• Krzysztof Chojnowski, Tomasz Górski, Marta Robak, and Jacek Treliński.
• Department of Hematology, Medical University of Lodz, Poland.
• Adv Clin Exp Med. 2015 Nov 1; 24 (6): 995-1000.

BackgroundRivaroxaban (Xarelto) does not require routine coagulation monitoring; however, in certain clinical situations (overdose, drug accumulation, urgent surgery) measurement of its plasma concentration is highly recommended. Currently, there is no single hemostasis test that shows a direct correlation between rivaroxaban plasma levels and anticoagulant efficacy.ObjectivesThis study was intended to assess the value of ROTEM in determining rivaroxaban administration.Material And MethodsThirteen patients with venous thromboembolism and 13 healthy volunteers were compared with regard to certain ROTEM parameters and anti-FXa activity. The tests were done before the administration of 20 mg rivaroxaban (i.e. 24 h after previous administration) and 2.5 h afterwards.ResultsThe study group demonstrated residual activity of rivaroxaban in plasma (20 ± 11.3 ng/mL) 24 h following the previous administration, which did not cause marked changes in clotting assays compared to controls. In the group, 2.5 h after rivaroxaban administration, prolongation of PT (PTratio 1.51 ± 0.22), APTT (APPTratio: 1.30 ± 0.14) and ROTEM CT (CTratio - EXTEM: 2.45 ± 1.06, CTratio -Intem1.32 ± 0.21) were observed. The cut-off values for particular tests were created to determine if the patient had achieved desirable anticoagulant effect after rivaroxaban administration. The mean anti-FXa values were significantly lower in patients before rivaroxaban dosing than after.ConclusionsPT demonstrated better diagnostic value than APTT in rivaroxaban administration. The ROTEM clotting time (CT) according to EXTEM may be used to determine the anticoagulation effect of rivaroxaban, but is not sensitive enough to measure the residual activity of this drug.

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