ETHYLCELLULOSE TO PREPARE A MATRIX SYSTEM OF A HYDROPHILIC DRUG BY THE MICROENCAPSULATION PROCESS

A hydrophilic drug (potassium chloride) was coated with ethylcellulose by the temperature-induced coacervation method in order to obtain mic rocapsules with retarded drug release. This objective was not achieved even though high polymer contents were used because of crystallizatio n of drug particles on the microcapsular walls. On the other hand, ret arded drug release was obtained by pressing tablets from the microcaps ules due to the formation of a continuous secondary polymer structure, e.g. a matrix-type formulation. Existence of the secondary structure could be confirmed by results of the disintegration test, dissolution test and the microscopic picture of the pressed tablet residue followi ng complete liberation of the drug.