Circadian changes in pharmacokinetics of cyclosporin in healthy volunteers.

Circadian changes in the pharmacokinetics of cyclosporin were evaluated after oral administration of the drug, 300 mg, at 09:00 and 20:00 to twelve healthy male subjects. At 09:00, the blood concentrations of cyclosporin were higher, the area under the blood concentration-time curve from time 0 to time infinity was significantly greater (9.70 versus 8.42 mu g.hr/ml), and the renal clearance was significantly slower (1.14 versus 1.48 ml/min) than those at 22:00. The terminal half-life, peak concentration, and time to reach peak concentration were not significantly different between two groups.