Questions – réponses sur l’utilisation du rivaroxaban pour le traitement de la maladie thromboembolique veineuse

[Proper use of apixaban: an outline for clinical practice]

Apixaban is a direct inhibitor of coagulation factor Xa. Superior efficacy over aspirin and antivitamin K has been shown in the prevention of stroke and systemic embolism during non-valvular atrial fibrillation with a more favorable safety profile, even though the risk of hemorrhage cannot be ignored, considering its mechanism of action. The recommended dose is 5mg twice daily which can be reduced to 2.5mg depending on the individual risk. Apixaban is also indicated for the treatment of venous thromboembolism but reimbursement has not yet been accepted in France for this indication. As with all direct oral anticoagulants, no routine biological monitoring is required, nevertheless their use may have an impact on all coagulation tests, eventually hampering interpretation. In particular clinical circumstances where a measure of anticoagulant efficacy is deemed necessary, specific assay of anti-Xa activity is appropriate, the result being expressed as concentration of the anticoagulant used. It is therefore necessary to state the name of the medicine for which the assay is requested. With these new anticoagulants, management of hemorrhagic events can be more difficult due to the lack of a specific antidote. Pro-hemostatic substances have exhibited efficacy in animal models but results are still insufficiently documented in clinical practice. Local or locoregional hemostasis measurements, when possible, are an essential factor in the treatment of hemorrhagic events.

Pharmacology and laboratory testing of the oral Xa inhibitors

New oral factor Xa inhibitors are intended to progressively substitute the oral vitamin K antagonists and parenteral indirect inhibitors of factor Xa in the prevention and treatment of venous and arterial thromboembolic episodes. This article focuses on the main clinical studies and on biological measurements of new oral factor Xa inhibitors, and addresses several safety issues. These newer agents do not require any routine laboratory monitoring of blood coagulation; however, biological tests have been developed in order to assess the plasma concentration of these drugs in several clinical settings. This article reviews these 4 oral direct factor Xa inhibitors.