6-beta-hydroxycortisol and Myocardial-Ischemia

The present study was undertaken to evaluate the use of cortisol 6beta-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 6beta-hydroxycortisol (6beta-OHC) and by calculating 24-hour ratio of 6beta-hydroxycortisol to urinary free cortisol (6beta-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 6beta-OHC/UFC ratio and the 24-hour urinary excretion of 6beta3-OHC. These results suggest that amiodarone is an inhibitor of CYP3A activity.

Topics: Administration, Oral; Adult; Aged; Amiodarone; Aryl Hydrocarbon Hydroxylases; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Humans; Hydrocortisone; Middle Aged; Myocardial Ischemia; Oxidoreductases, N-Demethylating; Vasodilator Agents