Physicochemical properties and controlled drug release of microcapsules prepared by simple coacervation.

Ternary phase diagrams of gelatin-water-methanol, gelatin-water-ethanol, and gelatin-water-propanol systems were prepared to evaluate optimal coacervation. The results of their evaluation suggested that the optimal coacervation region expands with the hydrophobicity of the added poor solvent (methanol, ethanol, 1-propanol, and 2-propanol). Microcapsules prepared based on the optimal coacervation region differed in controlled drug release among poor solvents used even when the concentration of gelatin, a membrane component, is the same. Compared with microcapsules prepared using the gelatin-water-ethanol system, those prepared using the gelatin-water-propanol system showed a 34% decrease in the drug release rate 24h after the initiation of the drug release test. These results suggested that microcapsules prepared using gelatin-water-various lower alcohol systems can readily control drug release and can be a useful drug delivery system (DDS).