Controlled-release tablets exhibiting excellent storage stability are achieved by granulating a pharmaceutically active agent with a hydroxyalkylcelluose, blending the resulting granules with an extragranular phase composed of a particulate material that provides a sustained-release matrix, and compressing the blend into a tablet form, which may be optionally coated, such as with an enteric coating composition, to provide delayed release and/or to enhance stability of the active agent.