Unit

UNIT 4.13 Human Cytochrome P450: Metabolism of Testosterone by CYP3A4 and Inhibition by Ketoconazole

  1. Khawja A. Usmani,
  2. Jun Tang

Published Online: 1 JUN 2004

DOI: 10.1002/0471140856.tx0413s20

Current Protocols in Toxicology

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.

Author Information

  1. North Carolina State University, Raleigh, North Carolina

Publication History

  1. Published Online: 1 JUN 2004
  2. Published Print: JUN 2004

Abstract

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.

Keywords:

  • P450;
  • CYP3A4;
  • testosterone;
  • ketoconazole;
  • inhibition