Pyridazinone derivatives and salts thereof.

摘要

A pyradazinone derivative represented by the following general formula I; <CHEM> wherein R<1> represents hydrogen atom or alkyl group, R<2> represents hydrogen atom, alkyl group, alkoxy group or alkylthio group, R<3> represents hydrogen atom or alkyl group, each of R<4>, R<5> and R<6> represents hydrogen atom, hydroxy group or alkoxy group independently, or two of R<4>, R<5> and R<6> may join together to form -O-CH2-O- or -O-CH2-CH2-O-, n represents an integer of 0 to 4 and the dotted line represents single bond or double bond, or a salt thereof. The above compound is useful as a cardiotonic.