A. Ryrfeldt, S. Edsbäcker, R. Pauwels
Apr 1, 1984
Citations
1
Influential Citations
48
Citations
Quality indicators
Journal
Clinical Pharmacology & Therapeutics
Abstract
Budesonide is a potent nonhalogenated glucocorticoid consisting of a 1/1 mixture of the two epimers 22R and 22S. The kinetics of these epimers were studied in six healthy male subjects after intravenous administration of 500 µg 3H‐budesonide. Estimation of the epimer concentrations in plasma was made possible by development of an HPLC method for simultaneous separation and quantification. The plasma t½, distribution volume (Vβ), and plasma clearance for epimer 22R were (X̄ ± SD) 2.66 ± 0.57 hr, 425 ± 100 l, and 117 ± 40 l/hr. The corresponding values for epimer 22S were 2.71 ± 0.69 hr, 245 ± 38 l, and 67 ± 19 l/hr. Differences in Vβ and plasma clearance between the two were significant. The larger Vβ noted for epimer 22R may be a result of higher tissue affinity. The high plasma clearance for both epimers should largely reflect their high rate of liver biotransformation.