A series of new derivatives of 4-hydrazino-5H-pyridazino [4, 5-blindole (5) and 4- hydrazinopyridazino [4, 5-a] indole (12) have been synthesized to investigate their activities as selective thromboxane synthetase inhibitors as well as antihypertensive agents. Several of the prepared compounds were found to be selective thromboxane synthetase inhibitors, in concordance with the Gorman mode1. l The most potent were 8-(benzyloxy)-3, 4- ...