the present invention includes a tablet core containing a drug (or drugs active ingredient) and the chamber structure forming material and coating the above tablets cores, and a coating layer provided with the drug discharge hole, when the aforementioned drug osmotic pump formulation releases the drug in water or an aqueous medium, the fine in the aforementioned chamber structure forming material coating layer in the to form a chamber structure, and the total volume Vb of the above-mentioned micro-chamber structure is increased according to the release time, and the release of R of the above-mentioned drug active ingredient (or release the amount of A) is to provide a drug osmotic pump formulation which is directly proportional to Vb . Osmotic pump formulations of the present invention is suitable for the controlled release of readily water-soluble drugs and poorly water-soluble drugs, particularly low solubility drugs or pH-dependent drug.本発明は、薬物(または薬物活性成分)およびチャンバー構造形成材料を含有する錠コアと、前述錠コアをコーティングし、薬物放出孔が設けられたコーティング膜とを含み、前述薬物浸透圧ポンプ製剤が水または水性媒体において薬物を放出する時、前述チャンバー構造形成材料がコーティング膜内で微細チャンバー構造を形成させ、かつ前述微細チャンバー構造の合計体積Vbが放出時間に従って増大し、かつ前述薬物活性成分の放出度R(または放出量A)がVbに正比例する薬物浸透圧ポンプ製剤を提供する。本発明の浸透圧ポンプ製剤は、水易溶性薬物および水難溶性薬物、特に低溶解性薬物またはpH依存性薬物の放出制御に適する。
