Studies On The Preparation And Effect Of The Lipidic Solid Dispersion Of Norcantharidin Microspheres For Transcatheter Arterial Chemoembolization

Objective:To prepare the lipidic solid dispersion of Norcantharidin loading alginate / chitosan Microspheres(LSD/NTCD-ACM) for transcatheter arterial chemoembolization (TACE)by using alginate and chitosan as carriers and lipidic solid dispersion of Norcantharidin(LSD/NCTD)as model medicine. Chemotherapeutic agents were selectively injected into tumor vessel to evaluate its effects for transarterial hepatic chemoembolization (TACE) in an animal model of liver cancer (VX2).And to provide reference for clinical treatment of unresectalbe liver cancer.Method: (1) The LSD/NTCD-ACM was prepared through the emulsification- gelation method. Single factor design were practiced on the ratio of ALG/CS,order of preparation,temperature, emulsifier amount, kind of solid lipid and the ratio of it to NCTD,orthogonal design were based on drug loading content,encapsulated efficiency and unreleased rate in a week with Calcium chloride concentration,ratio of LSD/NTCD/carrier ,ratio of drug/solid lipid as index. (2)The surface characterization of the microspheres was identified with scanning electronic microscope (SEM). Application of infrared spectroscopy (FT-IR), X-ray powder diffraction (X-RD) and differential scanning calorimetry (DSC) to verify the formulation of LSD/NTCD-ACM. Then the micromeritic characteristies, suspensibilit, fluidity and catheter bolus were considerated. (3) The in vitro released profile of NCTD in different dosage form and LSD/NTCD-ACM in different diametres were investigated with Dynamic dialysis method in pH 7.4 phosphate buffer solution (PBS) and the stability of microspheres was studied. (4) New Zealand rabbits were selected as model, VX-2 tumor tissue was embeded in the left lobe of liver in laparotomy method, puncture needle method and biopsy needle method respectively . Ultrasound and CT examinations were performed at different time periods after implantation respectively. (5) 24 male New Zealand white rabbits were randomly divided into four groups with 6 rabbits assigned to each group.The tumors were allowed to grow for weeks, and studies were performed until the volume of the tumors detected by ultrasonograph reached 2–3 cm3. Under anesthesia, transcatheter hepatic arterial embolization was performed and LSD/NTCD- ACM (60-125μm), LSD/NTCD-ACM(125-200μm) or NCTD solution was injected into the hepatic arteries of animals in the three treatment groups and the left one is control group(with no treatment).Before and at 3,7,14 days after injection, the volume of the tumor was measured by ultrasonograph, the serum of all rabbits was collected, and the level of aspartate aminotransferase (AST) was checked. During the last course of their disease, the rabbits were given analgesics to relieve suffering. The survival period of the three groups of rabbits after treatment was recorded, and degree of liver cell necrosis was also assessed on the histopathological specimens.Results: (1) Single factor design shown that the ratio of ALG/CS,order of preparation,temperature, emulsifier amount mainly affected the shape of MS while kind of solid lipid and the ratio of it to NCTD mainly affected the release profile. The loading drug content, encapsulated efficiency unreleased rate in a week of the microspheres of the choosen prescription was 9.46%, 87.31% and 39.5% respectively(2) SEM graph shows that microparticles were sphere, smooth, uniform and less of adhere. FT-IR,X-Rd and DSC graph indicated the reaction between CS and ALG, and NCTD dispersed in gelskeleton. The micromeritic characteristies, suspensibilit, fluidity and catheter bolus were suitable. (3)The release profile of LSD/NTCD-ACM followed Weibull distribution in vitro and sustained for 15-20d. The larger the particle size was the slower NCTD released. (4) The study showed tumor grew productivly during 2～4 weeks after inoculation and tumor's body increased rapidly. 4 weeks later degeneration and necrosis at the center of tumor can be seen, peripheral lymph node lung metastasis were aslo be seen. Laparotomy had greater damage to rabbit and tumor tissue easily dropped into enterocoelia in puncture needle method. To synthetic compare, biopsy needle method under ultrasonic guidance was employed. (5) After treatment, every 3, 7 and 14days, to evaluate the volume and growth rates of tumor with ultrasound: by measuring the diameter.The tumor growth rate in LSD/NCTD-ACM(60-125/μm) group and in LSD/N CTD-ACM(125-200/μm) group was significantly decreased compared to that in control group and in NCTD group (P < 0.05). The survival period and life prolonging rate in LSD/NCTD-ACM(60-120/μm) group and LSD/NCTD-ACM(120-200/μm) group was significantly longer than that in both control group(P<0.05) and NCTD group (P<0.05). There was an increase (P < 0.05) in the serum AST level in the three treated group at the first day after injection when compared to the control group. And the serum AST level in the two embolization groups were higher than that in the NCTD group (P < 0.05), however, no significant difference was observed between the two groups at the first day after injection (P > 0.05). Liquefaction necrosis and coagulation necrosis were both observered in the two embolization groups.Conclusion: The prepared LSD/NCTD-ACM have a satisfactory sustained release profile due to the preparation of LSD/NCTD, a high drug loading and entrapment efficiency, a smooth surface and round in shape, the suspension and dispersion of it were also fit. The results of pharmacodynamic study shown that LSD/NCTD-ACM are potential candidates for embolization of liver cancer and the side effect were reasonable and controllable.