A pharmaceutical composition for modified release comprising (R)-2-(2-aminothiazol-4-yl)-4′-[2-[(2-hydroxy-2-phenylethyl)amino]ethyl]acetic acid anilide or a pharmaceutically acceptable salt thereof, and a carrier for a sustained release pharmaceutical composition, wherein a dissolution rate of the drug from the composition is less than 85% after 30 minutes from the beginning of a dissolution test, is disclosed.
