Cited by 472Pharmacogenetics and Drug MetabolismDrug Transport and Resistance MechanismsMetal-Catalyzed Oxygenation Mechanisms

Comparative metabolic capabilities of CYP3A4, CYP3A5, and CYP3A7

Williams, J.Andrew, Ring, Barbara J., Cantrell, Varon E., Jones, David R., Eckstein, James, Ruterbories, Kenneth, Hamman, Mitchell A., Hall, Stephen D. +1 more·2002·Drug Metabolism and Disposition

Abstract

The human cytochromes P450 (P450) CYP3A contribute to the biotransformation of 50% of oxidatively metabolized drugs. The predominant hepatic form is CYP3A4, but recent evidence indicates that CYP3A5 contributes more significantly to the total liver CYP3A than was originally thought. CYP3A7 is the major fetal form and is rarely expressed in adults. To compare the metabolic capabilities of CYP3A forms for 10 substrates, incubations were performed using a consistent molar ratio (1:7:9) of recombinant CYP3A, P450 reductase, and cytochrome b5. A wide range of substrate concentrations was examined to determine the best fit to kinetic models for metabolite formation. In general, K(m) or S(50) values for the substrates were 3 to 4 times lower for CYP3A4 than for CYP3A5 or CYP3A7. For a more direct comparison of these P450 forms, clearance to the metabolites was determined as a linear relationship of rate of metabolite formation for the lowest substrate concentrations examined. The clearance for 1'-hydroxy midazolam formation at low substrate concentrations was similar for CYP3A4 and CYP3A5. For CYP3A5 versus CYP3A4, clearance values at low substrate concentrations were 2 to 20 times lower for the other biotransformations. The clearance values for CYP3A7-catalyzed metabolite formation at low substrate concentrations were substantially lower than for CYP3A4 or CYP3A5, except for clarithromycin, 4-OH triazolam, and N-desmethyl diltiazem (CYP3A5 - CYP3A7). The CYP3A forms demonstrated regioselective differences in some of the biotransformations. These results demonstrate an equal or reduced metabolic capability for CYP3A5 compared with CYP3A4 and a significantly lower capability for CYP3A7.

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Crossref · 10.1124/dmd.30.8.883

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Authors
Williams, J. A., Ring, B. J., Cantrell, V. E., Jones, D. R., Eckstein, J., Ruterbories, K., Hamman, M. A., Hall, S. D., & Wrighton, S. A.
Affiliations
Eli Lilly (United States) (US)
Venue
Drug Metabolism and Disposition
Publisher
Elsevier BV
Published
2002-08
Volume
30
Issue
8
Pages
883-891
ISSN
0090-9556 (ISSN-L)
OpenAlex
W2052406081
Cited by
471
References
32
Citations by year
2026: 10 · 2025: 9 · 2024: 11 · 2023: 14 · 2022: 21 · 2021: 31 · 2020: 16 · 2019: 21 · 2018: 18 · 2017: 18 · 2016: 14 · 2015: 22 · 2014: 15 · 2013: 24 · 2012: 14
FWCI
19.66
Type
journal article
Language
en
Open access
closed
Locations
  • Drug Metabolism and Disposition (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Pharmacogenetics and Drug Metabolism
  • Health Sciences › Medicine › Oncology › Drug Transport and Resistance Mechanisms
  • Physical Sciences › Chemistry › Inorganic Chemistry › Metal-Catalyzed Oxygenation Mechanisms
Keywords
CYP3A4, CYP3A5, CYP3A7, cytochrome P450, drug metabolism, midazolam hydroxylation, clarithromycin, regioselectivity, enzyme kinetic parameters
MeSH terms
Alprazolam, Aryl Hydrocarbon Hydroxylases, Biotransformation, Coumarins, Cytochrome P-450 Enzyme System, Diltiazem, Estradiol, Humans, Kinetics, Microsomes, Liver, Midazolam, Nifedipine, Tamoxifen, Testosterone, Triazolam, Cytochromes b5, Clarithromycin, Cytochrome P-450 CYP3A, In Vitro Techniques

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