| ObjectiveThe objective of this study is to compare the pharmacokinetics of gentiopicrin in standard gentiopicrin, Zhiganning capsules and rough gentian, the pharmacokinetics of emodin in Zhiganning capsules and Rhizoma Polygontum Cuspidatum, and the distribution of gentiopicrin in different major organs through Reversed Phase High Performance Liquid Chromatography (RP-HPLC) and Nonaqueous RP-HPLC in rat models, in order to provide guidance in the determination of dosing schemes for Zhiganning capsules and new approaches in the effect mechanism of Zhiganning capsules.MethodsThe methods of quick determination of gentiopicrin serum concentration in rats by RP-HPLC and quick determination of emodin concentration by Nonaqueous RP-HPLC were established for this study. The rats were divided into gentiopicrin group and emodin group and the drugs were administered orally. Blood samples were collected at the eyeground veins, with or without heparin added as the anticoagulant. The serum samples taken from the gentiopicrin group were added with three-times methanol in volume to deposit proteins. The supernatant was filtered to determine the blood concentration of gentiopicrin by RP-HPLC. The stationary phase was C18, the mobile phase was acetonitrile-water (20:80) and the detector was used at 270nm. The plasma samples taken from the emodin group were hydrolyzed with 30% H2SO4 and then extracted with aether. The concentration of emodin was determined by RP-HPLC. The stationary phase was C18, the mobile phase was methanol- glacial acetic acid (99.9:0.1) and the detector was used at 254nm. The results were calculated with 3P97 program. The concentration-time curves were fitted. A time point was selected in the absorption phase, the distribution phase and the clearance phase respectively. Tissue samples were collected from major organs and were homogenated. After treated with the same methods as serum samples drug concentrations were determined by RP-HPLC. Some other rats were divided into Rhizoma Polygontum Cuspidatum group and Zhiganning capsule group and the drugs were administered orally. The rats were bred in metabolism cages. Excrement and urine samples were collected and were extracted with aether. Drug concentrations were determined by RP-HPLC.ResultsIn the gentiopicrin group, standard gentiopicrin, Zhiganning capsules and grough gentian containing the same amount of gentiopicrin were administered orally. The data of dynamic blood concentrations of the drug were calculated with pharmacokinetic software. The concentration-time profiles of gentiopicrin fit two-compartment model. The pahrmacokinetic parameters are listed below. In the standard gentiopicrin group t1/2α/h was 0.39±0.08, t1/2β/h was 0.64±0.03, tmax/h was 0.57±0.05, Cmax (the maximal concentration) /μg·ml-1 was 6.16±1.17, AUC(0～∞) (area under the curve)/μg·ml-1·h was 10.7±2.3, and CL(s) (clearance)/L·h-1·kg-1 was 8.11±1.81. In the rough gentian extraction group t1/2α/h was 0.77±0.28, t1/2β/h was 1.00±0.14, tmax/h was 1.09±0.14, Cmax/μg·ml-1 was 6.54±0.87, AUC(0～∞) /μg·ml-1·h was 22.2±4.0 and CL(s) /L·h-1·kg-1 was 4.05±0.80. In the Zhiganning capsule group t1/2α was 0.86±0.11, t1/2β was 1.17±.20, tmax was 1.13±0.10, Cmax/μg·ml-1 was 7.44±1.52, AUC(0～∞) /μg·ml-1·h was 25.2±4.4 and CL(s) /L·h-1·kg-1 was 3.34±0.73. The differences between the standard gentiopicrin group and the other two groups are statistically significant, while the differences between the latter two groups are not statistically significant. The differences in Cmax in the three groups are not statistically significant. The distribution of gentiopicrin in different organs. Gentiopicrin is broadly distributed in different organs. It is concentrated in such organs as small intestine, liver, spleen, kidney and fat tissue. In rough gentian group, the concentration was 5.44±3.24 (μg/g,μg/ml) in fat tissue and 21.9±17.2 (μg/g,μg/ml) in the liver at 0.5h, 57.1±42.0*(μg/g,μg/ml) in fat tissue, 27.1±11.2*(μg/g,μ...
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