scholarly journals Comparative Biology of the Resistance to Vitamin K Antagonists: An Overview of the Resistance Mechanisms

10.5772/64204 ◽  
2016 ◽  
Author(s):  
Sébastien Lefebvre ◽  
Etienne Benoit ◽  
Virginie Lattard
Keyword(s):  
Vitamin K ◽  
Vitamin K Antagonists ◽  
Resistance Mechanisms ◽  
Comparative Biology

Idiopathic venous thrombosis

2006 ◽  
Vol 26 (01) ◽  
pp. 52-54 ◽  
Author(s):  
P. A. Kyrle
Keyword(s):  
Chronic Disease ◽  
Venous Thrombosis ◽  
Vitamin K ◽  
Clinical Benefit ◽  
Plasma Levels ◽  
Vitamin K Antagonists ◽  
Antithrombin Deficiency ◽  
Optimal Duration ◽  
Risk Of Treatment

SummaryVenous thrombosis is a chronic disease with a recurrence rate of approximately 30% within 5-8 years. The optimal duration of secondary thromboprophylaxis in these patients entails balancing the risk of recurrence against the risk of treatment-associated bleeding. There is agreement that patients with a first idiopathic venous thrombosis should receive vitamin K antagonists for at least 3-6 months. Convincing trials showing a clinical benefit in terms of morbidity or mortality with respect to expansion of anticoagulation beyond 6 months are lacking. Nevertheless, some subgroups of patients with venous thrombosis may benefit from indefinite anticoagulation. Thus, patients with antithrombin deficiency, combined or homozygous defects, more than one unprovoked episode of thrombosis, the lupus anticoagulant or high factor VIII plasma levels are good candidates for long-term prevention.

Spectrophotometric Assays of Prothrombin in Plasma of Patients Using Oral Anticoagulants

1979 ◽  
Vol 42 (04) ◽  
pp. 1296-1305 ◽  
Author(s):  
R M Bertina ◽  
W van der Marel-van Nieuwkoop ◽  
E A Loeliger
Keyword(s):  
Prothrombin Time ◽  
Vitamin K ◽  
Oral Anticoagulation ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Factor Xa ◽  
Factor V ◽  
Anticoagulant Treatment ◽  
Factor Ii ◽  
K Deficiency

SummaryTwo spectrophotometric assays for prothrombin have been developed and compared with a one stage coagulant and an immunological assay. One of these assays (called the XAPC assay) uses a combination of factor Xa, phospholipid, Ca2+ and factor V as activator of prothrombin, and measures only normal prothrombin. The second (the ECAR assay) uses Echis carinatus venom as activator. This assay measures both normal prothrombin and PIVKA II (protein induced by vitamin K antagonists/absence). Combination of the results obtained by the XAPC and ECAR assays provides rapid and reliable information on the degree of “subcarboxylation” of prothrombin (oral anticoagulation, vitamin K deficiency).For patients on long term anticoagulant treatment the prothrombin time (Thrombotest) shows better correlation with the ratio prothrombin/prothrombin plus PIVKA II (XAPC/ ECAR) than with the factor II concentration. For patients starting the anticoagulant treatment there is no correlation between the Thrombotest time and the XAPC/ECAR ratio.It seems doubtful that (a) spectrophotometric factor II assay(s) will be as useful as the prothrombin time in the control of oral anticoagulation.

New Drugs for Thromboembolic Prevention in Atrial Fibrillation

2010 ◽  
Vol 6 (4) ◽  
pp. 64
Author(s):  
Jose L Merino ◽  
Jose López-Sendón ◽  
◽  
Keyword(s):  
Atrial Fibrillation ◽  
Vitamin K ◽  
Negative Impact ◽  
Vitamin K Antagonists ◽  
Coagulation Factor ◽  
Developed Countries ◽  
New Drugs ◽  
Risk Scores ◽  
Bleeding Events ◽  
Risk Patients

Atrial fibrillation (AF) is the most frequent sustained arrhythmia and its prevalence is increasing in developed countries. This progressive increase and the negative impact of this arrhythmia on the patient’s prognosis make AF one of the main healthcare problems faced today. This has led to intense research into the main aspects of AF, one of them being thromboembolism prevention. AF patients have a four to five times higher risk of stroke than the general population. Several factors increase thromboembolic risk in patients with AF and the use of risk scores, such as the Congestive Heart Failure, Hypertension, Age Greater than 75, Diabetes, and Prior Stroke or Transient Ischemic Attack (CHADS2), have been used to identify the best candidates for anticoagulation. Antithrombotic drugs are the mainstay of therapy for embolic prevention. The clinical use of these drugs is based on the risk–benefit ratio, where benefit is the reduction of stroke and systemic embolic events and risk is mostly driven by the increase in bleeding events. Generally, antiplatelets are indicated for low-risk patients in light of the fact anticoagulants are the drug of choice for moderate- or high-risk patients. Vitamin K antagonists have been the only option for oral anticoagulation for the last 50 years. However, these drugs have many pharmacodynamic and pharmacokinetic problems. The problems of anticoagulation with vitamin K antagonists have led to the investigation of new drugs that can be administered orally and have a better dose–response relationship, a shorter half-life and, in particular, higher efficacy and safety without the need for frequent anticoagulation controls. The drugs that have been studied most thoroughly in patients with AF are inhibitors of the activated coagulation factor X and inhibitors of coagulation factor II (thrombin), including ximelagatran and dabigatran. In addition, non-pharmacological therapies have been developed to prevent recurrent embolism in certain patient populations.

Perioperative Management of Patients Receiving New Anticoagulants

2019 ◽  
Vol 25 (19) ◽  
pp. 2149-2157 ◽  
Author(s):  
Massimo Lamperti ◽  
Andrey Khozenko ◽  
Arun Kumar
Keyword(s):  
Vitamin K ◽  
Elective Surgery ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Oral Intake ◽  
Bleeding Risk ◽  
Dietary Vitamin ◽  
Reversal Agent ◽  
Onset Of Action ◽  
Reversal Agents

There is an increased use of oral anticoagulants for the prevention of venous and arterial thrombosis. Vitamin-K antagonists have been used for decades as the main oral anticoagulants but they have the draback a complex therapeutic management, slow onset of action and by a different oral intake caused by dietary vitamin K intake. New non-vitamin K antagonist oral anticoagulants (NOACs) have been developed to overcome the limitations of warfarin. Their management is easier as it requires a fixed daily dose without coagulation monitoring. Although their therapeutic profile is safe, proper attention should be paid in case of unexpected need for the reversal of their coagulation effect and in case a patient needs to have a scheduled surgery. For non-acute cardiac surgery, discontinuation of NOACs should start at least 48 hours prior surgery. Intracranial bleedings associated with NOACs are less dangerous comparing to those warfarin-induced. NOACs need to be stopped ≥24 hours in case of elective surgery for low bleeding-risk procedures and ≥48 hours for high bleeding-risk surgery in patients with normal renal function and 72 hours in case of reduced CrCl < 80. The therapy with NOACs should be resumed from 48 to 72 hours after the procedure depending on the perceived bleeding, type of surgery and thrombotic risks. There are some available NOAC reversal agents acting within 5 to 20 minutes. In case of lack of reversal agent, adequate diuresis, renal replacement therapy and activated charcoal in case of recent ingestion should be considered.

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