Novel Oral Anticoagulant Complications



  • Over last decade several novel oral anticoagulants (NOACs) have been developed:
    • Direct thrombin inhibitors (Dabigatran)
    • Factor Xa inhibitors (Apixaban, Edoxaban, Rivaroxaban)
  • Direct thrombin inhibitors inhibit both free and fibrin-bound thrombin as well as thrombin-induced platelet aggregation
  • Factor Xa inhibitors cause selective and reversible inhibition of factor Xa in both the intrinsic and extrinsic coagulation pathways
  • All four agents are metabolized through the liver and eliminated by the kidneys; dabigatran > edoxaban > rivaroxaban > apixaban
  • Commonly used for both prophylaxis and treatment of stroke, myocardial infarction, valvular disease, and venous thromboembolism
  • Measurement of anticoagulant effect is not routinely needed:
    • Prothrombin time (PT)/International Normalization Ratio (INR) are of limited utility in measuring anticoagulant effect
    • Best screening tests of anticoagulant effect in direct thrombin inhibitors are thrombin time (TT) and ecarin clotting time (ECT)
    • Best screening test of anticoagulant effect in factor Xa inhibitors is chromogenic anti-FXa assays
  • Contraindications include any condition in which the risk of hemorrhage or adverse reaction outweighs clinical benefit
    • Prior hypersensitivity
    • Severe renal impairment
    • Hepatic impairment
    • Active or potential GI, intracerebral, or genitourinary bleeding


  • Bleeding incidence:
    • Overall major bleeding events < warfarin
      • Less incidence of intracranial hemorrhage (ICH) than warfarin
      • Higher incidence of GI bleeding than warfarin
  • Thrombotic event:
    • In patients who do not or cannot take prescribed NOACs are at risk for a thrombotic event

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