Subscribe to RSS
Clinical laboratory measurement of direct factor Xa inhibitors: Anti-Xa assay is preferable to prothrombin time assayFinancial support:This study was sponsored by Bristol-Myers Squibb and Pfizer Inc.
28 May 2010
Accepted after major revision: 12 August 2010
24 November 2017 (online)
Apixaban and other factor Xa (FXa) inhibitors are in late-stage clinical development for prevention and treatment of thromboembolic diseases. Although routine monitoring will not be required, in certain situations assessment of drug level may be helpful. This study evaluated the suitability of commercially available prothrombin time/international normalised ratio (PT/INR) and anti-FXa activity assays to measure FXa inhibitors in plasma. Twelve PT (ISI 0.89ﺹ1.88) and three anti-Xa assays were evaluated in vitro using human plasma spiked with four FXa inhibitors (0ﺹ2,000 ng/ml). Assay variability and correlation with drug plasma exposure were evaluated in patients with venous thromboembolism (VTE) treated with apixaban. All FXa inhibitors prolonged PT; however, assay sensitivity was dependent on thromboplastin reagents used and FXa inhibitors tested. To achieve a doubling of PT, the concentration of each FXa inhibitor varied 2.6- to 8-fold between thromboplastin reagents. The rank order of a FXa inhibitor’s effect on PT ratio varied across thromboplastin reagents. Conversion to INR increased variability. Different anti-Xa assays showed different dynamic ranges for each FXa inhibitor; however, their rank order was consistent. For apixaban, the dynamic range of <7.8–240 ng/ml, and inter- and intra-assay precision of <6% coefficient of variation by Rotachrom assay appeared suitable for the anticipated apixaban plasma concentrations with 2.5 and 5 mg bid clinical doses. The stronger correlation between apixaban plasma concentration and anti-Xa activity (r2 = 0.88–0.89) compared with PT/INR (r2 = 0.36) in patients undergoing VTE treatment suggested that anti-Xa activity was the better indicator of apixaban plasma concentrations.
KeywordsApixaban - factor Xa inhibitor - prothrombin time - international normalised ratio - anti-Xa activity
* Formerly employed by Bristol-Myers Squibb, New Jersey, United States; Current affiliation: Pharmaceutical Consultant, Pennington, New Jersey, United States.
- 1 Hirsh J, Fuster V, Ansell J. et al. American Heart Association/American College of Cardiology foundation guide to warfarin therapy. Circulation 2003; 107: 1692-1711.
- 2 Hirsh J, Anand SS, Halperin JL. et al. American Heart Association.. AHA Scientific Statement: guide to anticoagulant therapy: heparin: a statement for healthcare professionals from the American Heart Association. Arterioscler Thromb Vasc Biol 2001; 21: E9-9.
- 3 Schulman S, Beyth RJ, Kearon C. et al. Hemorrhagic complications of anticoagulant and thrombolytic treatment: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133 (Suppl. 06) 257S-298S.
- 4 Hirsh J, O’Donnell M, Eikelboom JW. Beyond unfractionated heparin and warfarin: current and future advances. Circulation 2007; 116: 552-560.
- 5 Ho SH, Wu JK, Hamilton DP. et al. An assessment of published pediatric dosage guidelines for enoxaparin: a retrospective review. J Pediatr Hematol Oncol 2004; 26: 561-566.
- 6 Bates SM, Greer IA, Pabinger I. et al. Venous thromboembolism, thrombophilia, antithrombotic therapy, and pregnancy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133 (Suppl. 06) 844S-886S.
- 7 Nutescu EA, Spinler SA, Wittkowsky A. et al. Low-molecular-weight heparins in renal impairment and obesity: available evidence and clinical practice recommendations across medical and surgical settings. Ann Pharmacother 2009; 43: 1064-1083.
- 8 Khoo CW, Tay KH, Shantsila E. et al. Novel oral anticoagulants. Int J Clin Pract 2009; 63: 630-641.
- 9 Spyropoulos AC. Brave new world: current and future use of novel anticoagulants. Thromb Res 2008; 123 (Suppl. 01) S29-35.
- 10 Lassen MR, Raskob GE, Gallus A. et al. Apixaban or enoxaparin for thromboprophylaxis after knee replacement. N Engl J Med 2009; 361: 594-604.
- 11 Lassen MR, Raskob GE, Gallus A. et al. Apixaban versus enoxaparin for thromboprophylaxis after knee replacement (ADVANCE-2): a randomised double-blind trial. Lancet 2010; 375: 807-815.
- 12 Study of an investigational drug for the prevention of thrombosis-related events following hip replacement surgery. Available at: http://clinicaltrials.gov/ct2/show/NCT00423319?term=apixaban&rank=13. Accessed April 21, 2010.
- 13 Frost C, Yu Z, Nepal S. et al. Apixaban, an oral, direct factor Xa inhibitor: single-dose safety, pharmacokinetics and pharmacodynamics in healthy subjects. J Thromb Haemost. 2007 5 (Suppl 1): Abstract P-M-665.
- 14 Frost C, Yu Z, Moore K. et al. Apixaban, an oral factor Xa inhibitor: multiple-dose safety, pharmacokinetics and pharmacodynamics in healthy subjects. J Thromb Haemost. 2007 5 (Suppl 1): Abstract P-M-664.
- 15 Yamahira N, Imai Y, Yu Z. et al. A placebo-controlled, ascending multiple-dose study to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of apixaban in healthy Japanese subjects. Can J Clin Pharmacol 2008; 15: e719. Abstract 637.
- 16 Wong PC, Crain EJ, Xin B. et al. Apixaban, an oral, direct and highly selective factor Xa inhibitor: in vitro, antithrombotic and antihemostatic studies. J Thromb Haemost 2008; 6: 820-829.
- 17 Xarelto. Summary of Product Characteristics. Berlin, Germany: Bayer Schering Pharma AG; 2009
- 18 Samama MM, Martinoli J-L, LeFlem L. et al. Assessment of laboratory assays to measure rivaroxaban- an oral, direct factor Xa inhibitor. Thromb Haemost 2010; 103: 815-825.
- 19 van Ryn J, Stangier J, Haertter S. et al. Dabigatran etexilate- a novel, reversible, oral direct thrombin inhibitor: interpretation of coagulation assays and reversal of anticoagulant activity. Thromb Haemost 2010; 6: 1116-1127.
- 20 Quan ML, Lam PYS, Han Q. et al. Discovery of 1-(3′-aminobenzisoxazol-5′-yl)-3-trifluoromethyl-N-[2-fluoro-4–[(2′-dimethylaminomethyl)imidazol-1-yl]phenyl]-1H-pyrazole-5-carboxyamide hydrochloride (razaxaban), a highly potent, selective, and orally bioavailable factor Xa inhibitor. J Med Chem 2005; 48: 1729-1744.
- 21 Procedures for Validation of INR and Local Calibration of PT/INR Systems; Approved Guideline. Clinical Laboratory Standards Institute (CLSI) document H54-A 2005. CLSI, Wayne, PA 19087.
- 22 Botticelli Investigators, Writing Committee. Buller H, Deitchman D. et al. Efficacy and safety of the oral direct factor Xa inhibitor apixaban for symptomatic deep vein thrombosis. The Botticelli DVT dose-ranging study. J Thromb Haemost 2008; 6: 1313-1318.
- 23 Centers for Medicare and Medicaid Services (CMS) and Clinical Laboratory Improvement Amendment of 1988 (CLIA ’88). Available at: http://www.cms.hhs.gov/clia/03_Interpretive_Guidelines_for_Laboratories.asp. Accessed April 21, 2010.
- 24 van Geest-Daalderop JH, Hutten BA, Péquériaux NC. et al. The influence on INRs and coagulation factors of the time span between blood sample collection and in-take of phenprocoumon or acenocoumarol: consequences for the assessment of the dose. Thromb Haemost 2007; 4: 738-746.
- 25 Gerotziafas GT, Dupont C, Spyropoulos AC. et al. Differential inhibition of thrombin generation by vitamin K antagonists alone and associated with low-molecular-weight heparin. Thromb Haemost 2009; 1: 42-48.
- 26 Graff J, Picard-Willems B, Harder S. Monitoring effects of direct FXa-inhibitors with a new one-step prothrombinase-induced clotting time (PiCT) assay: comparative in vitro investigation with heparin, enoxaparin, fondaparinux and DX 9065a. Int J Clin Pharmacol Ther 2007; 4: 237-243.
- 27 Paccaly A, Ozoux ML, Chu V. et al. Pharmacodynamic markers in the early clinical assessment of otamixaban, a direct factor Xa inhibitor. Thromb Haemost 2005; 94: 1156-1163.
- 28 Kubitza D, Becka M, Voith B. et al. Safety, pharmacodynamics, and pharmacokinetics of single doses of BAY 59–7939, an oral, direct factor Xa inhibitor. Clin Pharmacol Ther 2005; 78: 412-421.
- 29 Tobu M, Iqbal O, Hoppensteadt D. et al. Anti-Xa and anti-IIa drugs alter international normalized ratio measurements: potential problems in the monitoring of oral anticoagulants. Clin Appl Thromb Hemost 2004; 10: 301-309.
- 30 College of American Pathologists.. Surveys 2008 CGS4-B Participant Summary. Northfield, IL: College of American Pathologists; 2008
- 31 McGlasson DL, Kaczor DA, Krasuski RA. et al. Effects of pre-analytical variables on the anti-activated factor X chromogenic assay when monitoring unfractionated heparin and low molecular weight heparin anticoagulation. Blood Coagul Fibrinolysis 2005; 16: 173-176.
- 32 Smogorzewska A, Brandt JT, Wayne LC. et al. Effect of fondaparinux on coagulation assays. Results of College of American Pathologists Proficiency Testing. Arch Pathol Lab Med 2006; 130: 1605-1611.