Chronopharmacological study of KE-SI-TO components in mice

Influence of dosing time on pharmacological effects and toxicity of KE-SI-TO (KST) components, as well as the role of each component in the circadian rhythms of KST, was investigated in ICR male mice under an LD (12:12) cycle. The mice given Cinnamomi Cortex (258 mg/kg, i.p.) or Paeoniae Radix (258 mg/kg, i.p.) showed a significant circadian rhythm in the time spent on the hot plate with the shortest latency at 0900 and the longest one at 0100 (p < 0.01, respectively). The mice given Cinnamomi Cortex or Glycyrrhizae Radix (129 mg/kg, i.p.) showed a significant circadian rhythm with the lowest rectal temperature (RT) at 1700 and the highest one at 0500 (p < 0.01, respectively). Cinnamomi Cortex (850 mg/kg, i.p.)- or Glycyrrhizae Radix (2500 mg/kg, i.p.)-induced toxicity showed a significant circadian rhythm with the highest mortality at 1700 and the lowest one at 0500 (p < 0.05, respectively). The rhythmic patterns of the drug-induced analgesia, hypothermia and toxicity resembled the overall rhythms occurring after KST (1000 or 6000 mg/kg, i.p.) injection. These results suggest that the circadian rhythms in actions of Cinnamomi Cortex, Paeoniae Radix and Glycyrrhizae Radix are mainly responsible for the rhythm in the effects and toxicity of KST.