PROBLEM TO BE SOLVED: To provide a bioabsorbable release-sustaining pharmaceutical formulation using a biodegradable release-sustaining base material which can prevent an effective component drug from being released too rapidly just after administration of the formulation and then allow continued release of the drug for at least one month at a defined rate.SOLUTION: For the biodegradable release-sustaining base material, a lactic acid-glycolic acid copolymer (PLGA) with an adjusted distribution in molecular weight is used. Specifically, the pharmaceutical formulation comprises the drug and the lactic acid-glycolic acid copolymer which has following fraction contents for their respective molecular weights determined by gel-permeation chromatography: a fraction content of less than 5 w/w% for a molecular weight of 40,000 or more, a fraction content of less than 20 w/w% for a molecular weight of 16,000 or more and less than 40, 000, a fraction content of 45 w/w% or more for a molecular weight of 5,000 or more and less than 16,000, a fraction content of less than 10 w/w% for a molecular weight of 2,000 or more and less than 4,000, and a fraction content of 5 w/w% or more for a molecular weight of 500 or more and less than 1,500.COPYRIGHT: (C)2007,JPO&INPIT【課題】医薬品製剤において、製剤投与後に有効成分である薬物の急激な初期放出が抑制され、かつ1ヶ月間定められた速度で薬物が放出される生体内分解性徐放性基材を用いた生体吸収性徐法性医薬製剤を提供することを課題とする。【解決手段】生体内分解性徐放性基材として、分子量分布を調節した乳酸-グリコール酸共重合体(PLGA)を用いることによる。具体的には、乳酸-グリコール酸の共重合体であって、ゲル浸透クロマトグラフィー法により求めた分子量画分が、分子量40,000以上が5w/w%未満、分子量16,000以上40,000未満が20w/w%未満、分子量5,000以上16,000未満が45w/w%以上、分子量2,000以上4,000未満が10w/w%未満、分子量500以上1,500未満が5w/w%以上、である乳酸-グリコール酸共重合体に薬物を含有させた医薬製剤による。
