Effect of heparin injection on plasma protein binding of 1-anilino-8-naphthalenesulfonate and salicylate in rats.

After intravenous injection of heparin, the plasma protein binding of 1-anilino-8-naphthalenesulfonate (ANS) was remarkably decreased in rats. This effect occurred within one min after the injection of 1000 units/kg of heparin and lasted for about 30 min. The change in the binding of ANS was closely related to the plasma concentration of free acids (FFA), which was suggested as one of the heparin-induced inhibitors. The free fatty fraction of salicylate in plasma after the intravenous injection of heparin, has a pronounced variation, and also had a statistically significantly correlation with the plasma free fraction of ANS. It was suggested that ANS might be useful for the prediction of the heparin-induced changes in the plasma protein binding of acidic drugs.