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Coagulation laboratory testing in patients treated with argatroban
J M Walenga1, A R Fasanella, O Iqbal
1Department of Thoracic & Cardiovascular Surgery, Loyola University Medical Center Maywood, Illinois 60153, USA.
Seminars in Thrombosis and Hemostasis
|June 5, 1999
Summary
Monitoring argatroban requires specific laboratory tests. Activated partial thromboplastin time (aPTT) and activated clotting time (ACT) can monitor argatroban, but Ecarin clotting time (ECT) offers better accuracy and less interference.
Area of Science:
- Clinical Chemistry
- Hematology
- Pharmacology
Background:
- Argatroban is a direct thrombin inhibitor used clinically.
- Coagulation laboratory testing presents challenges in patients receiving argatroban.
- Accurate drug monitoring and assessment of coagulation status are crucial.
Purpose of the Study:
- To identify appropriate laboratory methods for monitoring argatroban therapy.
- To investigate the interference of argatroban in various coagulation assays.
- To report challenges in coagulation testing during argatroban treatment.
Main Methods:
- Evaluation of activated partial thromboplastin time (aPTT) and activated clotting time (ACT) for argatroban monitoring.
- Assessment of Ecarin clotting time (ECT) for drug level assessment.
- Utilization of chromogenic assays for direct argatroban quantification and factor level determination.
- Investigation of High-Performance Liquid Chromatography (HPLC) for argatroban and metabolite quantification.
- Analysis of argatroban interference in assays for INR, fibrinogen, factor levels, and protein C.
Main Results:
- aPTT and ACT effectively monitored low and high argatroban doses, but showed system variability.
- ECT demonstrated utility for monitoring both low and high argatroban levels with reduced interference.
- Chromogenic antithrombin assay and HPLC assay directly quantified argatroban and its metabolites.
- Argatroban synergistically interfered with INR in patients on oral anticoagulants.
- Routine functional assays for fibrinogen, factor levels, and protein C were unreliable due to argatroban inhibition; chromogenic assays provided accurate results.
Conclusions:
- Specific laboratory assays are necessary for reliable argatroban monitoring and to assess coagulation status in treated patients.
- Ecarin clotting time (ECT) and chromogenic assays offer advantages over traditional clot-based methods.
- Argatroban interference affects standard coagulation tests, necessitating alternative methods for accurate assessment.
- Findings are likely applicable to other direct thrombin inhibitors.