Impact of Idarucizumab and Andexanet Alfa on DOAC Plasma Concentration and ClotPro® Clotting Time: An Ex Vivo Spiking Study in A Cohort of Trauma Patients

Specific antagonists have been developed for the reversal of direct oral anticoagulants (DOAC). We investigated the impact of these reversal agents on the plasma concentration and visco-elastic test results of dabigatran and factor Xa inhibitors. After baseline measurements of dabigatran, the plasma concentration, and the visco-elastic ClotPro® ecarin clotting time (ECA-CT), we added the reversal agent Idarucizumab in vitro and these two analyses were repeated. Likewise, the baseline plasma concentration of apixaban, edoxaban, and rivaroxaban as well as ClotPro® Russell’s viper venom test clotting time (RVV-CT) were measured and reanalyzed following Andexanet alfa spiking. We analyzed fifty blood samples from 37 patients and 10 healthy volunteers. Idarucizumab decreased the measured dabigatran plasma concentration from 323.9 ± 185.4 ng/mL to 5.9 ± 2.3 ng/mL and ECA-CT from 706.2 ± 344.6 s to 70.6 ± 20.2 s, (all, p < 0.001). Andexanet alfa decreased the apixaban concentration from 165.1 ± 65.5 ng/mL to 9.8 ± 8.1 ng/mL, edoxaban from 152.4 ± 79.0 ng/mL to 36.4 ± 19.2 ng/mL, and rivaroxaban from 153.2 ± 111.8 ng/mL to 18.1 ± 9.1 ng/mL (all p < 0.001). Andexanet alfa shortened the RVV-CT of patients with apixaban from 239.2 ± 71.7 s to 151.1 ± 30.2 s, edoxaban from 288.2 ± 65.0 s to 122.7 ± 37.1 s, and rivaroxaban from 225.9 ± 49.3 s to 103.7 ± 12.1 s (all p < 0.001). In vitro spiking of dabigatran-containing blood with Idarucizumab substantially reduced the plasma concentration and ecarin-test clotting time. Andexanet alfa lowered the concentration of the investigated factor Xa-inhibitors but did not normalize the RVV-CT. In healthy volunteers’ blood, Idarucizumab spiking had no impact on ECA-CT. Andexanet alfa spiking of non-anticoagulated blood prolonged RVV-CT (p = 0.001), potentially as a consequence of a competitive antagonism with human factor Xa.

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Viscoelastometry for detecting oral anticoagulants

Thrombosis Journal ◽

10.1186/s12959-021-00267-w ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Philipp Groene ◽

Daniela Wagner ◽

Tobias Kammerer ◽

Lars Kellert ◽

Andreas Giebl ◽

...

Keyword(s):

Healthy Volunteers ◽

Prospective Observational Study ◽

Oral Anticoagulants ◽

Plasma Concentrations ◽

Factor Xa ◽

Clotting Time ◽

Emergency Situations ◽

Tissue Plasminogen ◽

The Impact

Abstract Background Determination of anticoagulant therapy is of pronounced interest in emergency situations. However, routine tests do not provide sufficient insight. This study was performed to investigate the impact of anticoagulants on the results of viscoelastometric assays using the ClotPro device. Methods This prospective, observational study was conducted in patients receiving dabigatran, factor Xa (FXa)-inhibitors, phenprocoumon, low molecular weight heparin (LMWH) or unfractionated heparin (UFH) (local ethics committee approval number: 17–525-4). Healthy volunteers served as controls. Viscoelastometric assays were performed, including the extrinsic test (EX-test), intrinsic test (IN-test) Russel’s viper venom test (RVV-test), ecarin test (ECA-test), and the tissue plasminogen activator test (TPA-test). Results 70 patients and 10 healthy volunteers were recruited. Clotting time in the EX-test (CTEX-test) was significantly prolonged versus controls by dabigatran, FXa inhibitors and phenprocoumon. CTIN-test was prolonged by dabigatran, FXa inhibitors and UFH. Dabigatran, FXa inhibitors and UFH significantly prolonged CTRVV-test in comparison with controls (median 200, 207 and 289 vs 63 s, respectively; all p < 0.0005). Only dabigatran elicited a significant increase in CTECA-test compared to controls (median 307 vs 73 s; p < 0.0001). CTECA-test correlated strongly with dabigatran plasma concentration (measured by anti-IIa activity; r = 0.9970; p < 0.0001) and provided 100% sensitivity and 100% specificity for detecting dabigatran. Plasma concentrations (anti-XA activity) of FXa inhibitors correlated with CTRVV-test (r = 0.7998; p < 0.0001), and CTRVV-test provided 83% sensitivity and 64% specificity for detecting FXa inhibitors. Conclusions In emergency situations, ClotPro viscoelastometric assessment of whole-blood samples may help towards determining the presence and type of anticoagulant class that a patient is taking. Trial registration German clinical trials database ID: DRKS00015302.

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The effect of DOAC-Stop on lupus anticoagulant testing in plasma samples of venous thromboembolism patients receiving direct oral anticoagulants

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2018-1197 ◽

2019 ◽

Vol 57 (9) ◽

pp. 1374-1381 ◽

Cited By ~ 17

Author(s):

Michał Ząbczyk ◽

Magdalena Kopytek ◽

Joanna Natorska ◽

Anetta Undas

Keyword(s):

Venous Thromboembolism ◽

Screening Test ◽

Lupus Anticoagulant ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Activated Partial Thromboplastin Time ◽

Clotting Time ◽

The Impact ◽

Anticoagulated Patients

Abstract Background Direct oral anticoagulants (DOACs) cause false positive lupus anticoagulant (LA) results. We assessed the impact of DOAC-Stop, reversing in vitro effects of DOACs, on LA testing in anticoagulated patients. Methods We assessed 75 venous thromboembolism patients aged 44.5±14.6 years. Blood samples were collected 2–28 h since intake of DOACs, including 50 patients on rivaroxaban, 20 on dabigatran and five on apixaban. LA testing was performed at baseline and after DOAC-Stop treatment. Positive LA was defined as the normalized (patient/standard plasma clotting time) LA screening and screening (LA1)/confirmation (LA2) ratios exceeding 1.2. Results LA diluted Russell’s viper venom time (dRVVT) normalized screening test revealed abnormal results in 73 (97.3%) and activated partial thromboplastin time (APTT)-LA in 49 (65.3%) patients. In six (8%) patients, antiphospholipid syndrome (APS) was diagnosed. dRVVT LA1/LA2 was abnormal in 35 (50.7%) patients taking DOACs. The APTT ratio was normal in all studied subjects. DOAC-Stop completely removed dabigatran and reduced by 98% rivaroxaban and by 92.3% apixaban concentrations (all p<0.05). After DOAC-Stop screening dRVVT remained prolonged in 34 (49.3%) patients (p<0.001), while dRVVT LA1/LA2 was abnormal in six (8.7%) subjects, with no association with DOAC concentrations at baseline and after DOAC-Stop. The APTT-LA screening test remained prolonged in five (7.2%) patients, while the APTT LA1/LA2 ratio was normal in those subjects. DOAC-Stop did not influence LA testing in APS patients. Conclusions Application of DOAC-Stop effectively reduced plasma DOAC concentrations leading to appropriate dRVVT results in up to 97% of VTE patients.

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Andexanet alfa for reversal of factor Xa inhibitors: a critical review of the evidence

Future Cardiology ◽

10.2217/fca-2019-0038 ◽

2019 ◽

Vol 15 (6) ◽

pp. 395-404

Author(s):

Jameel Abdulrehman ◽

John W Eikelboom ◽

Deborah M Siegal

Keyword(s):

Vitamin K Antagonists ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Factor Xa ◽

Factor Xa Inhibitors ◽

Activity Levels ◽

Reversal Agents ◽

Life Threatening ◽

Andexanet Alfa ◽

Anticoagulated Patients

Direct oral anticoagulants are associated with lower rates of bleeding than vitamin K antagonists, but life-threatening bleeding still occurs. Andexanet alfa is a catalytically inactive recombinant modified human factor Xa molecule that reverses the anticoagulant effect of direct and indirect acting factor Xa inhibitors. In the ANNEXA-4 study, treatment with andexanet was associated with a 92% reduction in median anti-Xa activity levels and excellent or good hemostasis in 82% of patients presenting with serious bleeding while receiving apixaban or rivaroxaban. In this review, we discuss the burden of bleeding in anticoagulated patients and the need for reversal agents, review the mechanism of action of andexanet and critically evaluate the evidence for its efficacy and safety.

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Comparison of the Anticoagulant and Antithrombotic Effects of Synthetic Thrombin and Factor Xa Inhibitors

Thrombosis and Haemostasis ◽

10.1055/s-0038-1645198 ◽

1990 ◽

Vol 63 (02) ◽

pp. 220-223 ◽

Cited By ~ 19

Author(s):

J Hauptmann ◽

B Kaiser ◽

G Nowak ◽

J Stürzebecher ◽

F Markwardt

Keyword(s):

Factor Xa ◽

Thrombin Inhibitors ◽

Factor Xa Inhibitors ◽

Venous Stasis ◽

Clotting Time ◽

Thrombosis Model ◽

Activity Factor ◽

Antithrombotic Effects

SummaryThe anticoagulant effect of selected synthetic inhibitors of thrombin and factor Xa was studied in vitro in commonly used clotting assays. The concentrations of the compounds doubling the clotting time in the various assays were mainly dependent on their thrombin inhibitory activity. Factor Xa inhibitors were somewhat more effective in prolonging the prothrombin time compared to the activated partial thromboplastin time, whereas the opposite was true of thrombin inhibitors.In vivo, in a venous stasis thrombosis model and a thromboplastin-induced microthrombosis model in rats the thrombin inhibitors were effective antithrombotically whereas factor Xa inhibitors of numerically similar IQ value for the respective enzyme were not effective at equimolar dosageThe results are discussed in the light of the different prelequisiles and conditions for inhibition of thrombin and factor Xa in the course of blood clotting.

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Heparin is more effective than apixaban in inhibiting in vitro contact activated coagulation

European Heart Journal ◽

10.1093/ehjci/ehaa946.3776 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

M.M Engelen ◽

C Van Laer ◽

M Jacquemin ◽

C Vandenbriele ◽

K Peerlinck ◽

...

Keyword(s):

Thrombin Generation ◽

Heart Valves ◽

Thrombus Formation ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Factor Xa ◽

Coagulation Factor ◽

Mechanical Heart Valves ◽

Contact Activation

Abstract Introduction Contact of blood with artificial surfaces such as mechanical support devices, catheters, and mechanical heart valves activates the contact activation (CA) pathway of coagulation. Furthermore, recent animal data and clinical studies suggest a more important contribution of CA in pathological thrombus formation in other cardiovascular diseases. Direct oral anticoagulants (DOACs) are recommended as first-line treatment in most patients who require long-term anticoagulation. However, because DOACs directly inhibit a single downstream coagulation factor (thrombin (fXIIa) or factor Xa (fXa)), it has been suggested that their efficacy could be reduced in the presence of strong activation of the CA pathway as compared to anticoagulants that target multiple, more upstream located coagulation factors. Purpose To compare the efficacy of a DOAC (apixaban) and heparin to suppress thrombin generation in the presence of strong CA pathway activation. Methods Pooled platelet-poor plasma was spiked with either apixaban (dissolved in DMSO and PBS) or unfractionated heparin to achieve therapeutic plasma levels. SynthASil, a commercially available mixture of phospholipids and silica, was used to stimulate the CA pathway in two different dilutions (1–80 and 5–80). Downstream coagulation was accessed by Thrombin Generation Test using Thrombinoscope by Stago and associated Thrombin Calibrator (activity 640 nM). The endogenous thrombin potential (area under the thrombin generation curve; ETP), peak thrombin generation (PTG), time to peak (ttPeak) and time to start (ttStart) were accessed. Results With decreasing concentrations of apixaban, stimulation with the lower dose SynthASil reveals an increasing ETP and PTG. As expected, ttPeak and ttStart decreased. Even supratherapeutic levels of apixaban (i.e. 1120 ng/mL) could not inhibit thrombin from being generated, in striking contrast with UFH where no thrombin was formed. Using a five times higher dose of SynthASil showed comparable ETP for all concentrations of apixaban, allocated around the control value. PTG, however, slightly increased with decreasing concentrations of apixaban. ttPeak and ttStart slightly decreased. Except for the subtherapeutic UFH concentration of 0,114 IU/mL, no thrombin was generated with UFH. Conclusion UFH is more effective in inhibiting downstream thrombin generation compared to apixaban as a response to activation of the CA pathway in vitro. These findings could help explain why direct inhibitors were not able to show non-inferiority in patients with mechanical heart valves and support the development of specific CA pathway inhibitors for patients with conditions that activate the CA pathway. Thrombin generation curves Funding Acknowledgement Type of funding source: None

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Difficult Intraoperative Heparinization Following Andexanet Alfa Administration

Clinical Practice and Cases in Emergency Medicine ◽

10.5811/cpcem.2019.9.43650 ◽

2019 ◽

Vol 3 (4) ◽

pp. 390-394 ◽

Cited By ~ 2

Author(s):

C. James Watson ◽

Sara Zettervall ◽

Matthew Hall ◽

Michael Ganetsky

Keyword(s):

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Factor Xa ◽

Hemodynamic Instability ◽

The United States ◽

Major Hemorrhage ◽

Reversal Agents ◽

Abdominal Aortic ◽

United States Food ◽

Andexanet Alfa

Direct oral anticoagulants are now commonplace, and reversal agents are recently becoming available. Andexanet alfa (AnXa), approved by the United States Food and Drug Administration in 2018, is a novel decoy molecule that reverses factor Xa inhibitors in patients with major hemorrhage. We present a case of a 70-year-old man taking rivaroxaban with hemodynamic instability from a ruptured abdominal aortic aneurysm. He received AnXa prior to endovascular surgery, and intraoperatively he could not be heparinized for graft placement. Consideration should be given to the risks and benefits of AnXa administration in patients who require anticoagulation after hemorrhage has been controlled.

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Direct Oral Anticoagulants for the Treatment of Acute Venous Thromboembolism Associated with Cancer: A Systematic Review and Meta-Analysis

Thrombosis and Haemostasis ◽

10.1055/s-0040-1712098 ◽

2020 ◽

Vol 120 (07) ◽

pp. 1128-1136 ◽

Cited By ~ 8

Author(s):

Michela Giustozzi ◽

Giancarlo Agnelli ◽

Jorge del Toro-Cervera ◽

Frederikus A. Klok ◽

Rachel P. Rosovsky ◽

...

Keyword(s):

Major Bleeding ◽

Meta Analysis ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Factor Xa ◽

Factor Xa Inhibitors ◽

Patients With Cancer ◽

Randomized Controlled ◽

Recurrent Vte ◽

Acute Venous Thromboembolism

Abstract Background International guidelines have endorsed the use of edoxaban or rivaroxaban as an alternative to low-molecular-weight heparin (LMWH) for the treatment of acute venous thromboembolism (VTE) in cancer patients. Recently, a large randomized controlled trial of apixaban versus dalteparin in patients with cancer was completed. We performed an updated meta-analysis to assess the efficacy and safety of direct oral anticoagulants (DOACs) versus LMWH in patients with cancer-associated VTE. Methods MEDLINE, EMBASE, and CENTRAL (Cochrane Controlled Trials Registry) were systematically searched up to March 30, 2020 for randomized controlled trials comparing DOACs versus LMWH for the treatment of VTE in patients with cancer. The two coprimary outcomes were recurrent VTE and major bleeding at 6 months. Data were pooled by the Mantel–Haenszel method and compared by relative risk ratios (RRs) and 95% confidence intervals (CIs). Results Four randomized controlled studies (2,894 patients) comparing apixaban, edoxaban, or rivaroxaban with dalteparin were included in the meta-analysis. Recurrent VTE occurred in 75 of 1,446 patients (5.2%) treated with oral factor Xa inhibitors and in 119 of 1,448 patients (8.2%) treated with LMWH (RR 0.62; 95% CI 0.43–0.91; I 2, 30%). Major bleeding occurred in 62 (4.3%) and 48 (3.3%) patients receiving oral factor Xa inhibitors or LMWH, respectively (RR 1.31; 95% CI 0.83–2.08; I 2, 23%). Conclusion In patients with cancer-associated VTE, oral factor Xa inhibitors reduced the risk of recurrent VTE without a significantly higher likelihood of major bleeding at 6 months compared with LMWH.

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Heparin induced thrombocytopenia

Hämostaseologie ◽

10.5482/hamo-15-04-0013 ◽

2015 ◽

Vol 35 (04) ◽

pp. 372-375 ◽

Cited By ~ 1

Author(s):

N. A. Viniou ◽

P. Diamantopoulos ◽

J. Barbetseas ◽

E. A. Sanidas

Keyword(s):

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Treatment Options ◽

Factor Xa ◽

Additional Treatment ◽

Thrombin Inhibitors ◽

Factor Xa Inhibitors ◽

Clinical Aspects ◽

Heparin Induced Thrombocytopenia

SummaryHeparin induced thrombocytopenia (HIT) is a prothrombotic syndrome initiated by platelet-activating auto-antibodies with potentially devastating complications. Once the diagnosis of HIT is suspected, discontinuation of heparin and treatment with an alternative anticoagulant are mandatory. While established drugs for HIT are no longer available, parenteral factor Xa inhibitors, thrombin inhibitors and perhaps the direct oral anticoagulants provide additional treatment options. The aim of this review was to highlight the current clinical aspects regarding HIT focusing on the role of novel medications.

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Direct oral factor Xa inhibitors for the treatment of acute cancer-associated venous thromboembolism: A systematic review and network meta-analysis.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.e23156 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. e23156-e23156

Author(s):

Harry E Fuentes ◽

Robert McBane ◽

Waldemar Wysokinski ◽

Alfonso Javier Tafur ◽

Charles L. Loprinzi ◽

...

Keyword(s):

Venous Thromboembolism ◽

Major Bleeding ◽

Meta Analysis ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Indirect Comparison ◽

Factor Xa ◽

Factor Xa Inhibitors ◽

Efficacy And Safety ◽

Patients With Cancer

e23156 Background: A direct meta-analysis was performed to explore the efficacy and safety of direct oral factor Xa inhibitors with dalteparin in patients with cancer associated acute venous thromboembolism (VTE). Also, the comparative efficacy and safety of apixaban, rivaroxaban, and edoxaban was assessed with a network meta-analysis. Methods: MEDLINE, CENTRAL, and EMBASE were searched for trials comparing direct oral anticoagulants (DOACs) to dalteparin for the management of cancer associated acute VTE. A network meta-analysis using both frequentist and Bayesian methods was performed to analyze VTE recurrence, major and clinically relevant non-major bleeding (CRNMB). Results: Three randomized control trials, at low risk of bias, enrolled 1,739 patients with cancer associated VTE. Direct comparison showed a lower rate of VTE recurrence in DOAC compared to dalteparin groups (odds Ratio [OR]:0.48, 95% Confidence interval [CI]:0.24-0.96; I2:46%). Indirect comparison suggested that apixaban had greater reduction in VTE recurrence compared to dalteparin (OR: 0.10; 95% CI: 0.01–0.82), but not rivaroxaban or edoxaban. Apixaban also had the highest probability of being ranked most effective. By direct comparisons, there was an increased likelihood of major bleeding in the DOAC group compared to dalteparin (OR: 1.70; 95% CI: 1.04–2.78). CRNMB did not differ. Indirect estimates were imprecise. Subgroup analyses in gastrointestinal cancers suggested that dalteparin may have the lowest risk of bleeding whereas estimates in urothelial cancer were imprecise. Conclusions: DOACs appear to lower the risk of VTE recurrence compared to daltaparin while increasing major bleeding. Apixaban may be associated with the lowest risk of VTE recurrence compared to the other DOACs.

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Reversal of direct oral anticoagulants: a practical approach

Hematology ◽

10.1182/asheducation-2016.1.612 ◽

2016 ◽

Vol 2016 (1) ◽

pp. 612-619 ◽

Cited By ~ 16

Author(s):

Andrew W. Shih ◽

Mark A. Crowther

Keyword(s):

Phase 1 ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Antibody Fragment ◽

Factor Xa ◽

Factor Xa Inhibitors ◽

Severe Bleeding ◽

Thrombin Time ◽

Ancillary Benefits ◽

Reversal Agents

Abstract Direct oral anticoagulants (DOACs) have at least noninferior efficacy compared with other oral anticoagulants and have ancillary benefits, including overall better safety profiles, lack of the need for routine monitoring, rapid onset of action, and ease of administration. Reversal of these agents may be indicated in certain situations such as severe bleeding and for perioperative management. DOAC-associated bleeding should be risk stratified: patients with moderate or severe bleeding should have the DOAC discontinued and reversal strategies should be considered. Laboratory testing has limited utility in the acute management of bleeding; thrombin time and activated partial thromboplastin time may be useful for excluding clinically relevant levels of dabigatran. Prothrombin time is potentially useful for rivaroxaban and edoxaban, but calibrated anti-Xa assays are optimal for determining clinically relevant levels of factor Xa inhibitors. Because specific reversal agents are not widely available, supportive care and interventions for local hemostasis remain the cornerstones of therapy in the patient with DOAC-associated bleeding. Nonspecific reversal agents should be considered only in the event of severe bleeding because their efficacy is unknown, and they are associated with risk of thrombosis. Recent results from phase 3/4 studies demonstrate efficacy for an antidote to dabigatran (idarucizumab, a monoclonal antibody fragment with specificity for dabigatran) and an antidote to factor Xa inhibitors (andexanet alfa, a recombinant and inactive form of factor Xa that binds inhibitors). A universal reversal agent (ciraparantag) for many anticoagulants, including the DOACs, shows promise in results from phase 1 and 2 studies.

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