Tricyclic dihydropyridazinones and pharmaceutical compositions containing them

A compound selected from the group consisting of :

• 4,4a-dihydro-5H-indeno[1,2-c]pyridazin-3-one-7-amino;
• 4,4a-dihydro-5H-indeno[1,2-c]pyridazin-3-one-7-formamide;
• 4,4a-dihydro-5H-indeno[1,2-c]pyridazin-3-one-7-acetamide;
• 4,4a-dihydro-5H-indeno[1,2-c]pyridazin-3-one-7-benzamide;
• 4,4a-dihydro-5H-indeno[1,2-c]pyridazin-3-one-7-(3', 4',5'-trimethoxy)-benzamide;
• 4,4a-dihydro-5H-indeno[1,2-c]pyridazin-3-one-7-nicotinyl-amide;
• 4,4a,5,6-tetrahydro-2H-benzo(h)cinnolin-3-one-8-acetamide;
• 4,4a,5,6-tetrahydro-2H-benzo(h)-cinnolin-3-one-8-2'-chloroacetamide;
• 2-n-butyl-4,4a,5,6-tetrahydro-2H-benzo(h)cinnolin-3-one-8-amino;
• 2-n-butyl-2,4,4a,5,6,7-hexahydro-3H-[6,7]-cyclohepten-[1,2-c]-pyridazin-3-o ne-8-amino;
• 2-n-butyl-2,4,4a,5,6,7-hexahydro-3H-[6,7]-cyclohepten-[1,2-c]-pyridazin-3-o ne-8-benzamide;
• 2,4,4a5,6,7-hexahydro-3H-benzo-[6,7]-cyclohepten[1,2-c]-pyridazin-3-one-8-a mino;
• 2,4,4a,5,6,7-hexahydro-3H-benzo-[6,7]-cyclohepten[1,2-c]-pyridazin-3-one-8- acetamide;
• 2,4,4a,5,6,7-hexahydro-3H-benzo-[6,7]-cyclohepten[1,2-c]-pyridazin-3-one-8- benzamide;
• and their non toxic salts.

An antihypertensive, vasodilating, anti-aggregating, anti-thrombotic or cytoprotective pharmaceutical or veterinary composition in a form suitable for adminstration by intravenous, subcutaneous, intramuscular, rectal or implant routes, said composition comprising a pharmaceutically and/or veterinarily acceptable carrier and/or diluent and an antihypertensively, vasodilatingly, anti-aggregatingly, anti-thrombotically or cytoprotectively effective amount of a compound of formula I ##STR28## wherein;

• n is zero or an integer of 1 to 2
• R is hydrogen, C.sub.1 -C.sub.6 lower alkyl, --CH.sub.2 --CH.dbd.CH.sub.2,--CH.sub.2 --C.tbd.CH and (CH.sub.2).sub.m --C.sub.6 H.sub.5 where m is zero or an integer of 1 to 3;
• at least one of R.sub.1 and R.sub.2 is selected from the group consisting of
• (a) R.sub.3 --CO-- wherein R.sub.3 is selected from the group consisting of a C.sub.1 -C.sub.16 branched or unbranched alkyl chain which may be substituted by hydroxy, amino, halogen, thiol, or free or esterified carboxy group;
• a heterocyclic ring wherein R.sub.3 CO is the acyl part of a carboxylic acid R.sub.3 CO.sub.2 H selected from the group consisting of nictoinic, isonicotinic, pyrazol-3-carboxylic, isoxazol-3-carboxylic, isoxazol-5-carboxylic, 2-thiophencarboxylic and 2-furylcarboxylic acids;
• an aromatic ring wherein R.sub.3 CO is the acyl part of a carboxylic acid R.sub.3 CO.sub.2 H selected from the group consisting of benzoic, toluic, 3,4,5-trimethoxybenzoic, p-hydroxy-3,5-dimethoxybenzoic, p-fluorobenzoic, p-chlorobenzoic, p-aminobenzoic, salicyclic, and p-hydroxybenzoic acid;
• a C.sub.3 -C.sub.7 cycloaliphatic ring;
• a C.sub.4 -C.sub.15 cycloaliphatic alkyl group;
• phenyl lower alkyl or phenoxy lower alkyl;
• moieties wherein R.sub.3 CO is the acyl part of a carboxylic acid R.sub.3 CO.sub.2 H selected from the group consisting of 1-imidazolylacetic, 2-furylpropionic, 2-tetrahydrofurylpropionic, cinnamic, 2-fluoro-cinnamic, and caffeic acid;
• a lower C.sub.1 -C.sub.6 alkoxy, benzyloxy or NHR.sub.6 group, wherein R.sub.6 is hydrogen, C.sub.1 -C.sub.6 lower alkyl or --CH.sub.2 --C.sub.6 H.sub.5 ;
• (b) R.sub.4 SO.sub.2 --, wherein R.sub.4 is CH.sub.3, C.sub.2 H.sub.5, phenyl or p-methylphenyl;
• and the other of R.sub.1 and R.sub.2 is selected from the group consisting of hydrogen, C.sub.1 -C.sub.6 lower alkyl, (CH.sub.2).sub.m --C.sub.6 H.sub.5, (CH.sub.2).sub.m --C.sub.6 H.sub.11, (CH.sub.2).sub.m --C.sub.5 H.sub.9 where m is zero or an integer of 1 to 3, --CH.sub.2 --CH.dbd.CH.sub.2, --CH.sub.2 --C.tbd.CH, R.sub.3 --CO--, and R.sub.4 SO.sub.2 --
• and racemic or optically active enantiomers;
• and pharmaceutically acceptable salts thereof.