[Profiles of effects of traditional oriental herbal medicines on central nervous systems in humans--assessment of saiboku-to and saiko-ka-ryukotsu-borei-to using EEG and pharmacokinetics of herbal medicine-derived ingredients as indices].

To elucidate usefulness of traditional oriental herbal medicines in psychiatric fields, we investigated their influences on central nervous systems in humans by using EEG and pharmacokinetics of herbal medicine-derived ingredients as the indices. The subjects were 12 healthy male volunteers who received single oral administration and after that received repeated oral administrations at a daily dose of Saiko-ka-ryukotsu-borei-to or Saiboku-to; EEG was recorded before administration, 1, 3, 6 hours and 10 days after administration. On direct comparison of global field powers calculated from 19-lead EEG before and after administration, it was verified that Saiboku-to possessed effects on central nervous systems. For assessment of pharmacokinetics of ingredients derived from Saiboku-to, pre- and post-treatment serum samples were assayed by HPLC and two ingredients were detected, besides individual differences being observed in their pharmacokinetic profiles. Given that these pharmacokinetics could be interpreted as the phenomena associated with Sho (traditional physical status classifications of patients), the subjects were classified into groups according to individual differences whereby quantitative pharmaco-EEG were employed to elucidate neurotropic effects of Saiboku-to. As the result, following two groups were evidenced: (1) a group demonstrating the mood elevator type after a single administration despite of no changes after repeated administrations, and (2) a group with a shift from the mood elevator type to the nootropics type being observed over time, delineating overt differences in EEG profiles among groups. Consequently, individual differences were evidenced to be involved in onset of neurotropic effects of Saiboku-to, permitting prediction of possible responses following repeated administrations by using EEG profiles. It was also suggested that neurotropic effects of respective ingredients could be anticipated by monitoring the time-course changes of both EEG and plasma levels of these ingredients. In summary, once further studies on oriental herbal medicines might progress based on efficacy assessments of respective ingredients with a clue of the present study, it is conceivable that these findings would play an important role as the objective indices in clinical application of herbal medicines in psychiatric fields, resulting in broadening the usefulness of oriental herbal medicines.