Volume 50: 191-196, 2001

Influence of Amiodarone on Urinary Excretion of
6
b-Hydroxycortisol in Humans

S. MIČUDA1, M. HODAČ2, L. ŠIŠPERA1, P. PAŘÍZEK2, M. PLESKOT2,
G. ZIMOVÁ
1, J. CERMAN3, J. MARTÍNKOVÁ1, V. PIDRMAN2

1Department of Pharmacology, 2Second Department of Internal Medicine and 3Department of Biochemistry, Faculty of Medicine, Charles University, Hradec Králové, Czech Republic

Received June 28, 2000
Accepted August 16, 2000

Summary
The present study was undertaken to evaluate the use of cortisol 6b-hydroxylation in defining the effect of amiodarone on cytochrome CYP3A activity. To accomplish this goal, the in vivo activity of CYP3A was estimated by measuring the 24-hour urinary excretion of 6b-hydroxycortisol (6b-OHC) and by calculating 24-hour ratio of 6b-hydroxycortisol to urinary free cortisol (6b-OHC/UFC ratio). Nine cardiac patients scheduled for amiodarone treatment were recruited to participate in this study. Urine was collected over a 24-hour period from each subject before the first amiodarone administration and during the third day of oral administration of amiodarone (200 mg four times daily as a loading dose). Three days of amiodarone treatment caused a significant decrease (p<0.05) in both the 6b-OHC/UFC ratio and the 24-hour urinary excretion of 6b-OHC. These results suggest that amiodarone is an inhibitor of CYP3A activity.


Reprint requests
Stanislav Mičuda, M.D., Department of Pharmacology, Charles University in Prague, Faculty of Medicine in Hradec Králové, Šimkova 870, 50001 Hradec Králové, Czech Republic. fax.: +420-49-5513022, e-mail:
micuda@lfhk.cuni.cz


PHYSIOLOGICAL RESEARCH
© 2001 by the Institute of Physiology, Czech Academy of Sciences

ISSN 0862 - 8408

Issue 2