Pharmacokinetic Study Of Zhizi Bopi Decoction In Vivo And In Vitro

Chinese herbal medicines are prescribed in combination based on the theory oftraditional Chinese herbal medicine (TCHM) to increase or decrease the efficacy. Theinvestigation of the rule of prescription compatibility is of great significance for themodernization of traditional Chinese medicine, is an indispensable part. Using thepharmacokinetic research on traditional Chinese medicine compatibility, can clarify thechemical composition after compatibility in the body of the changing process ofabsorption, distribution, metabolism and excretion, can investigate the change in contentof compounds with the change of time. True to clarify the effective substance basis ofChinese compound formula. Because the traditional Chinese medicine compound isvery complex, one or several major activity ingredients are always selected as indicativecompounds and the interactions of ingredients in herb or prescription are clarified basedon the pharmacokinetic behavior of selected compounds.Drug transport across the membrane is the precondition for the process of drug in thebody, as well as the essential to play an active and runs through the whole process ofdrug in the body, the study of drug transport across the membrane to improve the effectand bioavailability of drug is of great significance. Currently the most widely used drug absorption model in vitro are human colon cancer cells model and Madin-Darby caninekidney model. They have good correlation in terms of drug transport across themembrane. But compared to Caco-2cells, MDCK has the advantage of fast growth.Form a complete monolayer only5days, the amount and type of membrane surfacereceptor was significantly less than Caco-2cells, this simplicity makes MDCK cellmodel has high reproducibility of experiment results.Zhizi Bopi Decoction, containing Fructus Gardeniae, Cortex Phellodendri and RadixGlycyrrhizae, and was first described by Zhang Zhongjing in ‘Treatise on FebrileDiseases (Shang Han Lun)’. It has attracted a great deal of attention for its effects ondamp-heat jaundice. Geniposide is the main active ingredient of Fructus Gardeniae andhas been used as a quality control marker of Fructus Gardeniae in Chinesepharmacopoeia. Pharmacological studies have exhibited that geniposide hasanti-inflammatory, anti-atherosclerosis, antipyretic, cholagogue, an-tithrombosisefficacy. But the compatibility of Zhizi Bopi Decoction and the mutual influencebetween herbs were not reported. In this study, ZZBPD was choosed as a tool drug.According to published pharmacodynamic study results and TCM theory, geniposidewas chosen as an indicative effective compound to investigate the pharmacokinetics ofZZBPD and different combinations of the constituent herbs of ZZBPD. And on thisbasis, through the research in vitro model, further to study the transport of geniposideand geniposide in Zhizi Bopi Decoction in MDCK cell membrane model.1. Pharmacokinetic study on different compatibilities of Zhizi Bopi Decoction in RatsTo obtain pharmacokinetics parameters of geniposide in pure geniposide, ZZ,ZZ-HB, ZZ-GC and ZZBPD and to investigate the effect of the different recipes ofZZBPD on the pharmacokinetics of geniposide.30rats were divided into5groups, and pure geniposide, ZZ, ZZ-HB, ZZ-GC and ZZBPD were orally administrated,respectively. The plasma concentration of four recipes at0.08,0.25,0.5,0.75,1,1.5,2,4,6,8and10h were determined by HPLC, and the pharmacokinetics parameters ofgeniposide in these recipes were consequently computed by software program3P97.The differences of the predominant parameters of geniposide in rat plasma of the5groups were considered to be significant (p <0.05). Compared to administration ofgeniposide alone, the pharmacokinetic parameters (AUC0t, AUC0∞, T1/2) wereremarkably enhanced following oral administration of ZZ, ZZ-HB, ZZ-GC, ZZBPD.The Cmax, T1/2, AUC0tand AUC0∞of ZZBPD were remarkably enhanced compared toother four groups. The AUC0t, AUC0∞, T1/2of ZZ-HB, ZZ-GC and ZZBPD werehigher than ZZ. The Tmaxof ZZ-GC and ZZBPD were longer than ZZ and ZZ-HB.Different recipes of ZZBPD had different impact on the pharmacokinetics of geniposide.The bioavailability of geniposide in decoctions were higher than in monomer and thebioavailability of geniposide in ZZBPD was higher than other groups. This suggests therationality of the compatibility of the compound.2. Transport of geniposide and geniposide in Zhizi Bopi Decoction in MDCK cellmembrane modelTo study the transport of geniposide and geniposide in Zhizi Bopi Decoction inMDCK cell membrane model. The safety concentration of geniposide and Zhizi BopiDecoction in MDCK cells was determined by MTT assay. Then the MDCK cellmembrane model was used to investigate the transport of drugs. Firstly, the effects ofdrug concentration, time, P-gp inhibitor and EDTA on the absorption and transport ofgeniposide were studied systematically. Secondly, the differences were comparedbetween the transport of the same concentration geniposide as single compound and thatin Zhizi Bopi Decoction in MDCK cell model. The drug concentration was determined by HPLC to calculate the apparent permeability coefficient. Geniposide transport inMDCK cell monolayer was time and concentration dependent. P-gp inhibitors had nosignificant effect on its transport and the transport of geniposide was enhanced byEDTA. The absorption Pappof different concentrations of geniposide in Zhizi BopiDecoction were (8.96±0.35)×10-7cm·s-1,(8.95±0.38)×10-7cm·s-1and (9.16±0.30)×10-7cm·s-1, significantly higher than the absorption Pappof geniposide as singlecompound(5.85±0.44)×10-7cm·s-1,(6.88±0.38)×10-7cm·s-1and (6.31±0.19)×10-7cm·s-1(P<0.05). The transport of geniposide in MDCK cell membrane model is passivetransport and is not affected by P-gp. Geniposide may transport via the paracellularroute. The Zhizi Bopi Decoction can increase the absorption of geniposide.