Inhibition of intravascular fibrin deposition by dipyridamole in experimental animals

Intravascular fibrin deposition was induced in rabbits by endotoxin, the infusion of fibrin monomer (FM), and by the infusion of thrombin and EACA. A previously developed radioisotope technique was used to measure the fibrin deposits in various organs. Dipyridamole treatment of rabbits caused significant inhibition of fibrin deposition in all three experimental models. The drug also inhibited platelet consumption and, in the thrombin- and EACA-infused animals, fibrinogen consumption as well. The results obtained with dipyridamole were compared with the effect of thorotrast. It was concluded from this comparison that the effect of dipyridamole could not be attributed to inhibition of the reticuloendothelial system. It is postulated that dipyridamole inhibits the final step at which soluble FM is precipitated as fibrin in vivo.