Laboratory measurements of the oral direct factor Xa inhibitor edoxaban: comparison of prothrombin time, activated partial thromboplastin time, and thrombin generation assay.

OBJECTIVES: Edoxaban, an oral direct factor Xa inhibitor, does not require routine monitoring. However, assessment of the anticoagulant effects may be required in certain situations.
METHODS: We investigated the effects of edoxaban on prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin generation using human platelet-poor plasma (PPP) or platelet-rich plasma (PRP).
RESULTS: Edoxaban concentration-dependently prolonged PT and aPTT. There was a considerable variation in the magnitude of PT prolongation among the reagents used. The variability in aPTT prolongation among the reagents was smaller than that of PT. Edoxaban concentration-dependently inhibited thrombin generation, with a more potent effect seen in PPP than in PRP. Thrombin generation assay was three times more sensitive to edoxaban than PT and aPTT.
CONCLUSIONS: PT had disadvantages of a large variability among different PT reagents. aPTT could be used as a conventional and convenient test with a smaller variation among reagents. Thrombin generation was the most sensitive assay. Copyright© by the American Society for Clinical Pathology.