basis for the difference between these two routes of exposure is discussed. In relation to the uncertainty factors used for risk assessment, the default kinetic factor of 3.16 would be adequate for adults, whereas a CYP3A4-related factor of 12 would be required to cover up to 99% of neonates, which have lower CYP3A4 activity.
human variability, pharmacokinetics, cyp3a4, uncertainty factors, risk assessment, sensitive subgroups
0278-6915
201-224
Dorne, J.L.C.M.
bb24d5c7-c4fd-445a-9785-0a03d216fdc2
Walton, K.
024c9ff2-0a40-4fda-a213-db73d9971871
Renwick, A.G.
596705ab-5418-4e02-9ad7-c4309326df46
Dorne, J.L.C.M.
bb24d5c7-c4fd-445a-9785-0a03d216fdc2
Walton, K.
024c9ff2-0a40-4fda-a213-db73d9971871
Renwick, A.G.
596705ab-5418-4e02-9ad7-c4309326df46

Dorne, J.L.C.M., Walton, K. and Renwick, A.G. (2003) Human variability in CYP3A4 metabolism and CYP3A4-related uncertainty factors for risk assessment. Food and Chemical Toxicology, 41 (2), 201-224. (doi:10.1016/S0278-6915(02)00209-0).

Record type: Article

Abstract

CYP3A4 constitutes the major liver cytochrome P450 isoenzyme and is responsible for the oxidation of more than 50% of all known drugs. Human variability in kinetics for this pathway has been quantified using a database of 15 compounds metabolised extensively (>60%) by this CYP isoform in order to develop CYP3A4-related uncertainty factors for the risk assessment of environmental contaminants handled via this route.
Data were analysed from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating primarily to chronic exposure [metabolic and total clearances, area under the plasma concentration–time curve (AUC)] and acute exposure (Cmax). Interindividual variability in kinetics was greater for the oral route (46%, 12 compounds) than for the intravenous route (32%, 14 compounds). The physiological and molecular basis for the difference between these two routes of exposure is discussed. In relation to the uncertainty factors used for risk assessment, the default kinetic factor of 3.16 would be adequate for adults, whereas a CYP3A4-related factor of 12 would be required to cover up to 99% of neonates, which have lower CYP3A4 activity.

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More information

Published date: 2003
Keywords: human variability, pharmacokinetics, cyp3a4, uncertainty factors, risk assessment, sensitive subgroups

Identifiers

Local EPrints ID: 27030
URI: http://eprints.soton.ac.uk/id/eprint/27030
ISSN: 0278-6915
PURE UUID: 0620559e-cfea-49a5-9381-8cf1aaf91923

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Date deposited: 26 Apr 2006
Last modified: 15 Mar 2024 07:15

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Contributors

Author: J.L.C.M. Dorne
Author: K. Walton
Author: A.G. Renwick

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