Controlled release-drug delivery system for oral administration

PURPOSE: Provided is a sustained release drug delivery system which sustains drug-releases effectively in the gastrointestinal tract and controls drug-release time. The system involves no orifice forming which occurs in the tablet and exhibits zero-order release of pharmaceutically active ingredients. CONSTITUTION: The sustained release drug delivery system is characteristically composed of: a crystalline nucleated material; a water absorption promoting layer which is formed on the outer surface of the crystalline nucleated material; a pharmaceutically active ingredient containing layer which is formed on the outer surface of the water absorption promoting layer; and a multiporous layer which is formed on the outer surface of the pharmaceutically active ingredient containing layer.