• Paul Billoir, Virginie Barbay, Luc Marie Joly, Marielle Fresel, Marie Hélène Chrétien, and Véronique Le Cam Duchez.
• 1 Rouen University Hospital, France.
• Ann Pharmacother. 2019 Apr 1; 53 (4): 341-347.

BackgroundOral anti-Xa inhibitors have demonstrated noninferiority to vitamin K antagonists (VKAs) for the prevention of stroke in patients with atrial fibrillation and recurrent venous thromboembolism. They are associated with a decrease in major bleeding. In contrast with VKA, no coagulation monitoring is required. However, in clinical practice, determination of drug concentration is sometimes necessary.ObjectiveThe objective of this study was to evaluate a low-molecular-weight heparin (LMWH) calibrated anti-Xa assay for the quantification of rivaroxaban and apixaban plasma concentration in emergency.MethodsThe anti-Xa plasma concentration of rivaroxaban and apixaban were measured in emergency in 210 patients using STA anti-Xa liquid assay. For each plasma concentration <150 ng/mL of rivaroxaban or apixaban, an anti-Xa assay calibrated with LMWH was performed.ResultsWe demonstrated a significant correlation between LMWH anti-Xa activity and rivaroxaban ( R2 = 0.947) or apixaban ( R2 = 0.959) concentration and a significant correlation between rivaroxaban and apixaban plasma concentration ( R2 = 0.972). A LMWH anti-Xa activity <0.50 IU/mL could exclude a plasma concentration of rivaroxaban and apixaban >30 ng/mL and indicate the feasibility of invasive procedure. Conclusion and Relevance: In the absence of a specific test, LMWH-calibrated anti-Xa assay could be used to determine the presence and evaluate the plasma concentration of oral anti-Xa inhibitors. However, these initial findings require confirmation using other chromogenic calibrated oral anti-Xa assays.

38 keywords...

hide…