Comparison of sustained antithrombotic effects of inhibitors of thrombin and factor Xa in experimental thrombosis

B. J. Biemond, P. W. Friederich, M. [=Marcel M.] Levi, G. P. Vlasuk, H. R. Büller, J. W. ten Cate

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Abstract

In the pathogenesis of (recurrent) thrombosis, clot-associated thrombin appears to play an important role. Antithrombin III-independent thrombin inhibitors have been shown to neutralize clot-bound thrombin effectively. We compared the sustained antithrombotic effects and the effects on endogenous fibrinolysis of several of these agents with recombinant tick anticoagulant peptide (rTAP), a selective factor Xa inhibitor, and low-molecular-weight heparin (LMWH) in an experimental venous thrombosis model. Rabbits received either recombinant hirudin (rHir), Hirulog-1, CVS#995 (a novel direct inhibitor of thrombin), rTAP, LMWH, or saline. The effect on thrombus growth was assessed by measuring the accretion of 125I-labeled fibrinogen onto preformed nonradioactive thrombi, and the effect on endogenous fibrinolysis was assessed by measuring the decline in radioactivity of preformed 125I-labeled thrombi in rabbit jugular veins. All direct thrombin inhibitors induced a sustained antithrombotic effect compared with either LMWH and rTAP. In addition, CVS#995 also further decreased thrombus size after stopping its infusion, which was due to a significant enhancement of endogenous fibrinolysis. Direct thrombin inhibition by rHir, Hirulog-1, or CVS #995 induces a sustained antithrombotic effect compared with rTAP and LMWH, which is most likely due to inhibition of clot-bound thrombin. CVS#995 was shown to also enhance the extent of endogenous fibrinolysis to a greater degree compared with rHir and might therefore be an interesting new antithrombotic agent for the treatment of venous and arterial thrombosis
Original languageEnglish
Pages (from-to)153-160
JournalCirculation
Volume93
Issue number1
Publication statusPublished - 1996

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