Beneficial effect of sulfamethoxazole and trimethoprim on accelerated coagulation.

We have shown that the drug combination of sulfamethoxazole and trimethoprim has a radio protective effect in mice. Since radiation injury is due in part to microvascular thrombosis produced by the release or action of thromboplastin, we evaluated the effect of these drugs individually on thromboplastin-accelerated coagulation. Sulfamethoxazole at a final concentration of 0.05 microgram/ml and trimethoprim at concentrations of 0.005 and 0.05 microgram/ml significantly prolonged the recalcification times of human plasma. Whether these drugs have an anticoagulant effect when employed clinically remains to be determined.