Solid dispersion containing sialic acid derivative

A solid dispersion which comprises a water-soluble macromolecule and a substance dispersed in the water-soluble macromolecule, wherein said substance is selected from the group consisting of a sialic acid derivative represented by the following general formula (I) and a salt thereof, and a hydrate thereof and a solvate thereof:

• [in the above general formula (I), R1 represents a steroid compound residue, R2 represents hydrogen atom or a C1-C4 alkyl group, R3 represents a C1-C15 alkyl group,
• {in the formula, R6 and R1 independently represent hydrogen atom, a halogen atom, a C1-C4 alkyl group, hydroxyl group, R8O— (in the formula, R8 represents a C1-C4 alkyl group, phenyl group or a phenyl-(C1-C3) alkyl group), nitro group, amino group, a C1-C4 alkylamino group, a C2-C8 dialkylamino group or R9O—CO— (in the formula, R9 represents hydrogen atom, a C1-C4 alkyl group, phenyl group or a phenyl-(C1-C3) alkyl group), and symbol “L” represents an integer of from 0 to 6}, R10O(CH2)m— (in the formula, R10 represents hydrogen atom;
• a C1-C4 alkyl group;
• a phenyl group which may have one or more substituents selected from the group consisting of a C1-C4 alkyl group, a halogen atom, hydroxyl group, nitro group, amino group, and a carboxyl group;
• or a phenyl-(C1-C3) alkyl group which may have one or more substituents selected from the group consisting of a C1-C4 alkyl group, a halogen atom, hydroxyl group, nitro group, amino group, and carboxyl group, and symbol “m” represents an integer of from 2 to 6), or (R11)(R12)N—(CH2)n— {in the formula, R11 represents hydrogen atom or a C1-C4 alkyl group, R12 represents hydrogen atom;
• a C1-C4 alkyl group;
• a C2-C7 acyl group;
• a C1-C4 alkylsulfonyl group a phenylsulfonyl group which may have one or more substituents selected from the group consisting of a C1-C4 alkyl group, halogen atom, hydroxyl group, nitro group, amino group, and a carboxyl group;
• or R13O—CO— (in the formula, R13 represents a C1-C4 alkyl group, phenyl group or a phenyl-(C1-C3) alkyl group) and symbol “n” represents an integer of from 2 to 6}, R4 represents hydrogen atom or a C2-C7 acyl group, R5 represents R14O— (in the formula, R14 represents hydrogen atom or a C2-C7 acyl group) or R15NH— {in the formula, R15 represents a C2-C7 acyl group;
• R16O(CH2)p—CO— (in the formula, R16 represents hydrogen atom, a C1-C6 alkyl group, phenyl group, or a phenyl-(C1-C3) alkyl group, and p represents an integer of from 0 to 4);
• a C7-C11 aroyl group which may have one or more substituents selected from the group consisting of a C1-C4 alkyl group, a halogen atom, hydroxyl group, nitro group, amino group, and a carboxyl group;
• a phenyl-(C1-C3) alkylcarbonyl group which may have one or more substituents selected from the group consisting of a C1-C4 alkyl group, a halogen atom, hydroxyl group, nitro group, amino group, and a carboxyl group;
• a C1-C4 alkylsulfonyl group;
• or a phenylsulfonyl group which may have one or more substituents selected from the group consisting of a C1-C4 alkyl group, a halogen atom, hydroxyl group, nitro group, amino group, and a carboxyl group}, and X represents an oxygen atom or a sulfur atom].