Baicalin reduces ciclosporin bioavailability by inducing intestinal p‐glycoprotein in rats

Objectives To investigate the effects of multiple doses of baicalin (BG) on the pharmacokinetics of ciclosporin (CsA) in rats and the potential mechanisms. Methods Pharmacokinetic parameters of CsA were determined in male rats after administration of CsA (3 mg/kg, i.g. or i.v.) to rats in the presence and absence of BG (80 mg/kg, i.g. or i.v.) for 7 days. The livers and intestines of rats were isolated and the CYP3A and p‐glycoprotein (P‐gp) expression were analysed. The effect of BG on the intestinal absorptive behaviour of CsA was also investigated using in‐vitro everted rat gut sac model. Key findings Baicalin (80 mg/kg, i.v., 7 days) had no effect on the intravenously administered CsA. However, BG (80 mg/kg, i.g., 7 days) significantly decreased the Cmax, AUC0–t and AUC0–∞ of orally administered CsA by 38, 26 and 25%, respectively (P