[Circadian fluctuations of pharmacokinetic parameters after oral administration of hexobarbital (author's transl)]

To 4 male and 2 female subjects hexobarbital was applied orally at different times of the day: 2, 10, 18 h. Serum concentrations of hexobarbital were determined by HPLC procedure and the resulting pharmacokinetic parameters in a rotating iterative program. Application at 18 h resulted in a shorter invasion time, a higher maximum concentration and a delayed elimination; in addition, the AUC was elevated in relation to application at 2 or 10 h. In the 2 female subjects a different pattern was observed. The results lead to the assumption that application of hexobarbital is more effective in the evening than in the morning.