Effect of drying on extruded pellets based on kappa-carrageenan.

kappa-Carrageenan is a new pelletisation aid for the wet extrusion/spheronisation process. Its promising behavior during pelletisation offers a potential replacement of the commonly used microcrystalline cellulose in several formulations. Due to its high water binding, the drying step of the pelletisation has gained increasing attention. Therefore, a systematic investigation of the effect of drying conditions on pellet properties was the aim of this study. Pellets with different formulations were dried in fluid bed, circulation-, and vacuum oven and then characterized by mean dissolution time, tensile strength and disintegration time. Increasing the temperature and duration of the drying process decreased the mean dissolution time, tensile strength and disintegration time of the pellets. The observed effects were attributed to a cautious decomposition of the kappa-carrageenan above 70 degrees C. Furthermore an ionic interaction between calcium ions of dicalciumphosphate and sulfate ester groups of kappa-carrageenan affected the pellet properties like drug release.