Anticoagulants, Hematologic Class Summary Once the diagnosis of VTE is made, therapeutic anti-coagulation should be initiated in the absence of contra-indications. Anticoagulants prevent recurrent or ongoing thromboembolic occlusion of the vertebrobasilar circulation. In patients with heparin-induced thrombocytopenia, LVAD implantation has been performed successfully, albeit with additional risk, by using alternative anticoagulants. Heparin May be used if thrombocytopenia is not present. Heparin augments activity of antithrombin III and prevents conversion of fibrinogen to fibrin. Does not actively lyse but is able to inhibit further thrombogenesis. Prevents recurrence of a clot after spontaneous fibrinolysis. Warfarin (Coumadin, Jantoven) Warfarin, which is administered orally, is used if long-term anticoagulation is needed. The international normalized ratio (INR) is followed, with a target range of 2-3. A CT scan of the brain must be done prior to any anticoagulant use to rule out preexisting intracranial hemorrhage. Enoxaparin (Lovenox) Enoxaparin is produced by the partial chemical or enzymatic depolymerization of unfractionated heparin (UFH). LMWH differs from UFH by having a higher ratio of antifactor Xa to antifactor IIa. Enoxaparin binds to antithrombin III, enhancing its therapeutic effect. The heparin-antithrombin III complex binds to and inactivates activated factor X (Xa) and factor II (thrombin). It does not actively lyse but is able to inhibit further thrombogenesis, preventing clot reaccumulation after spontaneous fibrinolysis. The advantages of enoxaparin include intermittent dosing and a decreased requirement for monitoring. Heparin anti–factor Xa levels may be obtained if needed to establish adequate dosing. There is no utility in checking activated partial thromboplastin time (aPTT); the drug has a wide therapeutic window, and aPTT does not correlate with the anticoagulant effect. The maximum antifactor Xa and antithrombin activities occur 3-5 hours after administration. Dalteparin (Fragmin) LMW heparin with antithrombotic properties; enhances inhibition of Factor Xa and thrombin by antithrombin, minimal effect on APTT Tinzaparin LMW heparin with antithrombotic properties; enhances inhibition of Factor Xa and thrombin by antithrombin, minimal effect on APTT Argatroban Argatroban is a selective thrombin inhibitor that inhibits thrombin formation by binding to the active thrombin site of free and fibrin-bound thrombin. Inhibits thrombin-induced platelet aggregation. Dabigatran etexilate (Pradaxa) Dabigatran etexilate is a selective thrombin inhibitor that inhibits thrombin formation by binding to the active thrombin site of free and fibrin-bound thrombin. Inhibits thrombin-induced platelet aggregation. Bivalirudin (Angiomax) Bivalirudin inhibits coagulant effects by preventing thrombin-mediated cleavage of fibrinogen to fibrin. Lepirudin (Refludan) Lepirudin inhibits coagulant effects by preventing thrombin-mediated cleavage of fibrinogen to fibrin. Fondaparinux (Arixtra) Fondaparinux is a synthetic heparin pentasaccharide that causes an antithrombin lll mediated selective inhibition of factor Xa. This interrupts the blood coagulation cascade, which in turn inhibits thrombin formation and thrombus development. Rivaroxaban (Xarelto) Rivaroxaban is a selective and reversible inhibition factor of Xa (FXa) in the intrinsic and extrinsic coagulation pathways. This interrupts the blood coagulation cascade, which in turn inhibits thrombin formation and thrombus development.
Posted on: Thu, 08 Jan 2015 00:14:28 +0000
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