Poorly water-soluble drugs 50μg / ml or less, the following formula solubility in water (1): (Wherein, n: m to 0.25: 0.75 to 0.95: in the range of 0.05, R represents an alkyl group which may have a substituent, 1, R 2 R is represents a methyl group or a hydrogen atom, a water-soluble copolymer having a repeating unit represented by.) that represents a methyl group, and, Me represents a poorly water-soluble drug-containing water-miscible solution containing a water-miscible solvent, Pharmaceutical compositions average particle diameter obtained by mixing, with water containing a drug-containing nanoparticles 10~150nm well as oral preparations containing the pharmaceutical composition.水への溶解性が50μg/ml以下の難水溶性薬剤、下記一般式(1):(式中、n:mは0.25:0.75~0.95:0.05の範囲内であり、Rは置換基を有してもよいアルキル基を表し、R1,R2はそれぞれ水素原子またはメチル基を表し、Meはメチル基を表す。)で示される繰り返し単位を有する水溶性共重合体、及び、水混和性溶剤、を含む難水溶性薬剤含有水混和性溶液と、水と、を混合することにより得られる平均粒径が10~150nmの薬剤含有ナノ粒子を含有する医薬用組成物;並びに、本医薬用組成物を含有する経口投与製剤。
