Controlled release composition comprising lactic acid polymer and hydroxynaphthoic acid, and method of producing the same

Controlled release composition containing a physiologically active substance in a high content, suppresses the initial release in excess, and achieves a stable release rate over a long period. A controlled release composition comprising: (1) a physiologically active substance or a salt thereof in an amount of about 14% (w / w) to about 24% (w / w) based on the total weight of the composition, (2) hydroxynaphthoic acid selected from the group consisting of 3-hydroxy-2-naphthoic acid and 1-hydroxy-2-naphthoic acid or salt thereof, and (3) a lactic acid polymer or a salt thereof having a molec weight average weight ular 15,000 to 50,000, wherein the content of polymers having molecular weights of 5000 or less is approximately 5% by weight or less, where the molar ratio of said hydroxynaphthoic acid or a salt thereof with respect to said physiologically active substance or a salt thereof It is from 3: 4 to 4: 3. A method for producing said controlled release composition comprising the removal of a solvent from a mixed solution of a physiologically active substance or salt thereof, and a lactic acid polymer or a salt thereof having a weight average molecular weight. 15,000 to 50,000, where the content of polymers having molecular weights of 5000 or less is of the order of 5% by weight or less. A medicament comprising said controlled release composition.