A pharmaceutical composition for modified release,comprising (1) (R)-2-(2-aminothiazol-4-yl)-4'-[2-[(2-hydroxy-2-phenylethyl)amino]ethyl]acetic acid anilide, or apharmaceutically acceptable salt thereof, (2) at least oneadditive which ensures penetration of water into thepharmaceutical composition and which has a solubility suchthat the volume of water required for dissolving 1 g of theadditive is 10 mL or less, and (3) a hydrogel-formingpolymer having an average molecular weight of approximately100,000 or more, or a viscosity of 12 mPa.cndot.s or more at a 5%aqueous solution at 25°C is disclosed.
