Today the coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a global health problem. After more than a year with the pandemic, ...although our knowledge has progressed on COVID-19, there are still many unknowns in virological, pathophysiological and immunological aspects. It is obvious that the most efficient solution to end this pandemic are safe and efficient vaccines. This manuscript summarizes the pathophysiological and thrombotic features of COVID-19 and the safety and efficacy of currently approved COVID-19 vaccines with an aim to clarify the recent concerns of thromboembolic events after COVID-19 vaccination. The influx of newer information is rapid, requiring periodic updates and objective assessment of the data on the pathogenesis of COVID-19 variants and the safety and efficacy of currently available vaccines.
Recombinant coagulation factor Xa (FXa), inactivated Zh-zo, also known as andexanet alfa (AA), is a modified version of human FXa that has been developed to neutralize FXa inhibitors. We studied the ...reversal effect of AA for these inhibitors in various anticoagulant and thrombin generation (TG) assays. Individual aliquots of normal human plasma containing 1 µg/mL of apixaban, betrixaban, edoxaban, and rivaroxaban, were supplemented with saline or AA at a concentration of 100 µg/mL. Clotting profiles include prothrombinase-induced clotting time, activated partial thromboplastin time, and prothrombin time. Factor Xa activity was measured using an amidolytic method. Thrombin generation was measured using a calibrated automated thrombogram. Differential neutralization of all 4 anticoagulants was noted in the activated clotting time and other clotting tests. The FXa activity reversal profile varied with an observed decrease in apixaban (22%), betrixaban (56%), edoxaban (28%), and rivaroxaban (49%). Andexanet alfa also led to an increased TG in comparison to saline. The peak thrombin was higher (40%), area under the curve (AUC) increased (15%), whereas the lag time (LT) decreased (17%). Andexanet alfa added at 100 µg/mL to various FXa supplemented systems resulted in reversal of the inhibitory effects, restoring the TG profile; AUC, LT, and peak thrombin levels were comparable to those of unsupplemented samples. Andexanet alfa is capable of reversing anti-Xa activity of different oral FXa inhibitors but overshoots thrombogenesis in both the saline and FXa inhibitor supplemented systems. The degree of neutralization of Xa inhibitor is specific to each agent.
Venous thromboembolism (VTE) is a prevalent, potentially fatal health problem. Although standard anticoagulant therapy is effective when compared with the newer direct oral anticoagulants (DOACs), it ...has disadvantages. Heparin and its derivatives must be administered parenterally, whereas use of oral vitamin K antagonists is complicated by unpredictable pharmacokinetics and pharmacodynamics, drug-food and drug-drug interactions and the requirement for frequent laboratory monitoring. Randomized phase 3 trials have demonstrated that patients receive similarly effective anticoagulation with the DOACs dabigatran, edoxaban, rivaroxaban and apixaban when compared with warfarin, with similar or reduced risk of bleeding. Extended therapy trials have consistently demonstrated superior effectiveness for DOAC treatment when compared with placebo in preventing VTE recurrence. This article presents a comprehensive review of the pharmacokinetics, pharmacodynamics and accumulated clinical trial evidence for each DOAC for short-term, long-term and extended VTE therapy, and it considers the potential implications these agents have for the clinical management of VTE.
Data on drug–drug interactions (DDI) of antineoplastic drugs with anticoagulants is scarce. We aim to evaluate factors associated with DDI of antineoplastic and supportive care drugs with ...anticoagulants resulting in modification of pharmacokinetics of these last mentioned. A literature review on DDI databases and summaries of products characteristics (SmPC) was done. Drug–drug interactions of 257 antineoplastic and supportive care drugs with direct oral anticoagulants (DOACs), warfarin, enoxaparin, or fondaparinux were categorized as no clinically significant expected DDI, potentially weak DDI, potentially clinically significant DDI, and recommendation against coadministration. Logistic regression models were performed to analyze the association between the dependent variable potentially clinically significant interaction/recommendation against coadministration and the mechanisms of DDI. Of the 1799 associations, 84.4% were absence of DDI, 3.6% potentially weak DDI, 10.2% potentially clinically relevant DDI, and 2.0% recommendation against coadministration. Warfarin has higher DDI potential than other anticoagulants. Enoxaparin and fondaparinux have fewer DDI than others. There was no difference between DOACs. Drug–drug interactions with apixaban and rivaroxaban was independently associated with the absence of CYP3A4 competition, P-glycoprotein inhibition, CYP3A4 induction, and drug class of tyrosine kinase inhibitors. Drug–drug interactions with dabigatran and edoxaban was associated with inhibition of P-glycoprotein and tyrosine kinase inhibitors. Warfarin, induction of CYP3A4, and inhibition of CYP2C9. Enoxaparin and fondaparinux, only tyrosine kinase inhibitors. Direct oral anticoagulants did not differ regarding DDI with antineoplastic agents. Warfarin presented more DDI than other anticoagulants. P-glycoprotein inhibition and CYP3A4 induction were independently associated with DDI of antineoplastic agents with DOACs.
A variety of viral infections are associated with hypercoagulable states and may be linked to the development of deep venous thrombosis and pulmonary embolism. The Zika and Chikungunya viral ...infections spread through the South and Central American continents, moving to North America in 2016, with severe cases of polyarthralgia, fever, and Guillain-Barré syndrome leading eventually to death. A decreased trend for both infections was reported in the first quarter of 2017. In this article, we report the possible association of venous thromboembolic events associated with Zika infection. After 2 cases of deep venous thrombosis in patients with acute Zika infections, D-dimer levels were measured in 172 consecutive patients who presented to the emergency department of a university hospital in an endemic region of Brazil with either Zika or Chikungunya infections confirmed by polymerase chain reaction tests. D-dimer levels were increased in 19.4% of 31 patients with Zika and in 63.8% of 141 patients with Chikungunya infections. The mechanisms behind this association are yet to be elucidated as well as the potential for venous thromboembolism prevention strategies for in-hospital patients affected by Zika and Chikungunya infections.
Background
The COMPASS trial demonstrated that in patients with peripheral arterial disease, the combination of rivaroxaban and aspirin compared with aspirin reduces the risk of major adverse limb ...events, but it is not known whether this combination can also improve symptoms in patients with intermittent claudication. The primary objective of this study is to evaluate the effect of the combination on claudication distance.
Study design
Eighty-eight patients with intermittent claudication will be randomized to receive rivaroxaban 2.5 mg twice daily plus aspirin 100 mg once daily or aspirin 100 mg once daily for 24 weeks. The primary outcome is the change in claudication distance from the baseline to 24 weeks, measured by 6 min walking test and treadmill test. The primary safety outcome is the incidence of major bleeding and clinically relevant non-major bleeding according to the International Society on Thrombosis and Hemostasis criteria.
Summary
The COMPASS CLAUDICATION trial will provide high-quality evidence regarding the effect of the combination of rivaroxaban and aspirin on claudication distance in patients with peripheral arterial disease.
This practical guidance, endorsed by the Brazilian Society of Thrombosis and Hemostasis and The Brazilian Society of Angiology and Vascular Surgery, the International Union of Angiology and the ...European Venous Forum, aims to provide physicians with clear guidance, based on current best evidence-based data, on clinical strategies to manage antithrombotic strategies in patients with coronavirus disease 2019.
Andexanet alfa is a recombinant factor Xa decoy protein, designed to reverse bleeding associated with oral anti-Xa agents. Andexanet alfa is also reported to neutralize the effects of heparin-related ...drugs. This study focused on the neutralization profiles of unfractionated heparin (UFH), enoxaparin, and, a chemically synthetic pentasaccharide, fondaparinux by andexanet alfa. Whole blood clotting studies were carried out using thromboelastography (TEG) and activated clotting time (ACT). The anticoagulant profile of UFH, enoxaparin, and fondaparinux was studied using the activated partial thromboplastin time (aPTT), thrombin time (TT), and amidolytic anti-Xa, and anti-IIa methods. Thrombin generation inhibition was studied using the calibrated automated thrombogram system. Reversal of each of these agents was studied by supplementing andexanet alfa at 100 µg/mL. In the TEG, andexanet alfa produced almost a complete reversal of the anticoagulant effects of UFH and enoxaparin; however, it augmented the effects of fondaparinux. In the ACT, aPTT, and TT, UFH produced strong anticoagulant effects that were almost completely neutralized by andexanet alfa. Enoxaparin produced milder anticoagulant responses that were partially neutralized, whereas fondaparinux did not produce any sizeable effects. In the anti-Xa and anti-IIa assays, UFH exhibited partial neutralization whereas enoxaparin and fondaparinux did not show any neutralization. All agents produced varying degrees of the inhibition of thrombin generation, which were differentially neutralized by andexanet alfa. These results indicate that andexanet alfa is capable of differentially neutralizing anticoagulant and antiprotease effects of UFH and enoxaparin in an assay-dependent manner. However, andexanet alfa is incapable of neutralizing the anti-Xa effects of fondaparinux.
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