Is xarelto a factor Xa inhibitor?

Key Points. In 2008, rivaroxaban (Xarelto; Bayer HealthCare) became the first orally administered direct factor Xa inhibitor to be approved for clinical use in the prevention of venous thromboembolism (VTE) after elective hip- or knee-replacement surgery.

What labs do you monitor for Xarelto?

testing, Factor X chromogenic, Protein S activity and clotting factor activities. Testing for Protein C, antithrombin and fibrinogen activity should be accurate on rivaroxaban. according to bleeding risk – restart the drug 24 – 72 hours after a procedure.

Does xarelto affect PTT and PT?

Previous studies have shown that excessive rivaroxaban may cause PT prolongation but has no effect on aPTT. Rivaroxaban can produce concentration-dependent prolongation of PT, and the prolonged PT may provide some quantitative information about the risk of bleeding.

How does factor Xa anticoagulant work?

Factor Xa inhibitors are a type of anticoagulant that work by selectively and reversibly blocking the activity of clotting factor Xa, preventing clot formation. They affect both factor Xa within the blood and within a preexisting clot. They do not affect platelet aggregation.

How is the effect of Xarelto measured in the lab?

The effect of XARELTO can be measured if the assay is standardized for oral anticoagulants. 25 Unlike PT and activated partial thromboplastin time (aPTT), which vary depending on the thromboplastin reagent used, the results of the chromogenic assay were reproducible in a study across 9 laboratories. 26

How are factor Xa and rivaroxaban levels measured?

Inhibition of Factor Xa and plasma rivaroxaban levels are closely correlated [ 20 ]. Therefore, assays (particularly chromogenic assays) that measure inhibition of Factor Xa activity can quantify rivaroxaban plasma concentrations [ 25, 26, 31 – 33 ].

What are the effects of Xarelto on APCR?

Results from three studies have demonstrated that, at the concentrations examined, XARELTO had minimal effects on activated protein C resistance (APCR) assays. One of these studies also determined that protein S functional activity assay provided falsely normal results in XARELTO treated patients. 11-13

Is the heptest assay specific for factor Xa?

The HepTest is a relatively new assay and is not specific for factor Xa. XARELTO has been shown to prolong the HepTest clotting time in a dose-dependent fashion; 16 however, a pharmacokinetic study of XARELTO in deep vein thrombosis patients observed a paradoxical shortened clotting time with lower XARELTO concentrations (ie, <0.2 mcg/mL). 1, 16