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摘要
The objective of this study was to develop an isopropyl formate-based evaporation process useful in producing poly-D, L-lactide-co-glycolide microspheres. Surprisingly, the evaporating tendency of isopropyl formate was comparable to that of methylene chloride and far better than that of ethyl acetate. After optimization of the isopropyl formate-based process, progesterone was encapsulated into microspheres. Under our conditions, its encapsulation efficiency ranged from 75.1% to 92.6%. Even though all microspheres took spherical geometry, their external and internal morphologies were greatly influenced by progesterone payloads. A GC analysis demonstrated that residual isopropyl formate in various microspheres was 1.8% to 4.0%. Interestingly, progesterone underwent polymorphic transition during the micro-encapsulation process - the beta form was present in microspheres with lower progesterone payloads, whereas the alpha form predominated over the beta one at higher progesterone loads. In terms of human safety and environmental toxicity, isopropyl formate might have an edge over halogenated organic solvents for solvent evaporation.
- 出版日期2011
