The present invention addresses the problem of providing a pharmaceutical preparation, i.e., a pharmaceutical preparation composition, which contains a polymerized camptothecin derivative comprising a polymer carrier and a camptothecin derivative bonded to the polymer carrier and capable of associating in an aqueous solution to exhibit a nano-particle formation property, and which has improved pharmaceutical stability. Particularly, the present invention addresses the problem of providing a pharmaceutical preparation which has an excellent associative aggregation formation property that is an important factor and also has excellent storage stability in terms of chemical stability. A pharmaceutical preparation containing a block copolymer comprising a polyethylene glycol segment and a poly(glutamic acid) segment linked to each other, wherein the poly(glutamic acid) segment contains a glutamic acid unit having a camptothecin derivative bonded thereto； and a pharmaceutical preparation containing at least one additive selected from the group consisting of arginine, histidine and sodium chloride.本發明之課題在於提供一種醫藥製劑組合物，其係含有於水溶液中締合而具有奈米粒子形成性之使喜樹鹼衍生物鍵結於高分子載體而成之高分子化喜樹鹼衍生物之醫藥製劑，且製劑穩定性得到提高。本發明之課題尤其在於提供一種具有作為重要因素之締合性凝聚體形成性與化學穩定性優異之保存穩定性之醫藥製劑。 本發明之醫藥製劑含有聚乙二醇鏈段與包含鍵結有喜樹鹼衍生物之麩胺酸單元之聚麩胺酸鏈段連結而成之嵌段共聚物，且含有選自由精胺酸、組胺酸及氯化鈉所組成之群中之一種以上之添加劑。
