| 초록 |
The bovine insulin microcrystals, instead of insulin solutions were encapsulated within poly (latide-co-glycolide) (PLGA 50:50) by the multiple emulsion-solvent evaporation technique and compared with insulin liquid core (solution) microcapsules in terms of encapsulation efficiency, drug content and stability of insulin during release. The encapsulation efficiency of insulin microcrystals was maintained constant at about 76% regardless of the insulin loading in the system (10-50 mg/ml), while that of insulin solution decreased from 73% to 42% with increase in the insulin loading. At the low insulin loading in the system, both insulin-solution-loaded microcapsules (1.11±0.15%) and insulin crystal-loaded microcapsules (1.06±0.26%) showed almost equal drug content. As the insulin loading increased, the drug content of both liquid core and microcrystal core increased. The crystal-loaded microcapsules, however, showed much higher drug content than the solution-loaded microcapsules. At 50 mg/ml insulin loading, the drug content of the crystal-loaded microcapsules and the solution-loaded microcapsules was 5.84±0.74%, 3.31±0.67%, respectively. To evaluate the stability of insulin desamido products in the insulin released was determined with reverse phase-HPLC. The amount of deamido products released from the crystal-loaded micsocapsules (1.26±0.20%) was much lower than that of solution-loaded microcapsules (6.83±0.64%). At the pH of insulin isoelectric point, insulin-microcrystal-loaded microcapsules could be stored in liquid suspension.
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