OBJECTIVETo investigate the absorption mechanism of loganin at different intestine segments of rats and the influence of the drug solution concentration, pH, P-gp inductor.

METHODRats were randomly divided into 10 groups, high, middle and low concentration groups (0.1, 0.025, 0.012 5 mg x mL(-1)), duodenum, jejunum and ileum groups (0.013 mg x mL(-1)), high, middle and low pH groups (0.013 mg x mL(-1)), inducer group (0.013 mg x mL(-1)). The intestine cannulation was performed for in situ recirculation. Loganin concentration in the flux was measured by the reversed phase HPLC.

RESULTWhen the concentration was raised from 0.012 5 to 0.1 mg x mL(-1), the uptake of loganin was linearly increased, and no change of Ka is not found. The pH of flux has no effect on drug absorption. The absorbed dose and Ka sequence (from high to low) of loganin at different intestine segments is ileum, duodenum, jejunum. Furthermore, P-gp inductor RFP has effect on the intestinal absorption.

CONCLUSIONThe absorption of loganin in intestine of rat is a first-order kinetics, the absorption mechanism is probably the passive diffusion. It has specific absorption locus and access to locating administration, meanwhile it's the P-gp substrate, and could increase its fraction of bioavailability by corporation with P-gp inhibitor.