A thromboxane synthetase inhibitor in Raynaud's phenomenon.

The balance between thromboxane A2 (a vasoconstrictor) and prostacyclin (a vasodilator) may be important in the pathogenesis of Raynaud's phenomenon. Dazoxiben is a selective inhibitor of thromboxane synthetase, with no effect on prostacyclin synthetase. It has been shown to abolish cold induced forearm vasoconstriction in normal volunteers. We have compared its effect with that of placebo in a double blind crossover study in eight patients with severe Raynaud's phenomenon. No consistently clinically useful benefit was demonstrated from three weeks' treatment with dazoxiben, and there were no significant changes in finger temperature or finger blood flow. We conclude that dazoxiben at this dosage is unlikely to be of practical clinical benefit in Raynaud's phenomenon.