Abstract: A pyridonecarboxylic acid derivative or a salt thereof is represented by Formula (1), where R1 is hydrogen, a halogen atom, a lower alkyl group, or an amino group; R2 is —NH—R6, where R6 is hydrogen, a lower alkyl group, an amino lower alkyl group, or the like; —O—R7, where R7 is hydrogen, a lower alkyl group, or the like; —(CH2)m—R8, where R8 is an amino group or the like, m is 1, 2, 3 or 4; or a cyclic amino group of Formula (2), where Y represents NH or C—R9aR9b, where R9a and R9b are each independently hydrogen, a lower alkyl group, an amino group, a lower alkyl amino group, or the like; n and p are 1 or 2; R3 is hydrogen, a halogen atom, a lower alkyl group, or the like; R4 is hydrogen or a carboxyl group-protecting group; and R5 is hydrogen or a hydroxyl group-protecting group.

Abstract: A pyridonecarboxylic acid derivative or a salt thereof is represented by Formula (1), where R1 is hydrogen, a halogen atom, a lower alkyl group, or an amino group; R2 is —NH—R6, where R6 is hydrogen, a lower alkyl group, an amino lower alkyl group, or the like; —O—R7, where R7 is hydrogen, a lower alkyl group, or the like; —(CH2)m—R8, where R8 is an amino group or the like, m is 1, 2, 3 or 4; or a cyclic amino group of Formula (2), where Y represents NH or C—R9aR9b, where R9a and R9b are each independently hydrogen, a lower alkyl group, an amino group, a lower alkyl amino group, or the like; n and p are 1 or 2; R3 is hydrogen, a halogen atom, a lower alkyl group, or the like; R4 is hydrogen or a carboxyl group-protecting group; and R5 is hydrogen or a hydroxyl group-protecting group.

Abstract: A pyridazinone derivative compound shown by the following formula (I): wherein R1 is selected from hydrogen, etc.; R2 is selected from substituted or unsubstituted aryl, etc.; R3 is hydrogen, etc.; p is 0, 1 or 2; R4 and R5, are each hydrogen, etc.; R6 and R7, are taken together to form a group of the formula: wherein R8 is hydrogen; X is selected from oxygen, etc; R10 is selected from hydrogen, etc.; R11 is selected from hydrogen, etc.; R12 is selected from hydrogen, etc.; R13 is selected from hydrogen, etc.; R14 is selected from hydrogen, etc.; m and n are each 0, 1, or 2, or a pharmaceutically acceptable salt thereof, which is useful as a medicament.