| Summary: | 碩士 === 國防醫學院 === 藥學研究所 === 87 === The biodegradable polylactide (PLA) and PLA copolymers have been extensively investigated as drug carriers because they have been shown not to cause adverse tissue reaction. In addition, the degradation of this hydrophobic polymer could continue for one to two years. In 1990, Deng and Viong synthesized the PLLA/PEG copolymer to increase the PLA degradation rate by introducing hydrophilic PEG into the PLA chain. Many studies on PLLA/PEG copolymer’s degradation mechanism, protein binding and application on controlled drug delivery systems have been investigated and all data indicate that it is a potential drug carrier because of the PLLA/PEG copolymer is nontoxic, biodegradable and biocompatible.
In this study, PLLA/PEG copolymer with molecule weight ranging from 3000 to 26000 have been prepared and characterized. Vancomycin hydrochloride is encapsulated into PLLA/PEG copolymer to form the microspheres by coacervation and multiple emulsion method, respectively. The formulation with different polymer molecule weight, drug loading (%), and the ratio of dispersed phase/continuous phase volume were studied in order to investigate the effects of factors on the particles size of microspheres and drug release rate from microspheres. The optimum formulation of mirospheres which could release vancomycin hydrochloride for 14 days have the following compositions: low molecule weight of polymer (mol.wt.3787), 3% lecithin as emulsifiers, and drug loading as 25%. In order to decrease the initial burst effect of the microspheres in the dissolution test, microspheres were dispersed in melted PEG 4000 polymer to melt-coated the microspheres to form a cylinder matrix, and avoid the initial burst effect. Further animal studies need to be conducted in order to evaluate the release rate of microspheres in vivo. In the future, we hope that these implantable controlled release delivery systems could be clinically applied for the treatment of osyeomyelitis.
|
|---|
