Synthesis and Pharmacological Evaluation of 6-Arylpyridazinones as Potent Vasorelaxants.

Preclinical Research As part of a research program to identify compounds with potent antihypertensive properties, a new series of dihydropyridazin ‐ 3(2H) ‐ one analogs was synthesized and evaluated for vasodilator activity in rat thoracic aortic rings. Most of the newly synthesized compounds displayed good vasorelaxant activity as compared with SK&F ‐ 93741 and hydralazine, with the N2 ‐ unsubstituted 4 ‐ isobutyramidophenylpyridazinone derivative 5 being the most potent vasorelaxant, producing vasorelaxation greater than that of hydralazine and equipotent to SK&F ‐ 93741. A significant effect of the 6 ‐ phenyl substituents and substitution at N ‐ 2 position of pyridazinone nucleus on the vasodilatory activity was observed. [ABSTRACT FROM AUTHOR]