The Study Of Drug Delivery For Bulleyaconitine A-multivesicular Liposome And Bulleyaconitine A/DSPE-PEG2000 Micelle

Bulleyaconitine A （BLA） is a diester-diterpene type alkaloid extracted from Aconitum plant. It is an excellent analgesic and anti-inflammatory agent and can be used for the treatment of rheumatoid arthritis, osteoarthritis, Periarthritis humeroscapularis, lumbar muscle strain, sprain and terminal cancer pain etc. After intramuscular injection of BLA, there is severe irritant at the injection site, which causes bad compliance. In this paper, the basic physicochemical properties of BLA were investigated. BLA multi-vesicular liposomes （BLA-MVL） and BLA/DSPE-PEG₂₀₀₀ micelles were prepared, their characters in vitro were studied, and their pharmacodynamics was evaluated.A RP-HPLC method was established to analysis BLA in vitro. The solubility of BLA in various PBS buffer, normal saline and purified water were determined by thermostatic vibration method at 37°C. The apparent oil/water partition coefficients of BLA between n-octyl alcohol and PBS of various pH were determined. It was found that the degradation of BLA in solution was pseudo first-order kinetics, and the pH values, temperatures and ionic strengths had significant effect on the degradation of BLA.BLA-MVL was prepared by double emulsion method and the entrapment efficiency （EE） was determined by low-speed centrifugation method. The effect of some factors, such as the preparation processes, the composition of internal water phase and oil phase on the EEs were studied. The average EE prepared by three batches was 20.1%.BLA/DSPE-PEG₂₀₀₀ micelle was prepared by thin-film dispersion method and the mean particle diameter of the globular micelle particles was below 20nm. Ultrafiltration method was established for determining EE of BLA/DSPE-PEG ₂₀₀₀ micelle. The effect of OA contents, drug to lipid ratios, hydration media, and PC contents on the properties of resulted micelles were investigated. The entrapment efficiencies of optimized micelle were higher than 50%. Freezing drying method was used to obtain product with good appearance and re-dispersibility. The degradation of BLA was obviously slowed down by entrapping into micelles. The release of BLA/DSPE-PEG ₂₀₀₀ micelle in vitro was carried out with dialysis method. The results showed that there was a initial burst release due to the free drug at first, after that the encapsulate BLA released from micelle slowly.BLA-saline solution, BLA-MVL suspension and BLA/DSPE-PEG₂₀₀₀ micelle solution were intramuscularly injected in rabbit, and the results indicated that BLA-saline solution had obvious muscular irritant, BLA-MVL suspension and BLA/DSPE-PEG₂₀₀₀ micelle had no obvious muscular irritant. Hot-plate and formaldehyde-induced pain test in mice showed that all these three preparations have periphery and center analgesia effect. Compared with BLA-saline solution, BLA-MVL suspension and BLA/DSPE-PEG₂₀₀₀ micelle solution could reduce the irritation of the injection site and prolong the drug action period.