Novel Antiasthmatic Agents with Dual Activities of Thromboxane A_2 Synthetase Inhibition and Bronchodilation. V.Thienopyridazinone Derivatives

Synthesis and pharmacological evaluation of novel thienopyridazinones and related compounds are described.A thiophene ring was found to be able to replace the benzene ring of a phthalazinone without loss of biological activities. This observation supports our hypothesis that the benzene ring plays an important role in both thromboxane A_2 (TXA_2) synthetase-inhibitory and bronchodilatory activities. Further, it was shown that the carbonyl moiety of a phthalazinone is not necessary for these activities.