Aims While antithrombin (AT)-independent inhibitors targeting thrombin or activated factor X have been assessed through clot waveform (CWA), there are no reports on assessment with respect to AT-dependent anticoagulants. The present study aims to characterise AT-dependent anticoagulants through CWA to distinguish them from AT-independent inhibitors.
Methods CWA was applied to the activated partial thromboplastin time (APTT) assay of plasma samples spiked with each of AT-dependent drugs (unfractionated heparin, enoxaparin and fondaparinux) and AT-independent drugs (rivaroxaban, apixaban, edoxaban, dabigatran, argatroban, hirudin and bivalirudin), which was performed using the CS-5100 or CN-6000 (Sysmex). The APTT-CWA data were automatically gained by the analyser program. The positive mode of clotting reaction curves was defined as the direction towards fibrin generation.
Results Regarding dose–response curves in AT-dependent anticoagulants, the maximum positive values of the first and secondary derivatives (Max1 and Maxp2, respectively) and the maximum negative values of the secondary derivative (Maxn2) seemed to drop to zero without making an asymptotic line, consistent with the irreversibility. Such a feature was observed also in hirudin, as reported previously. Notably, the symmetric property of Max1 peaks in the waveforms was distorted dose dependently in AT independent but not AT-dependent drugs. A plot of Maxp2 logarithm versus Maxn2 logarithm was linear. The slope was about 1 in AT-dependent drugs while that was more than 1 in AT-independent drugs. These features made it possible to distinguish AT-dependent and AT-independent drugs.
Conclusions The results aid in further understanding of the pharmacological aspects of anticoagulation and in screening of candidates for novel anticoagulants.
- blood coagulation
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Handling editor Mary Frances McMullin.
MW and YF contributed equally.
Contributors MW and YF designed the study, analysed and interpreted the data, and wrote the manuscript. MW conceived the study. YF and SN performed the experiments. All authors discussed the data and critically reviewed and revised the manuscript. All authors have given final approval for this version of the manuscript to be published.
Funding This work was supported by the BMS/Pfizer Japan Thrombosis Investigator Initiated Research Program (JRISTA). YF was supported by a grant from the Charitable Trust Laboratory Medicine Research Foundation of Japan.
Competing interests The BMS/Pfizer Japan Thrombosis Investigator Initiated Research Program (JRISTA), which supported this work, is administered by the companies, Bristol-Myers Squibb and Pfizer.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article.