Urinary excretion of 6 beta-hydroxycortisol as an in vivo marker for CYP3A induction: applications and recommendations.
OBJECTIVE
To evaluate the usefulness of 6 beta-hydroxycortisol as a screen for CYP3A induction in early-phase drug development.


METHODS
Five groups of 12 healthy elderly men were randomized to one of five treatment regimens: (1) 600 mg rifampin (INN, rifampicin) once daily, (2) placebo once daily, (3) 40 mg SB 216469 twice a day, (4) 60 mg SB 216469 twice a day, or (5) 40 mg SB 216469 three times a day. All medications were taken orally and administered for 7 consecutive days. Urine was collected over a 24-hour period for each subject before administration and on the last day of administration for each respective regimen for measurement of 6 beta-hydroxycortisol and 17-hydroxycorticosteroid concentrations.


RESULTS
Subjects in the rifampin group had a significant increase from predose value in the 24-hour urinary excretion of 6 beta-hydroxycortisol and the ratio of 6 beta-hydroxycortisol to 17-hydroxycorticosteroid. All 12 subjects in the rifampin group had increases in 6 beta-hydroxycortisol excretion, whereas 11 of 12 had an increase in the ratio. The placebo and three active treatment groups did not show significant changes in either parameter.


CONCLUSIONS
Urinary excretion of 6 beta-hydroxycortisol may be useful as a screening tool in early-phase development to assess the potential for an investigational drug to induce CYP3A.
Kovacs
S J
SJ
SmithKline Beecham Clinical Pharmacology Unit, Presbyterian Medical Center-University of Pennsylvania Health System, Philadelphia, USA.
Martin
D E
DE
Everitt
D E
DE
Patterson
S D
SD
Jorkasky
D K
DK
D015065:17-Hydroxycorticosteroids / Q000652:urine; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D000904:Antibiotics, Antitubercular / Q000008:administration & dosage / Q000378:metabolism; D001189:Aryl Hydrocarbon Hydroxylases; D002867:Chromones / Q000008:administration & dosage / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004334:Drug Administration Schedule; D004790:Enzyme Induction; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000652:urine; D008297:Male; D010089:Oxidoreductases, N-Demethylating / Q000096:biosynthesis*; D012016:Reference Values; D012293:Rifampin / Q000008:administration & dosage / Q000378:metabolism
D015065:17-Hydroxycorticosteroids; D000317:Adrenergic alpha-Antagonists; D000904:Antibiotics, Antitubercular; D002867:Chromones; C099870:Rec 15-2739; C001380:6 beta-hydroxycortisol; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; D051544:Cytochrome P-450 CYP3A; D010089:Oxidoreductases, N-Demethylating; D012293:Rifampin; D006854:Hydrocortisone