The present invention relates to a solid pharmaceutical composition comprising (a) at least one drug selected from donepezil or a pharmaceutically acceptable salt or solvate thereof and (b) at least one matrix former which is selected from the group consisting of cellulose derivatives, starch derivatives and mixtures thereof, wherein the matrix former has a viscosity of 80 to 120,000 mPa·s, determined for a 2 % (w/v) aqueous solution at 20°C, as well as a process for its preparation.
