A compound of formula: or a pharmaceutically acceptable salt, solvate, isotope, polymorph or tautomer thereof, wherein A is a radical selected from A 1, A 2, A 3 and A 4; A 1 is A 2 is A 3 is A 4 is R 1 and R 2 are independently selected from hydrogen, C 1-4 alkyl, haloC 1-4 alkyl, hydroxyC 1-4 alkyl and C 1-4 alkoxyC 1-4 alkyl; R 3, R 4, R 5, R 6 and R 7 are independently selected from hydrogen, -OH, halogen, C 1-6 alkyl, C 3-6 cycloalkyl, -NR 12 R 13, -N(R 12)COR 13, -N(R 12)SO 2 R 13, haloC 1-6 alkyl, hydroxyC 1-6 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-6 alkyl, -COOR 12, -CN, -CONR 12 R 13, -SO 2 -C 1-4 alkyl, -SO 2 -O-C 1-4 alkyl and -SO 2 -NR 12 R 13; R 8 is selected from C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, haloC 1-6 alkyl, hydroxyC 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 3-6 cycloalkylC 1-4 alkyl, PhC 1-4 alkyl and -C 1-4 alkyl-CONR 12 R 13; R 9, R 10 and R 11 are independently selected from hydrogen, C 1-6 alkyl, C 3-6 cycloalkylC 0-4 alkyl, -NR 12 R 13, -N(R 12)COR 13, -N(R 12)SO 2 R 13, haloC 1-6 alkyl, hydroxyC 1-6 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-6 alkyl, -COOR 12, -CN, -CONR 12 R 13, -SO 2 -C 1-4 alkyl, -SO 2 -O-C 1-4 alkyl and -SO 2 -NR 12 R 13; and each R 12 and R 13 are independently selected from hydrogen and C 1-4 alkyl, wherein the term C 3-6 cycloalkyl, as a group or as a part of a group, means a nonaromatic, monocyclic, hydrocarbon ring group comprising 3 to 6 carbon atoms, which can be optionally substituted by one or more substituents independently selected from C 1-4 alkyl, C 1-4 alkoxy and halogen, and wherein the Ph term means a phenyl group which can be optionally substituted by one or more substituents independently selected from C 1-4 alkyl, C 1-4 alkoxy and halogen; with the proviso that the following products are excluded: 1-methyl-6-oxo-1,6-dihydro-pyridine-2-carboxylic acid N '-phenylhydrazide, 1-benzyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-(2-(trifluoromethyl)phenyl)-hydrazide, 1-benzyl-4,6-dimethyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-phenyl-hydrazide, 1-methyl-2-oxo-1,2-dihydro-pyridine-4-carboxylic acid N'-(2,4,6-trichlorophenyl)-hydrazide, 1-((3-methylphenyl)methyl)-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-(3-(trifluoromethyl)phenyl)-hydrazide and 1-((2-chlorophenyl)methyl)-6-oxo-1,6-dihydro-pyridine-3-carboxylic acid N'-phenyl-N'-methyl-hydrazide. A is a radical selected from A 1, A 2, A 3 and A 4; A 1 is A 2 is A 3 is A 4 is R 1 and R 2 are independently selected from hydrogen, C 1-4 alkyl, haloC 1-4 alkyl, hydroxyC 1-4 alkyl and C 1-4 alkoxyC 1-4 alkyl; R 3, R 4, R 5, R 6 and R 7 are independently selected from hydrogen, -OH, halogen, C 1-6 alkyl, C 3-6 cycloalkyl, -NR 12 R 13, -N(R 12)COR 13, -N(R 12)SO 2 R 13, haloC 1-6 alkyl, hydroxyC 1-6 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-6 alkyl, -COOR 12, -CN, -CONR 12 R 13, -SO 2 -C 1-4 alkyl, -SO 2 -O-C 1-4 alkyl and -SO 2 -NR 12 R 13; R 8 is selected from C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, haloC 1-6 alkyl, hydroxyC 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 3-6 cycloalkylC 1-4 alkyl, PhC 1-4 alkyl and -C 1-4 alkyl-CONR 12 R 13; R 9, R 10 and R 11 are independently selected from hydrogen, C 1-6 alkyl, C 3-6 cycloalkylC 0-4 alkyl, -NR 12 R 13, -N(R 12)COR 13, -N(R 12)SO 2 R 13, haloC 1-6 alkyl, hydroxyC 1-6 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-6 alkyl, -COOR 12, -CN, -CONR 12 R 13, -SO 2 -C 1-4 alkyl, -SO 2 -O-C 1-4 alkyl and -SO 2 -NR 12 R 13; and each R 12 and R 13 are independently selected from hydrogen and C 1-4 alkyl, wherein the term C 3-6 cycloalkyl, as a group or as a part of a group, means a nonaromatic, monocyclic, hydrocarbon ring group comprising 3 to 6 carbon atoms, which can be optionally substituted by one or more substituents independently selected from C 1-4 alkyl, C 1-4 alkoxy and halogen, and wherein the Ph term means a phenyl group which can be optionally substituted by one or more substituents independently selected from C 1-4 alkyl, C 1-4 alkoxy and halogen; with the proviso that the following products are excluded: 1-methyl-6-oxo-1,6-dihydro-pyridine-2-carboxylic acid N '-phenylhydrazide, 1-benzyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-(2-(trifluoromethyl)phenyl)-hydrazide, 1-benzyl-4,6-dimethyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-phenyl-hydrazide, 1-methyl-2-oxo-1,2-dihydro-pyridine-4-carboxylic acid N'-(2,4,6-trichlorophenyl)-hydrazide, 1-((3-methylphenyl)methyl)-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-(3-(trifluoromethyl)phenyl)-hydrazide and 1-((2-chlorophenyl)methyl)-6-oxo-1,6-dihydro-pyridine-3-carboxylic acid N'-phenyl-N'-methyl-hydrazide. 1-methyl-6-oxo-1,6-dihydro-pyridine-2-carboxylic acid N '-phenylhydrazide, 1-benzyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-(2-(trifluoromethyl)phenyl)-hydrazide, 1-benzyl-4,6-dimethyl-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-phenyl-hydrazide, 1-methyl-2-oxo-1,2-dihydro-pyridine-4-carboxylic acid N'-(2,4,6-trichlorophenyl)-hydrazide, 1-((3-methylphenyl)methyl)-2-oxo-1,2-dihydro-pyridine-3-carboxylic acid N'-(3-(trifluoromethyl)phenyl)-hydrazide and 1-((2-chlorophenyl)methyl)-6-oxo-1,6-dihydro-pyridine-3-carboxylic acid N'-phenyl-N'-methyl-hydrazide.