Preparation And Pharmacodynamics Evaluation Of Triptolide Self-Microemulsifying Drug Delivery Systems

Triptolide alcohol,also known as triptolide,is an epoxyditerpene lactone compound isolated from Tripterygium wilfordii,Tripterygium hypoglaucum and Tripterygium wilfordii.It has low water solubility,low bioavailability in vivo,high gastrointestinal irritation and poor patient compliance.Triptolide Self-microemulsifying Drug Delivery Systems can improve the poor water solubility and reduce toxicity on the basis of maintaining its anticancer activity,and provide a theoretical basis for expanding the clinical application of triptolide and the development of anticancer drugs.The main research contents,methods and results are as follows:(1)By comparing the solubility of triptolide in different oil phases,surfactants and cosurfactants,the oil phase and mixed surfactant of self-emulsifying drug release system were screened.Medium chain triglyceride was as the oil phase,polyoxyethylene castor oil,Tween-20 were as surfactants,and polyethylene glycol 400 was as the cosurfactant.The basic prescription of TP-SMEDDS was preliminarily determined by drawing pseudo-ternary phase diagram:polyoxyethylene castor oil was determined as surfactant.The evaluating indicators were including self-microemulsifying time,appearance,particle size and drug content of the microemulsion.The prescription technology of TP-SMEDDS was optimized by central composite design-response surface analysis based on 2 factors and 5 levels.The final prescription technology was as follows:oil phase mass ratio was 25.3%,surfactant mass ratio was 49.6%,cosurfactant mass ratio was 25.1%,theoretical particle size was 31.168 nm,theoretical drug content was 2.981 mg/g.The optimized prescription verification accords with the prediction result.(2)Evaluate the appearance,morphology,particle size and drug content of TP-SMEDDS prepared by the optimized formulation and process.An in vitro analytical method for the determination of triptolide self emulsifying content was established.The results showed that the prepared TP-SMEDDS was spherical,uniform in size,uniform in distribution and no adhesion under transmission electron microscope;the particle size of TP-SMEDDS was less than 50 nm determined by laser particle size analyzer;the in vitro release test showed that the TP-SMEDDS was completely released in the medium of pH 7.4 PBS for 6 h.The release curves of lactones self microemulsion solution are in accordance with the First-order equation model.The results showed that the self microemulsion drug delivery system could improve the dissolution and dissolution rate of triptolide.(3)Nude mice bearing human gastric cancer cell line MGC80-3 were divided into blank excipient group,TP-SMEDDS high-dose,medium-dose and low-dose group and TP raw material high-dose,medium-dose and low-dose group.The in vivo anti-tumor activity of TP-SMEDDS was evaluated by comparing the body mass,tumor volume,weight,tumor inhibition rate and tumor delayed growth time of each group.The results of pharmacodynamics experiment showed that TP had obvious antitumor effect compared with the blank excipient group;TP-SMEDDS could significantly inhibit the growth of transplanted tumor compared with the TP raw material group;the volume of transplanted tumor in the 0.6mg/kg TP-SMEDDS group(117.5±76.54mm3)was significantly lower than that in the blank excipient group(438.1±192.4mm3)after administration.The tumor inhibition rate reached 47.06%,which was significantly higher than that of the TP raw material group(41.18%)at the same dose.The results showed that the self microemulsion drug delivery system could improve the antitumor effect of triptolide in vivo.(4)The level of ALT,AST,Urea,Scr,TP,ALB,GLOB and UA in serum were determined.The animals were weighed and the liver and kidney were also collected.The appearance and morphology of the liver and kidney were observed by the biological microscope,and the liver and kidney index were calculated.Compared with free TP group,the level of AST and ALT in TP-SMEDDS group was significantly declined(P<0.01),TP level was increased significantly(P<0.05),and A/G was also significantly rose(P<0.01).Scr level showed a slightly decrease.Urea and UA level were decreased significantly(P<0.05 and<0.01,respectively).In TP-SMEDDS group,liver cells were slightly swollen and a few inflammatory cells were found in liver tissue.In TP group,some steatosis and fragmentation necrosis were showed in liver tissue.The hepatocyte nucleus obviously enlarged,and a large number of fibrous tissue was found.There were no obvious abnormal pathological features in renal tissue of both groups,compared to that in saline groups.The TP-SMEDDS presented a significantly decrease of hepatotoxicity and renal toxicity compared to free triptolide.CONCLUSION:The triptolide self-microemulsifying drug delivery systems has the advantages of small particle size,uniform distribution,high drug content and simple preparation method.The experimental results in nude mice showed that the self-emulsifying system could effectively improve the oral bioavailability of triptolide and decrease the hepatorenal toxicity of triptolide.In summary,this dosage form can be a new way to expand the range of clinical application of triptolide.