UNIT 4.13 Human Cytochrome P450: Metabolism of Testosterone by CYP3A4 and Inhibition by Ketoconazole
Published Online: 1 JUN 2004
Copyright © 2003 by John Wiley and Sons, Inc.
Lab Protocol Title
Current Protocols in Toxicology
How to Cite
Usmani, K. A. and Tang, J. 2004. Human Cytochrome P450: Metabolism of Testosterone by CYP3A4 and Inhibition by Ketoconazole. Current Protocols in Toxicology. 20:4.13:4.13.1–4.13.9.
- Published Online: 1 JUN 2004
- Published Print: JUN 2004
This unit describes methods for measuring CYP3A4 activity using testosterone as a specific substrate, and for measuring CYP3A4 inhibition using ketoconazole as a selective inhibitor of testosterone oxidation. CYP3A4 is one of the most important and most abundant drug-metabolizing CYP isoforms in human liver microsomes (∼40% of total CYP), and it has the broadest substrate specificity. It is important to determine whether CYP3A4 is involved in its metabolism.