Short time kinetics of deoxycorticosterone, deoxycortisol, corticosterone and cortisol during single dose metyrapone...

In 4 young healthy males, serum levels of 11-deoxycortisol (S), cortisol (F), 11-deoxycorticosterone (DOC) and corticosterone (B) were determined at short intervals after oral administration of 30 mg/kg of metyrapone (M) at midnight. 11-hydroxylase blockade was calculated from the formula (formula: see text). Significant blockade was demonstrable 15 to 30 min after drug administration. Maximum blockade (greater than 90%) was found between 2 and 4 a.m., and fell to 60-70% at 8 a.m. The profile of blockade was very similar in all the subjects, although the absolute early rise in steroid levels showed large inter-individual differences. The F level at 8 a.m. (only slightly suppressed under these conditions) is not a safe indicator of adequate 11-hydroxylase blockade.