Carbostyril compounds

A carbostyril compound represented by the formula (I):

• ##STR116## wherein R.sub.1 represents a hydrogen atom, a straight or branched chain alkyl group having 1 to 6 carbon atoms or a phenylalkyl group selected from the group consisting of monophenylalkyl and diphenylalkyl groups having a straight or branched chain alkyl group having 1 to 6 carbon atoms in the alkyl moiety thereof, R.sub.2 represents a straight or branched chain alkenyl group having 2 to 6 carbon atoms, an alkoxyalkyl group having a straight or branched chain alkoxy group of 1 to 6 carbon atoms in the alkoxy moiety thereof and a straight or branched chain alkylene group of 1 to 6 carbon atoms in the alkyl moiety thereof, a mono hydroxyalkyl group having a straight or branched chain alkyl group of 1 to 6 carbon atoms, a carboxyalkyl group having a straight or branched chain alkylene group of 1 to 6 carbon atoms in the alkyl moiety thereof, an alkylcarbonyl group having a straight or branched chain alkyl group of 1 to 6 carbon atoms in the alkyl moiety thereof, a cycloalkylcarbonyl group having a cycloalkyl group of 3 to 7 carbon atoms in the cycloalkyl moiety thereof, an alkylcarbonylalkyl group having a straight or branched chain alkylene group of 1 to 6 carbon atoms and the alkyl carbonyl group as defined hereinabove for R.sub.2, an alkoxycarbonylalkyl group having an alkoxycarbonyl moiety consisting of a straight or branched chain alkoxy group having 1 to 6 carbon atoms attached to a carbonyl group and a straight or branched chain alkyl group having 1 to 6 carbon atoms in the alkyl moiety thereof, a straight or branched chain alkynyl group having 2 to 7 carbon atoms or a carbamoylalkyl group having a straight or branched chain alkylene group of 1 to 6 carbon atoms in the alkyl moiety thereof and a carbamoyl group which may be substituted on the nitrogen atom thereof with an alkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted phenylalkyl group, R.sub.3 and R.sub.4, which may be the same or different, each represents a hydrogen atom, a straight or branched chain alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, an alkoxyalkyl group having a straight or branched chain alkoxy group of 1 to 6 carbon atoms in the alkoxy moiety thereof and a straight or branched chain alkylene group of 1 to 6 carbon atoms in the alkyl moiety thereof, a straight or branched chain alkenyl group having 2 to 6 carbon atoms, a phenylalkyl group selected from the group consisting of monophenylalkyl and diphenylalkyl groups having a straight or branched chain alkyl group having 1 to 6 carbon atoms in the alkyl moiety thereof, a phenoxyalkyl group having a straight or branched alkylene group of 1 to 6 carbon atoms in the alkyl moiety thereof, or a phenyl group, the 3,4-bond of the carbostyril nucleus represents a single or double bond, said phenyl, phenylalkyl or phenoxyalkyl being unsubstituted or having 1 to 3 substituents being selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, halogen atoms, alkylenedioxy groups having 1 to 2 carbon atoms, carbamoyl and substituted or unsubstituted phenyl, and the pharmaceutically acceptable acid addition salts thereof.