| Summary: | 碩士 === 國立臺灣大學 === 藥學研究所 === 89 === In the recent two decades, due to new polymers developed and advanced techniques applied in pharmaceutics, microencapsulation of desired drugs for preparation of controlled-release dosage form is being widely investigated. By using controlled-release dosage forms, the dosing frequency is significantly reduced, and the therapeutic effect is also improved. However, the processes of microencapsulation often involve complicated procedures and also need organic solvents to dissolve polymers, which may further cause the contamination of manufacturing environments.
The aim of this study was to explore a simple method of preparing microparticles. Poly(ε-caprolactone) was chosen as the material to encapsulate the model drug, indomethacin, and the hot-melt encapsulation technique was applied because of the low melting point of poly(ε-caprolactone).
Two major advantages of hot-melt encapsulation technique were simple manufacturing process and completely abandoning of organic solvents. By changing types of the external phase and surfactants, adjusting drug initial loading、probe sonicator output power and particle size, the microparticles with a high loading efficiency and a high yield characteristics were obtained.
Surface morphology of microparticles was examined by using a scanning electronic microscopy. The results showed that the surface of microparticles was smooth, non-porous, and possessed spherical shape. No obvious aggregation was observed. According to the weight fraction of microparticles, the particle size mainly distributed in the range of 250~420 μm. Using oil as external phase with surfactant L61, the yield and loading efficiency were 83.18 % and 26.17 %, respectively, but they were increased up to 91.15 % and 91.39 %, respectively, while using water as external phase with surfactant PVA. In addition, high performance liquid chromatography and differential scanning calorimeter analysis data showed that hot-melt encapsulation technique does not influence the stability of indomethacin. In the In vitro release study, the release of indomethacin from larger microparticles ( > 250 μm) was prolonged for 24 hours, and its release profile followed a biphasic release pattern. After coating with chitosan and gelatin, the extent of burst effect and release rate were decreased significantly.
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