Comparison of Commercial LowMolecularWeight Heparin and Homemade Anti-Xa Calibrators to aCommercial Specific Anti-Xa Calibrator for Plasma Rivaroxaban Quantification by Anti-Xa Oral Anticoagulant Plasma Concentration Chromogenic Assay.

Abstract

The main concern about measuring the concentration of rivaroxaban by anti-Xa assay in some laboratories is the lack of a commercial specific calibrator in emergencies. Therefore, this study aimed at providing a homemade anti-Xa calibrator and commercial lowmolecularweight heparin (LMWH) anti-Xa calibrator. The anti-Xa plasma concentration of rivaroxaban was measured in 70 patients using a commercial specific anti-Xa calibrator, a commercial LMWH anti-Xa calibrator, and a homemade anti-Xa calibrator. We demonstrated a significant correlation and agreement (P <.001) between LMWH-calibrated anti-Xa and the commercial specific calibrator. Asignificant correlation (P <.001) was found between homemade calibrated anti-Xa made by normal pooled plasma and that calibrated with a commercial specific drug. The nonspecific homemade and LMWH calibrators had excellent agreement (P <.001) and can be used interchangeably. Our data showed that for estimating rivaroxaban concentrations, the LMWH calibrator could be used as an alternative calibrator in the anti-Xa assay.