Studies On Norcantharidin-Loaded Solid Lipid Nanoparticles

Solid lipid Nanoparticles (SLN) were solid colloidal systems with natural or synthetic lipid as drug carrier. They were novel and promising drug delivery systems, which could be used for topical, oral and parenteral administration, advantages of ideal targeting effects, low drug leakage, good physical stability and low toxicity. The objective of the thesis was to investigate Norcantharidin-loaded solid lipid nanoparticles (NCTD-SLN) for intravenous administration. Firstly, the method of ultracentrifugation was used to separate SLN and free drug, then the content and entrapment efficiency of SLN was determined by HPLC. The method of membrane-ultrasonic decentralization at low temperature was employed to prepare NCTD-SLN, with stearic acid as lipid carrier. Such investigation had no report in China.The optimal formulation was obtained by uniform design method, with the entrapment efficiency of NCTD-SLN as the criterion, and the drug-to-lipid ratio, weight of Egg phophatidylcholine , concentration of Poluronic F68, rate of injecting , ultrasonic frequency and oil/water volume ratio as influence factors. The highest entrapment efficiency of 55.4±1.2% was acquired. The NCTD-SLN was prepared for the first time, without any other domestic or foreign report. The physicochemical proprieties investigation showed that the NCTD-SLN prepared was regular and well distributed with a mean diameter of (189±6.00) nm, zeta potential of (-23.15±0.17) mv, pH from 5.4 to 6.0, and drug-loaded capacity of 10.12%. The preliminary stability experiments indicated that the NCTD-SLN suspension could keep stable at 4℃for at least three months, and there were no remarkable changes on the particle size and entrapment efficiency. In addition, the in vitro drug release of NCTD-SLN was investigated in different medium (eg,phosphate buffer, pH6.8), and the result all tally with bioexponential equation. The formation of NCTD-SLN was validated by DTA difraction, which indicated that it was absolutely different from the simple mixture of its components. The method of HPLC was established to determine Norcantharidin in mice serum and tissues with steady recovery, high sensitivity, accurateness and good reproducibility, which was suitable for the analysis of bio-samples in batches. After iv administration of Norcantharidin solution and NCTD-SLN to mice, the drug concentrations in serum and different tissues were determined by HPLC, and the pharmacokinetic progresses in the mice for two preparations were brought into comparison, which showed they were both fitted to two-compartment model. AUCo-24 were 10121.3 and 16102.4(ng/ml)·h ; Vd were 10.12 and 2.82L/kg; Cl were 0.416 and 0.147L/h/kg; MRT were 5.3 and 10.1h; Eliminative half-life were 4.2 and 9.6h, respectively.The relative uptake rate (r_e) was 1.59 and the targeting efficiency(t_e) was 1.45 and the consideration(C_e) was 1.36.The levels of Norcantharidin in liver were much higher when administrated as SLN, lower in kidney and heart, but no change in serum and lung.