Pyridazinyl phenyl hydrazones useful against congestive heart failure

Abstract From the Canadian patent

Therapeutically active compounds of formula (I) in which R1 to R4 means hydrogen, alkyl, alkenyl, aryl, arylalkyl carboxyalkyl, hydroxyalkyl or , halogenalkyl or R2 and R3 form a ring of 5-7 carbon atoms R5 to R9 means , hydrogen, alkyl, alkenyl aryl, arylalkyl, acyl, hydroxy, alkoxy alkoxycarbonyl, amino, acylamino, alkylamino aryloxy, halogen, cyano, nitro, carboxy alkylsulfonyl, sulfonamido or trifluoromethyl wherein each aryl , residue defined above by itself or as a part of another group may be substituted, and pharmaceutically acceptable salts and esters thereof. The compounds increase the calcium sensitivity of contractile proteins of the cardiac muscle and are thus useful in the …