Comparison of the anticoagulant response of a novel fluorogenic anti-FXa assay with two commercial anti-FXa chromogenic assays

Laboratory Monitoring of Low-Molecular-Weight Heparin and Fondaparinux

“…While anti-Xa assays are considered the gold standard, point-of-care tests and assays that use whole blood may be advantageous in some situations. 2,12,13 Certain patient populations may benefit from LMWH and fondaparinux monitoring, including pregnant patients, children, obese patients, and patients with renal impairment. 1,22,25 However, therapeutic LMWH and fondaparinux ranges may not correlate with clinical outcomes, so the need for testing should be carefully evaluated and results should be interpreted with caution.…”

“…The chromogenic anti-Xa assay is currently the gold standard for monitoring LMWH and fondaparinux therapy. 1,2 The anti-Xa assay should not be confused with the factor X activity assay or the chromogenic factor X assay, as these measure the activity of endogenous factor X and not activated factor X (factor Xa), while the anti-Xa assay measures the ability of the patient's plasma to inhibit exogenous factor Xa. 3 There are several commercially available anti-Xa assay kits that use different substrates to measure plasma anti-Xa activity.…”

“…One advantage of the fluorogenic assay over the chromogenic assay is its ability to test opaque samples, such as platelet-rich plasma and whole blood samples, as it does not rely on optical density readings, which require relatively clear samples. 2 When measuring LMWH and fondaparinux anti-Xa levels, peak as opposed to trough levels have been shown to correlate better with safety and efficacy (►Table 1). 6 To obtain a peak measurement, blood for LMWH levels should be drawn 4 hours after subcutaneous injection, and blood for fondaparinux levels should be drawn 3 hours after injection.…”

Development of Bioanalytical Assays for Variegin, A Peptide-Based Bivalent Direct Thrombin Inhibitor

“…Apart from LC-MS/MS, activity-based assays such as chromogenic substrate assays and coagulation assays have also been developed for biomonitoring and PK analysis of therapeutics, particularly antithrombotic drugs [17]. Some examples include the Hemoclot ® (Aniara, Inc., OH, USA) dilute thrombin time assay for dabigatran and anti-Xa activity assay for heparin, which can be used to determine the plasma concentration of drugs [18,19]. Compared with LC-MS assays, these activity-based assays have the advantage of being suitable for use by nonspecialist laboratories and configuration into point-of-care tests.…”