DP-Filter, a Rapid and Ergonomic Device to Remove Direct Thrombin Inhibitor Argatroban from Plasma for Routine Hemostasis Tests

Argatroban is a direct thrombin inhibitor (DTI) used as an effective alternative anticoagulation therapy in patients suffering from heparin-induced thrombocytopenia (HIT), a serious and potentially life-threatening condition. One of its limitations is its need to be administered intravenously in a continuous manner because of its short half-life in patients without hepatic dysfunction. Thus, a transition towards another long-term anticoagulation therapy, for instance with anti-vitamin K drugs, is usually recommended once HIT is no longer acute and platelet count is stabilized. However, during the transition, remaining plasma levels of argatroban may interfere with hemostasis testing used to monitor the patient response to new anticoagulation drug dosage. The DP-Filter is a functional and user-friendly device used for plasma preparation. This device was already proven effective to substitute the second centrifugation step for platelet poor plasma preparation and to remove direct oral anticoagulants from citrated plasma.

We aimed to assess the efficacy of the DP-Filter to remove argatroban from human plasma samples in a fast, practical, and ergonomic way. Argatroban was spiked in human normal pooled plasma (NPP) samples at six concentrations (0.0 [Hepes buffer], 0.1, 0.25, 0.5, 1.0 and 2.0 µg/mL). NPP samples were provided by NAB-X biobank from the University of Namur (Belgium) and were collected on March 23^rd, 2022. NPP samples were collected from 8 men and 24 women, with mean age of 22 years old (min = 19 ; max = 48) and mean BMI of 23 (min = 19 ; max = 29). Blood samples were collected in accordance with the Declaration of Helsinki following approval by the Ethical Committee of the CHU UCL Namur (Yvoir, Belgium) under the approval number B03920096633.

Argatroban levels were assessed in duplicates in spiked NPP samples before and after filtration with DP-Filter using argatroban-calibrated STA-ECAII testing (Argatroban Plasma Calibrator from Hyphen BioMed). Increasing concentrations of argatroban were measured in non-filtered spiked NPP samples while filtration through DP-Filter reduced argatroban levels close to 0.0 µg/mL, even when spiked concentration was as high as 2.0 µg/mL (Figure 1).

Among routine coagulation tests, the activated partial thromboplastin time (aPTT) can be used to assess the anticoagulant effect of DTI. Thus, aPTT was used as a sensitive clotting test to assess the performance of the DP-filter to restore the baseline (i.e. in absence of argatroban) clotting capacity of the plasma. This was determined in duplicates using STA-PTT A5 testing with silica as activator. Filtration through DP-Filter was able to restore normal aPTT values, even at the highest tested argatroban concentration (i.e. 2.0 µg/mL). Similar results were obtained on filtered and non-filtered NPP samples spiked with 0.0 µg/mL of argatroban, confirming the absence of impact of DP-Filter on aPTT testing itself (Figure 2).

Altogether, our results show that DP-Filter is an effective, rapid and ergonomic tool to remove argatroban from plasma. It can be used in clinical routine to remove the interference of argatroban with hemostasis tests and therefore avoid false positive or false negative results and unnecessary testing. It also emerges as a solution to ease the monitoring of the transition from patient anticoagulation with argatroban to another anticoagulation therapy such as anti-vitamin K drugs. This might be of particular importance in patients suffering from HIT.

Donis:QUALIblood S.A.: Current Employment. Bouvy:QUALIblood S.A.: Current Employment. Modaffari:QUALIblood S.A.: Current Employment. Vandeputte:QUALIblood S.A.: Current Employment. Carlo:Diagnostica Stago S.A.S.: Current Employment. Douxfils:QUALIblood S.A.: Other: CEO.