Pharmacokinetics of Ephedrine and Pseudoephedrine after Oral Administration of Kakkonto to Healthy Male Volunteers

Abstract

The pharmacokinetics of serum ephedrine and pseudoephedrine as the indexed reference ingredients of Kampo Kakkonto (ge-gen-tang in Chinese) were compared after the oral administration of 2.5 g and 3.75 g of Kakkonto extract. The mean maximal serum concentrations of ephedrine and pseudoephedrine obtained after the administration at 3.75 g were 1.50- and 1.58-fold higher (p<0.05), respectively, than those obtained after the administration of 2.5 g, whereas the time required to reach the maximal concentration did not significantly differ between the two doses. The mean areas under the concentration-time curves of ephedrine and pseudoephedrine obtained after the 3.75 g of Kakkonto were 1.31- and 1.48-fold higher (p<0.05), respectively, than those obtained after the 2.5 g dose, while no significant differences were observed in the mean residence time and elimination rate constant of the terminal phase between the doses. Disposition profiles showed that the kinetic behavior of ephedrine and pseudoephedrine were largely linear at the doses examined.