Effects of dazoxiben on arrhythmias and ventricular fibrillation induced by coronary artery occlusion and reperfusion in anaesthetised greyhounds.

1 The effects of the thromboxane synthetase inhibitor dazoxiben (UK 37248) on haemodynamics, blood gases, thromboxane and prostacyclin release and on arrhythmias were examined in anaesthetised greyhounds subject to acute coronary artery occlusion and reperfusion. 2 Ten minutes after the administration of UK 37248 2 mg/kg intravenously, the plasma concentration of thromboxane B2 in the coronary sinus was significantly reduced whereas the 6-keto-prostaglandin F1 alpha concentration was increased. 3 UK 37248 did not significantly alter the number of arrhythmias or the incidence of ventricular fibrillation resulting from coronary artery occlusion. There was evidence, however, that in some drug-treated animals there may have been incomplete inhibition of thromboxane synthesis during coronary artery occlusion. 4 A further dose of 1 mg/kg UK 37248 was administered intravenously 5 min before the release of the 40 min coronary artery occlusion. Seven out of eight control dogs died in ventricular fibrillation following reperfusion whereas only one out of eight drug-treated animals fibrillated. 5 This latter result suggests that thromboxane may be an important factor in reperfusion induced ventricular fibrillation and that dazoxiben may be a useful drug in clinically related situations.