2-pyrazolin-5-ones

A 2-pyrazolin-5-one or physiologically acceptable salts thereof useful as a protein kinase inhibitor has the formula (I) wherein R is optionally substituted indole, imidazole, 1,2,3-triazole, 1,2,4-triazole, benzimidazole, 4,5,6,7-tetrahydroindole, benzoindole, azaindole, indazole, pyridine, quinoline, pyrimidine, benzene, pyrazine, pyrrole, pyrazole, oxazole or thiazole; R1 is hydrogen or -A-Z; A is -(CH2)n-, -(CH2)n-NH-, -(CH2)n-O-, -(CH2)n-S-, -(CH2)n-S(O)- or -(CH2)n-S(O)2-; Z is -H, alkyl, aralkyl, trihalomethyl, trihalomethylcarbonyl, R3OC(O)-, -NR4R5, -C(O)NR4R5, R3CO-, R3O-, or an optionally substituted cycloalkane, isoxazole, isothiazole, imidazole, benzene, pyrrole, indole, pyridine, pyrazine, pyrimidine, benzothiazole, tetrahydrofuran, thiophene, imidazole, furan, triazine, benzimidazole, pyridazine, quinoxaline, pyrazole, oxazole, thiazole or N-oxides thereof; n is 0 to 3 and R3 to R5 are as defined in the specification limited by the provisos listed in the specification.