The vitamin K-antagonism of salicylate and warfarin.

When administered in high dosages, salicylate acts as a vitamin K-antagonist: it induces a decrease of the plasma concentration of the Gla-containing coagulation factors and an accumulation of microsomal substrates for vitamin K-dependent carboxylase in the liver and in the lung. In vitro the drugs inhibit the DTT-dependent reductases which mediate the reduction of vitamin K epoxide and vitamin K quinone. NADH-dependent reductase and vitamin K-dependent carboxylase are not inhibited.