Abstract: 3-(1-Pyrazolyl)-pyridazine derivatives of the formula I, or pharmaceutically acceptable acid addition salts thereof, which decrease high blood pressure and inhibit catabolism or prostaglandins, ##STR1## wherein R.sup.1 is hydrogen or C.sub.1-4 alkyl,R.sup.2 is hydrogen, cyano, carboxyl, carbamoyl, carbaxoyl or C.sub.1-4 alkoxycarbonyl,R.sup.3 is hydrogen or chlorine or --NR.sup.4 NHR.sup.5 or NR.sup.6 R.sup.7, wherein R.sup.4 and R.sup.5 are each hydrogen or C.sub.1-4 alkyl, wherein R.sup.6 and R.sup.7 are each hydrogen or C.sub.1-5 alkyl, C.sub.1-5 hydroxyalkyl, C.sub.3-7 cycloalkyl, phenyl or benzyl, or benzyl or phenylethyl substituted with one or two chlorine atoms or methoxy groups, or a furylmethyl, pyridylmethyl, pyrrolidine or piperazine ring, or when R.sup.7 is hydrogen, R.sup.6 is --(CH.sub.2).sub.n --NR.sup.4 R.sup.5 wherein n is an integer from 1 to 3.

Abstract: The invention relates to compounds of general formula ##STR1## wherein R.sup.1 stands for a hydrogen atom or a C.sub.1-6 alkyl-, a C.sub.2-4 hydroxyalkyl, a C.sub.3-6 cycloalkyl or a phenyl group,R.sup.2 stands for a hydrogen, fluorine, chlorine or bromine atom or a C.sub.1-6 alkyl, a C.sub.2-4 hydroxyalkyl, a nitro or an --NR.sup.5 R.sup.6 group, wherein R.sup.5 and R.sup.6 may have the same or different meaning and stand each for a hydrogen atom or a C.sub.1-4 alkyl or a C.sub.2-4 hydroxyalkyl group,R.sup.3 stands for a hydrogen atom or a C.sub.1-6 alkyl, a C.sub.2-4 hydroxyalkyl, a C.sub.3-6 cycloalkyl or a phenyl group, a chlorine atom or a hydroxyl, amino or methoxy group,R.sup.4 stands for a carbamoyl, a cyano or an --NR.sup.7 --NHR.sup.8 group, wherein R.sup.7 and R.sup.8 may have the same or different meaning and stand each for a hydrogen atom or a C.sub.1-4 alkyl, a C.sub.2-4 hydroxyalkyl, a C.sub.1-4 alkoxycarbonyl or an --NR.sup.9 R.sup.10 group, wherein R.sup.9 and R.sup.