APPLICATION OF THE SOLID DISPERSION METHOD TO CONTROLLED RELEASE OF MEDICINE .1. CONTROLLED RELEASE OF WATER-SOLUBLE MEDICINE BY USING SOLID DISPERSION

The release of medicine from solid dispersion which was prepared by evaporation after dessolving or suspending water-soluble medicine into an organic solvent was studied. Oxprenolol hydrochloride was used as a water soluble medicine. Eudragit RS, methylcellulose, ethylcellulos, polyvinylpyrrolidone, hydroxy propyl cellulose and pullulane were used as the polymers. These polymers and oxprenolol hydrochloride were suspended in or dissolved into ethanol under heating, and the ethanol in these solutions was evaporated to solid dispersion. Solid dispersion granules were prepared by grounding and sieving the solid dispersions obtained. The dissolution behavior of oxprenolol hydrochloride was studied by the dissolution test (JP XI). As a result, it was clarified that in a solid dispersion granule composed of 25% oxprenolol hydrochloride, 70% ethycellulose and 5% hydroxypropyl cellulose, the dissolution behavior of oxprenolol hydrochloride from this granule was of a leaching type for the matrix and was not affected by pH. Furthermore, various dissolution behaviors could be obtained by changing the particle size and the ratio of the polymer in the granule. These results suggest that this granulating method by the evaporation of the solvent is useful in preparing a sustained release preparation.