| abstract |
Disclosed are a 3(2H)-pyridazinone derivative of the formula (I) or its salt, a process for its production and a pharmaceutical composition containing thereof: (see formula I) (wherein R1, R2 and R3 are each hydrogen C1-4 alkyl, X is chlorine or bromine, Y1 is hydrogen, halogen, nitro, amino or C1-4 alkoxy, Y2 is hydrogen, halogen, hydroxyl, C1-4 alkyl or C1-4 alkoxy, A is C1-5 alkylene which may be substituted by hydroxyl, B is carbonyl or methylene which may be substituted by C1-4 alkyl, and R4 and R5 are each C1-4 alkyl, or R4 is hydrogen and R5 is -Z-Ar (wherein Z is C1-5 alkylene, and Ar is aromatic 6-membered ring which may contain nitrogen), or R4 and R5 together form C2-6 cyclic alkylene, or R4 and R5 form together with the adjacent nitrogen atom 4-substituted piperazine of the formula: (see formula II) wherein R6 is C1-4 alkyl). The derivative and its salt are useful as for a vasodilator, an antiallergic drug and an antiplatelet agent. |