Monitoring of Anticoagulant Effects of Direct Thrombin Inhibitors

ABSTRACT

Monitoring of direct thrombin inhibitors with the activated partial thromboplastin time (aPTT) is limited by poor linearity and reproducibility. Recently, direct prothrombin activation methods have been developed for coagulation analysis: ecarin clotting time (ECT) and prothrombinase-induced clotting time (PiCT). Laboratory monitoring of the direct thrombin inhibitors lepirudin, argatroban, and melagatran was analyzed and compared with monitoring unfractionated heparin (UFH).

Plasma samples of six healthy donors were spiked with lepirudin and argatroban extending to 3000 ng/mL, melagatran extending to 1000 ng/mL, and UFH up to 0.48 IU/mL. Clotting times of aPTT (two reagents), ECT, PiCT, and prothrombin time were determined in a KC 10, a micro instrument.

At 3000 ng/mL ECT values were 339.1 ± 25.0 seconds with lepirudin and 457.5 ± 29.5 seconds with argatroban. ECT was 586.0 ± 38.2 seconds with 1000 ng/mL melagatran. The PiCT method provided clotting times of 137.0 ± 8.4 seconds with UFH, 128.0 ± 23.4 seconds with lepirudin, and 151 ± 23.9 seconds with argatroban, and 153.5 ± 9.9 seconds with melagatran, with the concentrations mentioned.

ECT is more sensitive to therapeutic drug concentration ranges than aPTT (prolongations of 3-7 versus 2-3). PiCT yields comparable results with direct thrombin inhibitors and UFH. This method could therefore be suitable for monitoring both drug groups.

KEYWORDS

Thrombin inhibitors - ecarin clotting time - prothrombinase-induced clotting time - hirudin - argatroban - melagatran

REFERENCES

• 1 Hyers T M, Agnelli G, Hull R. Antithrombotic therapy for venous thromboembolic disease.  Chest . 1998;  114 561-578
• 2 Levine M, Gent M, Hirsh J. A comparison of low-molecular-weight heparin administered primarily at home with unfractionated heparin administered in the hospital for proximal deep-vein-thrombosis.  N Engl J Med . 1996;  334 677-681
• 3 Koopman M MW, Prandoni P, Piovella F. Treatment of patients with proximal-vein thrombosis with intravenous unfractionated heparin in hospital compared with subcutaneous low-molecular-weight heparin out of hospital or with early discharge.  N Engl J Med . 1996;  334 682-687
• 4 Simonneau G, Sors H, Charbonnier B, for the THÉSÉE Study Group et al. A comparison of low-molecular-weight heparin with unfractionated heparin for acute pulmonary embolism.  N Engl J Med . 1997;  337 663-669
• 5 The Columbus Investigators. Low-molecular-weight heparin in the treatment of patients with venous thromboembolism.  N Engl J Med . 1997;  337 657-662
• 6 Weitz J I. Low molecular weight heparins.  N Engl J Med . 1997;  337 688-698
• 7 Ginsberg J S. Management of venous thromboembolism.  N Engl J Med . 1996;  335 1816-1828
• 8 Calatzis A, Spannagl M, Gempeler-Messina P. The prothrombinase-induced clotting time, a new technique for the monitoring of anticoagulants.  Haemostasis . 2000;  30(Suppl 2) 172-174
• 9 Fenyvesi T, Giese C H, Sichau-Traeger I, Harenberg J. Influence of thrombin inhibitors hirudin, argatroban, melagatran and of unfractionated heparin on the PiCT assay-effect of oral anticoagulation.  Ann Hematol . 2002;  Suppl (Abst)
• 10 Thomson J M, Taberner D A, Poller L. Automation and prothrombin time: a United Kingdom field study of two widely used coagulometers.  J Clin Pathol . 1990;  43 679-684
• 11 Hoffmann J J, Meulendijk P N. Comparison of reagents for determining the activated partial thromboplastin time.  Thromb Haemost . 1978;  39 640-645
• 12 Refsum N, Collen D, Godal H C. Sensitivity and precision of activated partial thromboplastin time (aPTT) methods. A multicenter study.  Scand J Haematol . 1978;  20 89-95
• 13 Kritikos V G, Melhem M F. Comparison of three prothrombin time and activated partial thromboplastin time reagent systems on the MLA 700 coagulation analyzer.  Clin Lab Sci . 1993;  6 302-307
• 14 Bates S M, Weitz J I, Johnston M, Hirsh J, Ginsberg J S. Use of a fixed activated partial thromboplastin time ratio to establish a therapeutical range for unfractionated heparin.  Arch Intern Med . 2001;  161 385-391
• 15 Reed S V, Haddon M E, Denson K W. An attempt to standardize the aPTT for heparin monitoring, using the PT ISI/INR system for calibration. Results of a 13 centre study.  Thromb Res . 1994;  74 515-522
• 16 Nowak G, Bucha E. Quantitative determination of hirudin in blood and body fluids.  Semin Thromb Hemost . 1996;  22 197-202
• 17 Poetzsch B, Hund S, Madlener K, Unkrig C, Müller-Berghaus G. Monitoring of recombinant hirudin: assessment of a plasma-based ecarin clotting time assay.  Thromb Res . 1997;  86 373-383
• 18 Baumann P, Heuck C C. Simulation of the extrinsic pathway of the plasmatic clotting system.  Haemostasis . 1991;  21 329-337
• 19 Johnson B C. Post-translational carboxylation of preprothrombin.  Mol Cell Biochem . 1981;  38 77-121
• 20 Nar H, Bauer M, Schmid A. Structural basis for inhibition promiscuity of dual specific thrombin and factor Xa blood coagulation inhibitors.  Structure (Camb) . 2001;  9 29-38
• 21 Fenyvesi T, Joerg I, Harenberg J. Influence of hirudin, argatroban and melagatran on the prothrombin time and the additional effect of oral anticoagulation.  Submitted for publication.
• 22 Sheth S B, DiCicco R A, Hursting M J, Montague T, Jorkasky D K. Interpreting the international normalized ratio (INR) in individuals receiving argatroban and warfarin.  Thromb Haemost . 2001;  85 435-440
• 23 Hursting M J, Zehnder J L, Joffrion J L. The international normalized ratio during concurrent warfarin and argatroban anticoagulation: differential contributions of each agent and effects of the choice of thromboplastin used.  Clin Chem . 1999;  45 409-412
• 24 Walenga J M, Fasanella A R, Iqbal O. Coagulation laboratory testing in patients treated with argatroban.  Semin Thromb Hemost . 1999;  25(Suppl 1) 61-66
• 25 Kher A, Gouin I, Samama M M. Follow-up of the treatment by direct thrombin inhibitors: activated partial thromboplastin time or ecarin clotting time [Article in French].  Ann Biol Clin . 2000;  58 575-579
• 26 Van den Besselaar M A, Meeuwisse-Braun J, Bertina R M. Monitoring heparin therapy: relationships between the activated partial thromboplastin time and heparin assays based on ex-vivo heparin samples.  Thromb Haemost . 1990;  63 16-23
• 27 Eriksson U G, Frison L, Gustafsson D. Effect of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran (pINN, formerly H 376/95) on activated partial thromboplastin time in orthopaedic surgery patients treated to prevent deep vein thrombosis and pulmonary embolism.  Thromb Haemost . 2001;  Suppl (Abst)