Experimental Research On Drug Interaction Of Combined Therapy And On Liver Targeted Ribavirin Against HCV

PART T·WO：Experimental research on drug interaction of combined therapy againstHCVObjectiveTo investigate the effects of diammonium glycyrrhizinate, silymarin, bicyclol andoxymatrine on safety and pharmacokinetics of ribavirin (RBV) after co-administration withRBV in rat.Materials and Methods1. The cytotoxicity of RBV and its combination with silymarin, diammoniumglycyrrhizinate, bicyclol and oxymatrine against HepG2cells was investigated by MTTassay.2. Silymarin, diammonium glycyrrhizinate, bicyclol and oxymatrine were co-administratedwith180mg/kg or60mg/kg of RBV for10or14days and their effects on toxicity ofribavirin were investigated.3. Silymarin, diammonium glycyrrhizinate, bicyclol and oxymatrine were co-administratedwith RBV in rats and their effects on the pharmacokinetics of ribavirin and its metabolitewas investigated by LC-MS/MS.Results1. Silymarin was effective to protect the HepG2cells against RBV induced cytotoxicity andthe protection rate were101.14%and215.05%at30μM and100μM respectively, whilediammonium glycyrrhizinate, bicyclol and oxymatrine were not effective.2. Co-administration of silymarin, diammonium glycyrrhizinate, bicyclol or oxymatrinewith RBV (180mg/kg) results decreasing of the mortality but their effect on the bodyweight was not significant. Silymarin and bicyclol can significantly antagonize the reduction of WBC resulted by oral administration of RBV; Silymarin, diammoniumglycyrrhizinate, bicyclol or oxymatrine can reverse the elevation of PLT induced by RBV;diammonium glycyrrhizinate significantly inhibited the elevation of ALT induced byRBV and bicyclol and oxymatrine inhibited the elevation of AST.3. A rapid, sensitive and highly selective liquid chromatography/tandem massspectrometry (LC-MS/MS) assay was developed to quantitatively determineRBV and its metabolite1H-1,2,4-triazole-3-carboxamide (TCA) in rat plasma. Theendogenous interference was overcome by use of ribavirin-13C5as the internal standard.The pharmacokinetic parameters of RBV when administrated alone or in combinationwith silymarin, diammonium glycyrrhizinate, bicyclol or oxymatrine were determined.The results revealed that co-administration of RBV with silymarin, diammoniumglycyrrhizinate or bicyclol resulted in decrease of AUC of RBV, while co-administrationof RBV with silymarin or bicyclol resulted in increasing of Vd and decreasing of Cmaxof RBV.ConclusionThere is significant drug interaction between diammonium glycyrrhizinate, silymarin,glycyrrhizin or bicyclol and RBV. Silymarin was effective to protect the HepG2cells againstRBV induced cytotoxicity. Co-administration of silymarin, diammonium glycyrrhizinate,bicyclol or oxymatrine with ribavirin (180mg/kg) results decrease of the mortality. Silymarinand bicyclol can significantly antagonize the reduction of WBC; Silymarin, diammoniumglycyrrhizinate, bicyclol or oxymatrine can reverse the increase of PLT induced by RBV.Co-administration of silymarin and bicyclol with RBV resulted in decreasing of AUC andCmax of both RBV and its metabolite TCA, thus their effects on the anti-HCV effects ofRBV needs further investigation. PART TWO：Experimental research on liver targeted ribavirin against HCVObjectTo investigate the pharmacokinetics of liver targeted ribavirin.Methods1． The pharmacokinetics of liver targeted ribavirin conjugates in rat after oraladministration was investigated.2. Effect of cholic acid on the pharmacokinetics of RBV-Leu-CA in rat after oraladministration was investigated.Results1. The oral bioavailability of ribavirin after oral administration of bile acid-ribavirinconjugate with leucine as a linker was equal to that of RBV.2. Co-administration of cholic acid with RBV-Leu-CA results in reduction of AUC andCmax of ribavirin in rat blood.ConclusionThe oral bioavailability of the bile acid targeted conjugate with leucine as a linker wasthe highest and co-administration of cholic acid significantly antagonized the absorption ifRBV-Leu-CA, indicating that the targeted conjugates were delivered into the liver via thebile acid mediated transportation system route.