Abstract:

AIM: To compare the pharmacokinetics of baicalin(BG)and baicalein (BL) in rats by intravenous administration. METHODS: Two groups of rats (5 per group) received an intravenous administration of BG or BL at equimolar dose of 37 μmol/kg and dosing volume of 10 mL/kg. After administration, blood samples were collected in 1.5 mL heparinized polythene tubes, at 0 (pre-dose), 0.08, 0.17, 0.33, 0.5, 1, 2, 4, 6, 8,12, 24 h after dosing, simultaneous determination of baicalin and baicalein in plasma by HPLC-MS / MS. RESULTS: BG and BL could be detected in all plasma after baicalein/baicalin was administrated intravenously to rats. In BG group, the C _max of BG was （24.5±18.3）nmol/mL，AUC _0-24 was （13.3±11.6）nmol·mL^-1·h^-1 group. In BL group , the C _max of BL was （10.5±5.1）nmol/mL，AUC _0-24 was （18.2±4.9）nmol·mL^-1·h^-1. The rate of BG transformed into BL was 26.5% in the BG group. The rate of BL transformed into BG was 35%. CONCLUSION: The Cmax of BL in BL group was significantly higher than that of BG in BG group after intravenous administration of equimolar dose of BG/BL; however, the AUC _0-24 value was opposite. It might be caused by the higher lipophilicity, the wider distribution; the lower clearance rate of baicalein. It is suggested that baicalin and baicalein can be transformed into each other in vivo. The rate of BL transforming into BG is significantly higher than that of BG transforming into BL.

Key words: baicalein, baicalin, intravenous administration, pharmacokinetic