A low-molecular weight heparin-calibrated anti-factor Xa assay provided comparable apixaban and rivaroxaban concentrations (<100 ng/mL) to drug-calibrated methods when compared with LC-MS/MS.
Can an LMWH-calibrated anti-factor Xa assay accurately estimate the concentration of apixaban and rivaroxaban compared to drug-calibrated assays and LC-MS/MS?
An LMWH-calibrated anti-factor Xa assay can provide a rapid and widely available method to estimate apixaban and rivaroxaban concentrations in acute settings.
INTRODUCTION: Direct oral anticoagulant (DOAC)-inhibiting factor Xa (FXa-DOAC) are being increasingly used as prophylaxis of venous thromboembolism and for prevention of stroke in patients with atrial fibrillation. In contrast to vitamin K antagonists, DOACs do not require monitoring in general. However, it is sometimes of value in the acute setting, for instance when considering a reversal agent in uncontrolled bleeding in patients on DOAC. METHODS: We evaluated if a low-molecular weight heparin (LMWH)-calibrated anti-factor Xa assay could be used to estimate FXa-DOAC concentration in the concentration range <100 ng/mL by spiking known concentrations of FXa-DOAC and from those result calculate the FXa-DOAC concentration from the response of the LMWH assay. This procedure was then evaluated by comparing the result with a drug-calibrated chromogenic assay and liquid chromatography tandem mass spectrometry (LC-MS/MS) on clinical plasma samples from patients treated with apixaban or rivaroxaban. RESULTS: Although the measuring range was narrower for the LMWH-calibrated assay, concentrations recalculated from the LMWH assay was comparable with those measured by the drug-calibrated method when compared with LC-MS/MS. CONCLUSION: We suggest that an LMWH-calibrated anti-factor Xa assay can be used after characterization of the response of FXa-DOACs to give guidance on the concentration of apixaban and rivaroxaban. Shorter turnaround time than LC-MS/MS and the greater availability than drug-calibrated chromogenic assays could make this a valuable option in the acute setting.
Horn et al. (Wed,) conducted a other in Patients treated with apixaban or rivaroxaban. Low-molecular weight heparin-calibrated anti-factor Xa assay vs. Drug-calibrated chromogenic assay and LC-MS/MS was evaluated on FXa-DOAC concentration estimation. A low-molecular weight heparin-calibrated anti-factor Xa assay provided comparable apixaban and rivaroxaban concentrations (<100 ng/mL) to drug-calibrated methods when compared with LC-MS/MS.