Pharmacokinetics of liquiritigenin and its two glucuronides, M1 and M2, in rats with acute hepatitis induced by D-galactosamine/lipopolysaccharide or CCl4

1. Cytoprotective effects of liquiritigenin (LQ) against liver injuries have been reported, but its pharmacokinetics has not been studied in acute hepatitis. Thus, pharmacokinetics of LQ and its two conjugated glucuronide metabolites: 4'-O-glucuronide (M1) and 7-O-glucuronide (M2), in rats with acute hepatitis induced by D-galactosamine/lipopolysaccharide (GalN/LPS) rats or carbon tetrachloride-treated (CCl4-treated) rats were evaluated. 2. LQ was administered intravenously (20 mg kg(-1)) and orally (50 mg kg(-1)) to control GalN/LPS and CCl4-treated rats. Expression of uridine 5'-diphospho-glucuronosyltransferases 1A (UGT1A) and in vitro metabolism of LQ in hepatic and intestinal microsomes were also measured. 3. After intravenous administration of LQ, area under the plasma concentration-time curve (AUC) of LQ in GalN/LPS rats was significantly smaller than that in controls due to faster non-renal clearance, as a result of its greater free fraction in plasma and faster hepatic blood flow rate than the controls. In CCl4-treated rats, the AUC(M1,) (0-8 h)/AUC(LQ) and AUC(M2,) (0-8 h)/AUC(LQ) ratios were significantly greater than the controls due to decrease in biliary excretion of M1 and M2. However, no significant pharmacokinetic changes were observed in both acute hepatitis rats after oral administration due to comparable intestinal metabolism of LQ. 4. Modification of oral dosage regimen of LQ may not be necessary in patients with acute hepatitis; but human studies are required.