Novel polysaccharide derivatives and dosage forms

Polysaccharide derivatives having a median Equivalent Projected Circle Diameter (EQPC) of less than 140 micrometers and a particle size and shape distribution meeting condition A or B or both are useful for preparing dosage forms, particularly for preparing compressed sustained-release dosage forms: A. non-compacted polysaccharide derivative particles have a flowability of at least 45 g/sec through a vertically inverted cone having a vertex angle of about 40 and an outlet diameter of about 50 mm, or B. i) no more than 40 volume percent of the polysaccharide derivative particles are fine particles having a particle length LEFI of less than 40 micrometers and ii) no more than 40 volume percent of the polysaccharide derivative particles are fibrous particles, and the sum of the fine particles and the fibrous particles does not exceed 50 volume percent.