Anthraquinone pharmacokinetics in Xiexin decoction and the different combinations of its constituent herbs.

Xiexin decoction (XXD), a classical pyretolytic formulation, is composed of Rhei rhizoma (DH) Radix scutellaria (HQ) and Coptis chinensis (HL), and commonly used in the clinical setting. The aim of this study was to investigate the pharmacokinetic differences between the five anthraquinones it contains (aloe-emodin, rhein, emodin, chrysophanol and physcion) in rats after the oral administration of XXD and after the administration of the different combinations of its constituent herbs. Twenty rats were divided into four groups and randomly administered one of the four extracts: DH, DH and HQ (DH-HQ), DH and HL (DH-HL), and XXD (DH-HQ-HL) via intragastric gavage (i.g.). Anthraquinone concentrations in the plasma were determined by an HPLC technique. Pharmacokinetic parameters were calculated from the plasma concentration time data. Compared with DH alone, the DH-HL combination showed maximum plasma concentration decreased (Cmax) and area under curve (AUC) for the values anthraquinones, and a prolonged eliminatun half life (T(1/2)) for rhein, while the DH-HQ combination showed a decrease Cmax for rein and a prolonged T(1/2) for aloe-emodin and physcion. Finally, XXD (DH-HQ-HL) administration resulted in an increased AUC for all five anthraquinones compared to DH-HL, and increased the total of AUC for rhein, emodin, chrysophanol and physcion compared to DH alone. These results showed that the oral bioavailability of the five anthraquinones was significantly decreased by combining DH with HL, whereas HQ increased the amounts of absorbed anthraquinones (except for aloe-emodin), and weakened the effect of HL which inhibited the absorption of anthraquinones.