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Anticoagulation
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
Louis M. Fink, Nicole A. Massoll, Alex A. Pappas
Revasc (Revasc Norartis, Basal, Switzerland) has been compared with both UFH and LMWH in the prophylaxis of DVT after total hip replacement. In these studies, 15 mg b.i.d. of Revasc provided better outcome than heparin or enoxaparin. Thrombin inhibitors and hirudin have an extremely short T1/2 of about 30–40 min. Molecular engineering of prothrombin molecules has resulted in variants that can complex with hirudin to neutralize its anticoagulant effects. All of the antithrombin agents produce anticoagulant effect in such global tests as PT and aPTT. The mechanism of action of each of these agents is different; therefore differences in their prolongation of the clot-based assays may not be an indication of their anticoagulant/autothrombotic potency. A new clot-based assay known as the ecarin clotting time has been developed recently for the specific monitoring of antithrombin agents. Ecarin represents snake venom that converts prothrombin to meizothrombin, eventually producing a clotting end point. Each thrombin in-hibitor has its own distinct anticoagulant effect in this assay. In addition, ELISA-based assays have also been developed for absolute drug concentrations (74).
Clinical Toxicology of Snakebite In Africa and The Middle East / Arabian Peninsula
Published in Jürg Meier, Julian White, Handbook of: Clinical Toxicology of Animal Venoms and Poisons, 2017
Fibrinogen clotting activity has been found in the venoms of the gaboon viper (B. gabonica) ("Gabonase"), which splits off fibrinopeptides A and B from fibrinogen and also activates Factor XIII, and Cerastes vipera ("Cerastobin"). Ecarin, a metalloproteinase from the venom of “Echis carinatus”, activates prothrombin. Venoms of “E. carinatus”, E. coloratus and Cerastes cerastes activate Factor X. Procoagulant activity has also been demonstrated in the venoms of C. rhombeatus, Pseudocerastes persicus and Vipera lebetina.
Haemostasis and fibrinolysis
Published in Ken Myers, Paul Hannah, Marcus Cremonese, Lourens Bester, Phil Bekhor, Attilio Cavezzi, Marianne de Maeseneer, Greg Goodman, David Jenkins, Herman Lee, Adrian Lim, David Mitchell, Nick Morrison, Andrew Nicolaides, Hugo Partsch, Tony Penington, Neil Piller, Stefania Roberts, Greg Seeley, Paul Thibault, Steve Yelland, Manual of Venous and Lymphatic Diseases, 2017
Ken Myers, Paul Hannah, Marcus Cremonese, Lourens Bester, Phil Bekhor, Attilio Cavezzi, Marianne de Maeseneer, Greg Goodman, David Jenkins, Herman Lee, Adrian Lim, David Mitchell, Nick Morrison, Andrew Nicolaides, Hugo Partsch, Tony Penington, Neil Piller, Stefania Roberts, Greg Seeley, Paul Thibault, Steve Yelland
The ecarin clotting time can be used to monitor treatment with direct thrombin inhibitors (e.g. argatroban, dabigatran). Ecarin activates prothrombin to intermediate meizothrombin which forms complexes with direct thrombin inhibitors.
Direct oral anticoagulants in the treatment of pulmonary embolism
Published in Current Medical Research and Opinion, 2018
Joanna B. Eldredge, Alex C. Spyropoulos
Routinely available clot-based assays, such as prothrombin time and activated partial thromboplastin time assays, lack sensitivity and do not accurately quantify the anticoagulant effects of DOACs59. More accurate tests do exist, and these include the diluted thrombin time (Hemoclot assay), ecarin clot time, ecarin chromogenic assay, and anti-factor IIa chromogenic assay for dabigatran, and potentially the anti-factor Xa chromogenic assays for rivaroxaban, apixaban, and edoxaban. Although the Hemoclot assay reliably predicts clinically meaningful dabigatran concentrations, it is not available in many medical centers. In addition, the other assays lack standardization and are also not routinely available in clinical practice59. While routine monitoring of the anticoagulant effects of DOACs is not necessary, there is a potential need for rapidly available standardized assays for efficiently measuring the anticoagulant effects of DOACs during reversal of anticoagulation, as well as in certain clinical situations, such as life-threatening bleeding, emergent or urgent surgeries or procedures, and suspected overdose60. Costs associated with anticoagulation reversal agents are high, therefore, rapid access to standardized assays for efficiently measuring the anticoagulant effects of DOACs is needed to ensure that the reversal agents are used properly61.
The anticoagulant effect of therapeutic levels of dabigatran in atrial fibrillation evaluated by thrombelastography (TEG®), Hemoclot Thrombin Inhibitor (HTI) assay and Ecarin Clotting Time (ECT)
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2018
Sacha Solbeck, Annette Schophuus Jensen, Christian Maschmann, Jakob Stensballe, Sisse Rye Ostrowski, Pär I. Johansson
Ecarin is snake venom that activates prothrombin resulting in this being cleaved into an intermediate, meizothrombin, the precursor of thrombin. The ECT assay detects the dose-dependent inhibition of the thrombin-like activity of meizothrombin caused by direct thrombin inhibitors [16,23]. Results are also reported in seconds and translated to a concentration of dabigatran in ng/mL by linear regression [16]. The highest possible value for ECT is 1020 ng/mL.