| abstract |
A sustained release composition comprising an active substance, a hydroxynaphthoic acid, a lactic acid-glycolic acid polymer; wherein the weight average molecular weight of said lactic acid-glycolic acid polymer based on the amount (micromoles) of the terminal carboxyl group per unit mass (grams) of said lactic acid-glycolic acid polymer is 1,200,000-3,000,000. Said composition provides for a composition having the active substance at a high concentration while suppressing excessive initial release, thus giving a stable releasing rate. |