A controlled-release pharmaceutical composition including first and second groups of microparticles, each of the microparticles including a core including
tamsulosin or pharmaceutically acceptable salts thereof, a controlled-release
polymer coating layer formed on the core, and an enteric
polymer outer layer formed on the controlled-release
polymer coating layer, wherein the average thickness of the controlled-release
polymer coating layer is different in each of the first and second groups of microparticles, and an oral formulation including the same, are provided. This pharmaceutical composition can easily control the extent of release of an
active ingredient depending on changes in pH in the intestinal tract and the
release pattern of the
active ingredient in the
small intestine, thus preventing the
active ingredient from being rapidly transferred into the blood to thereby minimize side-effects, and maintaining the effective
blood concentration of the active ingredient for a predetermined period of time. Furthermore, this composition can shield the
bitter taste of the active ingredient even when exposed to the inside of the mouth, thus increasing the therapeutic effects for patients upon
oral administration.