Direct factor Xa inhibitors ('xabans') are a class of anticoagulant drugs which act directly upon Factor X in the coagulation cascade, without using antithrombin as a mediator.

Factor Xa inhibitors may be quantified with an anti-Xa assay calibrated with drug-specific standards.

A normal prothrombin time probably excludes excess levels of rivaroxaban and edoxaban, but not apixaban. Patients with minor and moderate DOAC-associated bleeding can be treated with supportive care and general hemostatic measures. Nonspecific reversal agents (eg, prothrombin complex concentrate, activated prothrombin complex concentrate) are of unproven benefit, carry a risk of thrombosis, and should be reserved for severe bleeding. Specific reversal agents, such as idarucizumab (a monoclonal antibody fragment that binds dabigatran) and andexanet alfa (a recombinant factor Xa variant that binds factor Xa inhibitors but lacks coagulant activity), are in clinical development ¹⁾.

Bobby L, Westlake E, Esplin N, Young S. Activated prothrombin complex concentrate for reversal of oral factor Xa inhibitors at a level 1 trauma center. Thromb Res. 2021 Aug 10;206:33-35. doi: 10.1016/j.thromres.2021.08.005. Epub ahead of print. PMID: 34399122.

A 46-year-old man presented with headache, right hemiparesis, and motor aphasia. A diagnosis of cerebral venous thrombosis with subarachnoid hemorrhage was made. We started intravenous administration of unfractionated heparin. After 6 days in hospital, the right hemiparesis and motor aphasia worsened, and brain computed tomographic(CT)images demonstrated intracerebral hemorrhage in the left parietal lobe. Therefore, we switched treatment from heparin to apixaban. His condition improved and a brain magnetic resonance(MR)venogram after 7 days in hospital showed recanalization of the cerebral veins. He was discharged with no apparent neurological defects 33 days after onset and his modified Rankin Scale score was 1. In cases of progressive cerebral venous thrombosis with intracerebral hemorrhage, during anticoagulation, it is necessary to achieve recanalization of the occluded cerebral vein rapidly without spreading the intracerebral hemorrhage. Factor Xa inhibitors, especially apixaban, may be another option for treating cerebral venous thrombosis with intracerebral hemorrhage ²⁾.