What question did this study set out to answer?

To determine the impact of the direct thrombin inhibitor argatroban on INR, aPTT, and factor X during warfarin co-administration to guide INR interpretation during combined therapy.

January 1, 2001Thrombosis and Haemostasis

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

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Why the study?

Does argatroban predictably affect INR in subjects receiving warfarin?

Population

24 subjects receiving warfarin and argatroban

Comparison

Argatroban co-administered with warfarin vs Warfarin monotherapy

Design

Cohort

Follow-up

11 days

Authors

TMTurlough MontagueRoyal North Shore Hospital

Discussion

Member takes

Implication

Supports INR prediction at low-dose argatroban in warfarin overlap; hypothesis-generating and requires prospective validation before practice change.

Key Points

To determine the impact of the direct thrombin inhibitor argatroban on INR, aPTT, and factor X during warfarin co-administration to guide INR interpretation during combined therapy.
Assessed 24 subjects administered oral warfarin (7.5 mg on day 1; 3-6 mg/day on days 2-10) and argatroban infusions (1-4 µg/kg/min over 5 hours daily on days 1-11).
Measured coagulation parameters daily immediately prior to argatroban infusion (warfarin monotherapy) and at the end of the infusion (co-therapy).
Co-therapy INR increased linearly with monotherapy INR, dependent on argatroban dose and the specific thromboplastin reagent used, while aPTT lengthened dose-dependently.
Prediction errors for monotherapy INR were ≤±0.4 at argatroban doses of 1-2 µg/kg/min, but expanded to ≥±1.0 at higher doses.
No major bleeding complications occurred despite co-therapy INR values exceeding 7, with functional factor X activity remaining ≥37% of normal.

Structured PICO

Does argatroban predictably affect INR in subjects receiving warfarin?

Population

24 subjects receiving warfarin and argatroban

Intervention

Argatroban (1-4 microg/kg/min over 5 h, days 1-11) co-administered with warfarin (7.5 mg, day 1; 3-6 mg/day, days 2-10)

Comparator

Warfarin monotherapy (prior to argatroban infusion)

Outcome

International Normalized Ratio (INR), activated partial thromboplastin time (aPTT) and functional factor Xsurrogate

Argatroban at doses ≤2 microg/kg/min has a predictable effect on INR during warfarin co-therapy, allowing for reliable prediction of oral anticoagulation levels.

Cite This Study

Turlough Montague (2001) studied this question.

synapsesocial.com/papers/6a7f34abda2615c795b3aa92 https://doi.org/10.1055/s-0037-1615601

Topics

Anticoagulation in AF

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Implication

Supports INR prediction at low-dose argatroban in warfarin overlap; hypothesis-generating and requires prospective validation before practice change.

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

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Topics

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

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Topics

Also Consider