Heterogeneity of CYP3A isoforms metabolizing erythromycin and cortisol.

Journal Article (Journal Article)

The N-demethylation of erythromycin and 6 beta-hydroxylation of cortisol are both functions of the glucocorticoid-inducible CYP3A in human liver microsomes. To determine whether 6 beta-hydroxylation and erythromycin N-demethylation are catalyzed by similar or distinct CYP3A isoforms, erythromycin N-demethylase activity, as reflected by the recently described 14[C]-erythromycin breath test, was compared with urinary 6 beta-hydroxycortisol/cortisol ratios, a measure of cortisol 6 beta-hydroxylase activity, in nine patients. Erythromycin N-demethylation varied fourfold and 6 beta-hydroxycortisol/cortisol ratios varied sevenfold among the subjects; no correlation was found between these activities (r2 = 0.065). New noninvasive tests of CYP3A strongly suggest cortisol 6 beta-hydroxylation and erythromycin N-demethylation are performed by distinct CYP3A isoforms.

Full Text

Duke Authors

Cited Authors

  • Hunt, CM; Watkins, PB; Saenger, P; Stave, GM; Barlascini, N; Watlington, CO; Wright, JT; Guzelian, PS

Published Date

  • January 1992

Published In

Volume / Issue

  • 51 / 1

Start / End Page

  • 18 - 23

PubMed ID

  • 1732074

International Standard Serial Number (ISSN)

  • 0009-9236

Digital Object Identifier (DOI)

  • 10.1038/clpt.1992.3


  • eng

Conference Location

  • United States