Microcapsules with a soybean lecithin coat as a short-term controlled release dosage form were successfully prepared using the Wurster process. Each of them was composed of a lactose core of 75-106 μm, a drug-layer of carbazochrome sodium sulfonate (CCSS, a model drug), soybean lecithin (SL), cholesterol (CH), stearic acid (SA) and polyvinylpyrrolidone (PVP) and a coat of SL, CH, SA and PVP. Their release properties were evaluated at 37°C in a 0.9% saline solution by a column method. When the coat lacked either or both CH and SA, the microcapsules showed rapid burst in CCSS release. However, the release of CCSS exhibited a short-term delayed and subsequently prolonged profile when the coat was composed of all of four components; the lag time and the subsequent release rate were sensitive to the composition of coat and the coating level. As a dosage form with a short-term controlled release property, the microcapsules more than 100% coated with a SL-CH-SA mixture of 5 : 5 : 2 weight ratio and 42% PVP based on this mixture were found.
