Fluidity parameters (angle of repose, fluidity index K, coefficient of internal friction, cohesive force, and flow rate) of pharmaceutical powders with various mixing ratios of two components and three components of powders were measured in order to investigate the possibility of estimating and evaluating the fluidity of mixed powders. Changes in the pattern of the mixing ratio and fluidity depended on whether corn starch was included or not in the mixed powders, and fluidity index K of mixed powders including corn starch showed a minimum value at the mixing ratio of corn starch of 60%. Relation between fluidity index K and mixing ratio of mixed powders excluding corn starch showed nearly a straight line. This study showed that, if the fluidity index K of each pharmaceutical powders was known, there would be a possibility of estimating the fluidity of multi-component mixed powders.
