Pirmagrel is the selective thromboxane synthetase inhibitor. The compound was well tolerated by all subjects without evidence of any adverse reactions. Serum thromboxane B2 levels (the stable metabolic product of thromboxane A2) were significantly reduced after administration of the compound, with the maximal effect of a 99 per cent reduction occurring at 0.5 and 1 hour after administration. Bleeding times showed a slight increase 2 hours after administration of the compound. Pirmagrel was able to completely prevent the increase in serum thromboxane B2 following allergen challenge in asthmatic patients; while it caused a very small reduction in the early response to allergen, there was no effect on the late response or on airway hyperresponsiveness. Pirmagrel was developed for the treatment of ischemic heart disorders and thrombosis. However, this development was discontinued.