An enhanced process for encapsulating aspirin in ethyl cellulose microcapsules by solvent evaporation in an O/W emulsion

An enhanced process for microencapsulating aspirin in ethylcellulose was de monstrated using an oil-in-water emulsification/solvent evaporation techniq ue. Methylene chloride (CH2Cl2) was used as the dispersed medium and water as the dispersing medium. The recovered weight, particle size distribution, aspirin loading efficiency, and the aspirin release rate of microcapsules were analysed. The addition of appropriate amounts of non-solvent (n-heptan e) prior to the emulsification increases the recovered weight, but decrease s the size of the formed microcapsules. The addition of non-solvent also ch anges the microcapsule characteristics, resulting in a coarser surface and an increased release rate. Increasing the polymer (ethylcellulose) concentr ation in the dispersed phase increases the size of the microcapsules, the r ecovered weight, and loading efficiency, but decreases the release rate. Th e release rate follows first-order kinetics during the first 12 h, suggesti ng a monolithic system with aspirin uniformly distributed in the microcapsu le.