Effect of acute administration of acetysalicylic acid on the prothrombin activity of bishydroxycoumarin-treated rats.

L INK AND COWORKERS’234 were the first to show that a chemical and pharmacologic relationship exists between bishydroxycoumarin ( BHC ), its analogs and structurally related compounds and salicylic acid. Subsequently, it was found that methyl salicylate caused hypoprothrombinemia in rabbits but not in dogs.5 Several workers5#{176} have reported that chronic administration of acetylsalicylic acid (ASA) in relatively high doses to normal and hospitalized persons consistently produces hypoprothrombinemia. On the other hand, a single dose of the drug rarely produces a significant change in prothrombin activity. The effects of various drugs on the action of coumarins have been studied in recent years, but we have been unable to find any information concerning the effect of ASA on the hypoprothrombinemia induced by administration of BHC. The results of experiments on the interaction of these two drugs recently conducted in our laboratory are presented herewith.