Thromb Haemost 2001; 85(03): 435-440
DOI: 10.1055/s-0037-1615601
Review Article
Schattauer GmbH

Interpreting the International Normalized Ratio (INR) in Individuals Receiving Argatroban and Warfarin

Authors

  • S.B. Sheth

    1   SmithKline Beecham Pharmaceuticals, Presbyterian Medical Center, University of Pennsylvania Health System, Philadelphia, PA, and Texas Biotechnology Corporation (as consultant), Houston, TX, USA
  • R.A. DiCicco

    1   SmithKline Beecham Pharmaceuticals, Presbyterian Medical Center, University of Pennsylvania Health System, Philadelphia, PA, and Texas Biotechnology Corporation (as consultant), Houston, TX, USA
  • M.J. Hursting

    1   SmithKline Beecham Pharmaceuticals, Presbyterian Medical Center, University of Pennsylvania Health System, Philadelphia, PA, and Texas Biotechnology Corporation (as consultant), Houston, TX, USA
  • T. Montague

    1   SmithKline Beecham Pharmaceuticals, Presbyterian Medical Center, University of Pennsylvania Health System, Philadelphia, PA, and Texas Biotechnology Corporation (as consultant), Houston, TX, USA
  • D.K. Jorkasky

    1   SmithKline Beecham Pharmaceuticals, Presbyterian Medical Center, University of Pennsylvania Health System, Philadelphia, PA, and Texas Biotechnology Corporation (as consultant), Houston, TX, USA
Weitere Informationen

Publikationsverlauf

Received 24. Juli 2000

Accepted after resubmission 31. Oktober 2000

Publikationsdatum:
08. Dezember 2017 (online)

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Summary

The effects of argatroban, a direct thrombin inhibitor, on the International Normalized Ratio (INR), activated partial thromboplastin time (aPTT) and functional factor X during warfarin co-administration were established to provide means to interpret INRs during argatroban/warfarin co-therapy. Twenty-four subjects receiving warfarin (7.5 mg, day 1; 3-6 mg/day, days 2-10) and argatroban (1-4 μg/kg/min over 5 h, days 1-11) were assessed daily for these coagulation parameters prior to argatroban infusion (warfarin “monotherapy”) and at its conclusion (“co-therapy”). Argatroban increased aPTTs dose-dependently. Co-therapy INR increased linearly with monotherapy INR, with slope sensitive to argatroban dose and thromboplastin used. Prediction errors for monotherapy INRs were ≤± 0.4 for argatroban 1-2 μg/kg/min but ≥± 1.0 for higher doses. Despite co-therapy INRs >7, no major bleeding occurred. Factor X remained ≥37% of normal. Therefore, the predictable effect of argatroban (≤ 2 mg/kg/min only) on INRs during warfarin co-therapy allows for reliable prediction of the level of oral anticoagulation.