4,5-Functionalized 6-phenyl-3(2H)pyridazinones: synthesis and evaluation of antinociceptive activity

A series of 2-substituted 4,5-functionalized 6-phenyl-3(2H)-pyridazinones were synthesized and their antinociceptive activities were evaluated in the mouse abdominal constriction model. Single dose studies showed that compounds 11, 18a and 23 were more active than the reference drug, Emorfazone, in inhibiting the effects of the noxious chemical stimulus, p-phenylquinone. Subsequent dose-response studies revealed 18a to be almost seven-fold more potent than Emorfazone.