Novel antiasthmatic agents with dual activities of thromboxane A2 synthetase inhibition and bronchodilation. IV. 2-[2-(1-Imidazolyl)ethyl]-4-(3-pyridyl)-1(2H)-phthalazinones.

Synthesis and pharmacological evaluation of several compounds related to 2-[2-(1-imidazolyl)ethyl]-4-(3-pyridyl)-1(2H)-phthalazinones are described. The phenyl moiety of the phthalazinone skeleton was found to play an important role in both thromboxane A2 synthetase-inhibitory and bronchodilatory activities. Further, the 3-pyridyl group at the 4-position was shown to be necessary for in vivo thromboxane A2 synthetase-inhibitory activity.