Patent ID: 8450319

Claim:
A pyrrolopyridazinone compound represented by the formula (1): wherein R 1 represents a C 1 -C 2 alkyl group or a halogeno C 1 -C 2 alkyl group, R 2 represents a C 3 -C 5 cycloalkyl group, a (C 3 -C 5 cycloalkyl)C 1 -C 2 alkyl group or a C 1 -C 3 alkyl group, or a methylene group which constitutes a substituted tetrahydrofuran ring or 3,6-dihydro-2H-pyran ring in combination with a group R 3 , R 3 represents a hydrogen atom, or a methylene group or a cis-vinylene group each of which is a group for constituting a substituted tetrahydrofuran ring or 3,6-dihydro-2H-pyran ring in combination with a group —O—R 2 , R 4 represents a hydrogen atom; a halogen atom; a C 1 -C 8 alkyl group; a C 2 -C 6 alkenyl group; a C 2 -C 6 alkynyl group; a hydroxy C 3 -C 6 alkenyl group; a hydroxy C 3 -C 6 alkynyl group; a C 1 -C 6 alkyl group substituted by a substituent(s) selected from Substituent group (a); a C 3 -C 6 cycloalkyl group which may be substituted by a substituent(s) selected from Substituent group (b); a C 1 -C 3 alkyl group which is substituted by a C 3 -C 6 cycloalkyl group which may be substituted by a substituent(s) selected from Substituent group (b), and which may be substituted by a hydroxy group; an aromatic ring group or heteroaromatic ring group each of which may be substituted by a substituent(s) selected from Substituent group (c); or a C 1 -C 2 alkyl group which is substituted by an aromatic ring group or heteroaromatic ring group each of which may be substituted by a substituent(s) selected from Substituent group (c), and which may be substituted by a hydroxy group; Substituent group (a) represents a halogen atom, a hydroxy group, a cyano group, a carboxy group, a C 1 -C 5 alkoxy group, a halogeno C 1 -C 4 alkoxy group, a C 3 -C 6 cycloalkoxy group, a (C 3 -C 6 cycloalkyl)C 1 -C 2 alkoxy group, a C 1 -C 4 alkoxycarbonyl group, a C 2 -C 4 alkanoyl group, a C 2 -C 4 alkanoyloxy group or a C 1 -C 4 alkyl-substituted amino group, Substituent group (b) represents a hydroxy group or a halogen atom, Substituent group (c) represents a halogen atom, a hydroxy group, a cyano group, a nitro group, a carboxy group, a C 1 -C 5 alkoxy group, a C 1 -C 4 alkoxycarbonyl group, a C 2 -C 4 alkanoyloxy group, a C 1 -C 4 alkyl-substituted amino group or a C 1 -C 4 alkyl group which may be substituted by a substituent(s) selected from the group consisting of a halogen atom, a hydroxy group and a carboxy group, or a pharmaceutically acceptable salt thereof.