| Summary: | 碩士 === 國立中央大學 === 化學工程研究所 === 83 === The preparation of ethylcellulose microcapsules
containingheophylline by using o/w emulsion nonsolvent-addition
phaseeparation method was developed. Dichloromethane-n-hexane
werehosen as solvent-nonsolvent system. The first stage of this
workas to determine the process of drug loss. In the second
stage ofhis work, some methods were proposed to reduce drug
loss. Theharacteristics of microcapsules prepared by these
methods werenvestigated. The results indicated that almost drug
loss happened in fiveinutes after coating solution was poured
into dispersion medium.he drug loss was reduced by increasing
the polymer concentration,y adding nonsolvent in coating
solution, by using mixed solventnd by adding nonsolvent in the
dispersion medium in advance. Theorphology of microcapsules
prepared by these methods was alsonfluenced. Dissolution
studies showed that the release rate ofheophylline from
microcapsules increased with the increase ofolymer
concentration, with the increase of the volume of ddition in
coating solution, with the increase of the volume ofoluene in
mixed solvent and with the increase of the volume ofonsolvent
in advance addition in dispersion medium. However, theelease
behavior of various ethylcellulose microcapsules fittedhe first
order release model and Higuchi matrix release model.
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