A pharmaceutical modified release formulation comprising a pharmacologically active substance and a modified water-soluble polysaccharide, which modified water-soluble polysaccharide is obtainable by: a) forming a precipitate of a water-soluble polysaccharide by contacting a solution of the water-soluble polysaccharide with a solvent in which the polysaccharide is poorly soluble or insoluble; or b) milling a water-soluble polysaccharide. The modified water-soluble polysaccharides provide modified release formulations with high tablet hardness. Also claimed are a process for preparing the modified release formulation, and the use of the modified water-soluble polysaccharides as an excipient in a pharmaceutical formulation.