scholarly journals Factors influencing vitamin K antagonists therapy / Factori care influențează terapia cu antagoniști ai vitaminei K

2015 ◽  
Vol 23 (2) ◽  
Author(s):  
Ioana Brudașcă
Keyword(s):  
Vitamin K ◽  
Genetic Factors ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Individual Variability ◽  
Response To Therapy ◽  
Anticoagulant Effect ◽  
Individual Response ◽  
Dose Requirement ◽  
Factors Influencing

AbstractVitamin K antagonists (VKAs) are widely used for the primary and secondary prevention of thromboembolism, their anticoagulant effect being monitored through INR. Achieving and maintaining a stable anticoagulation status is challenging, because of the narrow therapeutic range, and of the extremely variable individual response to therapy.Environmental factors such as age, gender, body mass, diet, herbal supplements, drugs, pre-existing pathology, as well as genetic factors can substantially influence the anticoagulant effect of VKAs. The main genetic factors that contribute to individual variability in response to VKAs are genetic polymorphisms in genes influencing VKAs’ metabolism (CYP2C9) and pharmacodynamic response (VKOR1) and account for about one third in the variation of warfarin and analogues dose requirement. Systematic genotyping of patients requiring warfarin therapy is still a matter of debate.Although novel oral anticoagulants (direct thrombin and factor Xa inhibitors) seem promising, VKAs are still frequently prescribed, therefore physicians should be aware of the various factors influencing VKAs’ effect, and educational programmes for doctors and patients should be conducted in that respect

scholarly journals Monitoring the Effects and Antidotes of the Non-vitamin K Oral Anticoagulants

2015 ◽  
Vol 04 (2) ◽  
pp. 90 ◽  
Author(s):  
Nur A Rahmat ◽  
Gregory Y H Lip ◽  
◽  
◽  
Keyword(s):  
Vitamin K ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Anticoagulant Effect

In the last decade, we have witnessed the emergence of the oral non-vitamin K oral anticoagulants (NOACs), which have numerous advantages compared with the vitamin K antagonists, particularly their lack of need for monitoring; as a result their use is increasing. Nonetheless, the NOACs face two major challenges: the need for reliable laboratory assays to assess their anticoagulation effect, and the lack of approved antidotes to reverse their action. This article provides an overview of monitoring the anticoagulant effect of NOACs and their potential specific antidotes in development.

scholarly journals Vitamin K antagonists in children with heart disease: height and VKORC1 genotype are the main determinants of the warfarin dose requirement

Blood ◽  
2012 ◽  
Vol 119 (3) ◽  
pp. 861-867 ◽  
Author(s):  
Caroline Moreau ◽  
Fanny Bajolle ◽  
Virginie Siguret ◽  
Dominique Lasne ◽  
Jean-Louis Golmard ◽  
...  
Keyword(s):  
Vitamin K ◽  
Dose Response ◽  
Maintenance Dose ◽  
Vitamin K Antagonists ◽  
Warfarin Dose ◽  
International Normalized Ratio ◽  
Individual Variability ◽  
Dose Requirement ◽  
Warfarin Dose Requirement ◽  
Main Determinants

Abstract Managing vitamin K antagonist (VKA) therapy is challenging in children because of a narrow therapeutic range and wide inter- and intra-individual variability in dose response. Only a few small studies have investigated the effect of nongenetic and genetic factors on the dose response to VKAs in children. In a cohort study including 118 children (median age 9 years; range, 3 months-18 years) mostly with cardiac disease, we evaluated by multivariate analysis the relative contribution of nongenetic factors and VKORC1/CYP2C9/CYP4F2 genotypes on warfarin (n = 83) or fluindione (n = 35) maintenance dose and the influence of these factors on the time spent within/above/below the range. The results showed that height, target international normalized ratio and VKORC1 and CYP2C9 genotypes were the main determinants of warfarin dose requirement, accounting for 48.1%, 4.4%, 18.2%, and 2.0% of variability, respectively, and explaining 69.7% of the variability. Our model predicted the warfarin dose within 7 mg/wk in 86.7% of patients. None of the covariates was associated with the time spent above or below the international normalized ratio range. Whether this model predicts accurately the effective maintenance dose is currently being investigated.

scholarly journals Gut Microbiota and the Quality of Oral Anticoagulation in Vitamin K Antagonists Users: A Review of Potential Implications

2021 ◽  
Vol 10 (4) ◽  
pp. 715
Author(s):  
Anny Camelo-Castillo ◽  
José Miguel Rivera-Caravaca ◽  
Esteban Orenes-Piñero ◽  
Inmaculada Ramírez-Macías ◽  
Vanessa Roldán ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Vitamin K ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Individual Variability ◽  
Future Research ◽  
The Mean ◽  
Anticoagulation Control ◽  
Mean Time

The efficacy and safety of vitamin K antagonists (VKAs) as oral anticoagulants (OACs) depend on the quality of anticoagulation control, as reflected by the mean time in therapeutic range (TTR). Several factors may be involved in poor TTR such as comorbidities, high inter-individual variability, interacting drugs, and non-adherence. Recent studies suggest that gut microbiota (GM) plays an important role in the pathogenesis of cardiovascular diseases, but the effect of the GM on anticoagulation control with VKAs is unknown. In the present review article, we propose different mechanisms by which the GM could have an impact on the quality of anticoagulation control in patients taking VKA therapy. We suggest that the potential effects of GM may be mediated first, by an indirect effect of metabolites produced by GM in the availability of VKAs drugs; second, by an effect of vitamin K-producing bacteria; and finally, by the structural modification of the molecules of VKAs. Future research will help confirm these hypotheses and may suggest profiles of bacterial signatures or microbial metabolites, to be used as biomarkers to predict the quality of anticoagulation. This could lead to the design of intervention strategies modulating gut microbiota, for example, by using probiotics.

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.

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.

scholarly journals Anticoagulation in Atrial Fibrillation Cardioversion: What Is Crucial to Take into Account

2021 ◽  
Vol 10 (15) ◽  
pp. 3212
Author(s):  
Fabiana Lucà ◽  
Simona Giubilato ◽  
Stefania Angela Di Fusco ◽  
Laura Piccioni ◽  
Carmelo Massimiliano Rao ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Vitamin K ◽  
Thrombus Formation ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Anticoagulation Therapy ◽  
Significant Advance ◽  
Thromboembolic Events ◽  
Thromboembolic Risk ◽  
Pharmacological Cardioversion

The therapeutic dilemma between rhythm and rate control in the management of atrial fibrillation (AF) is still unresolved and electrical or pharmacological cardioversion (CV) frequently represents a useful strategy. The most recent guidelines recommend anticoagulation according to individual thromboembolic risk. Vitamin K antagonists (VKAs) have been routinely used to prevent thromboembolic events. Non-vitamin K antagonist oral anticoagulants (NOACs) represent a significant advance due to their more predictable therapeutic effect and more favorable hemorrhagic risk profile. In hemodynamically unstable patients, an emergency electrical cardioversion (ECV) must be performed. In this situation, intravenous heparin or low molecular weight heparin (LMWH) should be administered before CV. In patients with AF occurring within less than 48 h, synchronized direct ECV should be the elective procedure, as it restores sinus rhythm quicker and more successfully than pharmacological cardioversion (PCV) and is associated with shorter length of hospitalization. Patients with acute onset AF were traditionally considered at lower risk of thromboembolic events due to the shorter time for atrial thrombus formation. In patients with hemodynamic stability and AF for more than 48 h, an ECV should be planned after at least 3 weeks of anticoagulation therapy. Alternatively, transesophageal echocardiography (TEE) to rule out left atrial appendage thrombus (LAAT) should be performed, followed by ECV and anticoagulation for at least 4 weeks. Theoretically, the standardized use of TEE before CV allows a better stratification of thromboembolic risk, although data available to date are not univocal.

scholarly journals The Risk of Gastrointestinal Bleeding between Non-Vitamin K Antagonist Oral Anticoagulants and Vitamin K Antagonists in the Asian Atrial Fibrillation Patients: A Meta-Analysis

2020 ◽  
Vol 18 (1) ◽  
pp. 137
Author(s):  
Kuang-Tsu Yang ◽  
Wei-Chih Sun ◽  
Tzung-Jiun Tsai ◽  
Feng-Woei Tsay ◽  
Wen-Chi Chen ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Gastrointestinal Bleeding ◽  
Vitamin K ◽  
Meta Analysis ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Vitamin K Antagonist ◽  
Cochrane Library ◽  
Secondary Outcome ◽  
Optimal Dosage

Background: Non-vitamin K antagonist oral anticoagulants (NOACs) are more commonly used to prevent atrial fibrillation (AF) patients from thromboembolic events than vitamin K antagonists (VKAs). However, the gastrointestinal bleeding (GIB) risk in the Asian AF patients associated with NOACs in comparison with VKAs remained unaddressed. Materials and Methods: A systematic search of studies on NOACs and VKAs in the Asian AF patients was conducted in PubMed, Cochrane Library, and ClinicalTrials.gov. The primary outcome was the hazard ratio (HR) of any GIB associated with NOACs versus VKAs. The secondary outcome was the GIB risks in different kinds of NOACs compared with VKAs. Results: This meta-analysis included two randomized controlled trials (RCTs) and four retrospective studies, comprising at least 200,000 patients in total. A significantly lower HR of GIB risks was found in all kinds of NOACs than VKAs in the Asian AF patients (HR: 0.633; 95% confidence interval: 0.535–0.748; p < 0.001). Additionally, the GIB risks of different NOACs were apixaban (HR: 0.392), edoxaban (HR: 0.603), dabigatran (HR: 0.685), and rivaroxaban (HR: 0.794), respectively. Conclusions: NOACs significantly reduced the risk of GIB in the Asian AF patients compared with VKAs. In the four NOACs compared with VKAs, apixaban probably had a trend of the least GIB risk. We need further head-to-head studies of different NOACs to confirm which NOAC is the most suitable for Asian AF patients and to know the optimal dosage regimen of different NOACs.

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