Six anti-Xa assays not supplemented with antithrombin showed good concordance with HPLC-UV for quantifying apixaban and rivaroxaban, with bias ranging from -26.9 to 22.3 ng/mL for apixaban.
Observational (n=251)
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Are chromogenic anti-Xa assays and HPLC-UV reliable for quantifying apixaban and rivaroxaban levels in treated patients?
Anti-Xa assays not supplemented with antithrombin and HPLC-UV are reliable methods for quantifying apixaban and rivaroxaban levels in clinical practice.
INTRODUCTION: To measure direct factor Xa inhibitor (apixaban, edoxaban, rivaroxaban) concentrations, dedicated chromogenic anti-Xa assays are recommended as suitable methods to provide rapid drug quantification. Moreover, the high-performance liquid chromatography with ultraviolet detection (HPLC-UV) is reported as a reliable quantitative technique. We investigated seven anti-Xa assays and an HPLC-UV method for measurement of apixaban and rivaroxaban levels in patients enrolled in the START-Register. METHODS: A total of 127 apixaban and 124 rivaroxaban samples were tested by HPLC-UV and the following anti-Xa assays: Biophen DiXaI and Heparin LRT (Hyphen BioMed), Berichrom and Innovance Heparin (Siemens), STA-Liquid Anti-Xa (Stago Diagnostics), Technochrom anti-Xa (Technoclone), and HemosIL Liquid Anti-Xa (Werfen). Each method was performed in one of the participating laboratories: Bologna, Cremona, Florence, and Padua. RESULTS: Our data confirmed the overestimation of apixaban and rivaroxaban levels by the antithrombin-supplemented anti-Xa method (Berichrom). Performances and reproducibility of the six anti-Xa assays not supplemented with antithrombin and the HPLC-UV method were good, with limits of quantification from 8-39 ng/mL (apixaban) and 15-33 ng/mL (rivaroxaban). The six chromogenic methods showed good concordances with the quantitative HPLC-UV bias: -26.9-22.3 ng/mL (apixaban), -11.3-18.7 ng/mL (rivaroxaban). Higher bias and wider range between limits of agreement were observed at higher concentrations 200 ng/mL: bias -42.2-36.8 ng/mL (apixaban) and -20.1-68.9 ng/mL (rivaroxaban). CONCLUSION: Overall, the anti-Xa assays not supplemented with antithrombin and the HPLC-UV method proved to be suitable for apixaban and rivaroxaban quantification.
Cini et al. (Mon,) conducted a observational in Patients treated with apixaban or rivaroxaban (n=251). Chromogenic anti-Xa assays vs. HPLC-UV method was evaluated on Concordance and bias between anti-Xa assays and HPLC-UV. Six anti-Xa assays not supplemented with antithrombin showed good concordance with HPLC-UV for quantifying apixaban and rivaroxaban, with bias ranging from -26.9 to 22.3 ng/mL for apixaban.