Study in situ on Rat Intestinal Absorption Mechanism and Influential Factors of ginsenosides Rb1 and Rg1 in Bazhen Decoction

To investigate the absorption of ginsenosides Rg(1) and Rb-1 in Bazhen Decoction at different intestine segments of rats and the influence of the drug solution concentration, pH, P-gp inhibitor on ones. The intestine cannulation was performed for in situ recirculation. The concentration of ginsenosides Rg(1) and Rb-1, and phenol red in the flux were measured by the reversed phase HPLC and ultraviolet spectrophotometry, respectively. The absorption of ginsenosides Rg(1) and Rb-1 in Bazhen Decoction in intestine of rat show first-order kinetics with the absorption mechanism of passive diffusion. Ginsenoside Rg(1) has specific absorption locus of duodenum and ginsenoside Rb-1 has specific absorption locus of jejunum. Meanwhile, ginsenoside Rb-1 is the P-gp substrate, and could increase its fraction of bioavailability by corporation with P-gp inhibitor.