Study On BCNU-loaded PLA Carrier

BCNU, relatively high lipid solubility and low molecular weight, is widely used for the treatment of malignant gliomas. However, BCNU is limited by its systemic toxicity and characteristic, such as its water-insolution and short half life. In order to solve these problems, the following work has been done in this dissertation.PLA-BCNU microspheres(MPs) were prepared by Solvent evaporation process via using PLA as the polymer matrix. Through SEM(Scanning electronic microscope) micrograph, the microspheres sizes and standard deviation were effected by molecular weight and oil-phase distribution models. Smooth surface without cavities or crystal of the drug could be get in this dissertation. Colorimetric method was used to determinate drug loaded ratio and drug encapsulation efficiency of MPs, and they could reach 15% and 40%, respectively. BCNU dispersion and stability in the MPs was studied by DSC(Differential scanning calorimetry analyses).The in vitro release experiments studied the effects of molecular weight of PLA, drug content in MPs and MPs sizes on release behavior of microspheres. The release BCNU microspheres was slow(>70day) and stable, and could be described as square root-time process. Improve the surfaces of MPs could weaken their degree of burst release. Some degradation of MPs after releasing for 1 month could be seen by SEM. The basic sphericity was remained but with some cavities which were the channels for BCNU when delivered into the environment.Addition of PEG to PLA film can improve release behavior of PLA-BCNU carrier by increasing the speed of drug release.