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Academic literature on the topic 'Warfarin dosage'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Warfarin dosage"

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Lala, Mallika, Gilbert J. Burckart, Cheryl M. Takao, Vera Pravica, Jeremiah D. Momper, and Jogarao V. S. Gobburu. "Genetics-Based Pediatric Warfarin Dosage Regimen Derived Using Pharmacometric Bridging." Journal of Pediatric Pharmacology and Therapeutics 18, no. 3 (September 1, 2013): 209–19. http://dx.doi.org/10.5863/1551-6776-18.3.209.

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BACKGROUND Warfarin dosage regimens using CYP2C9 and VKORC1 polymorphisms have been extensively studied in adults and is included in US Food and Drug Administration-approved warfarin labeling. However, no dosage algorithm is available for pediatric patients. OBJECTIVE To derive a genetics-based pediatric dosge regimen for warfarin, including starting dose and titration scheme. METHODS A model-based approach was developed based on a previously validated warfarin dosage model in adults, with subsequent comparison to pediatric data from pediatric warfarin dose, genotyping, and international normalized ratio (INR) results. The adult model was based on a previously established model from the CROWN (CReating an Optimal Warfarin dosing Nomogram) trial. Pediatric warfarin data were obtained from a study conducted at the Children’s Hospital of Los Angeles with 26 subjects. Variant alleles of CYP2C9 (rs1799853 or *2, and rs1057910 or *3) and the VKORC1 single nucleotide polymorphism (SNP) rs9923231 (−1639 G>A) were assessed, where the rs numbers are reference SNP identification tags assigned by the National Center for Biotechnology Information. RESULTS A pediatric warfarin model was derived using the previously validated model and clinical pharmacology considerations. The model was validated, and clinical trial simulation and stochastic modeling were used to optimize pediatric dosage and titration. The final dosage regimen was optimized based on simulations targeting a high (≥60%) proportion of INRs within the therapeutic range by week 2 of warfarin therapy while minimizing INRs >3.5 or <2. CONCLUSIONS The proposed pediatric warfarin dosage scheme based on individual CYP2C9 (alleles *1,*2,*3) and VKORC1 rs9923231 (-1639 G>A) genotypes may offer improved dosage compared to current treatment strategies, especially in patients with variant CYP2C9 and VKORC1 alleles. This pilot study provides the foundation for a larger prospective evaluation of genetics-based warfarin dosage in pediatric patients.
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Recker, Mark W., and Karen L. Kier. "Potential Interaction between Clarithromycin and Warfarin." Annals of Pharmacotherapy 31, no. 9 (September 1997): 996–98. http://dx.doi.org/10.1177/106002809703100907.

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Objective To report a possible drug interaction between clarithromycin and warfarin in a patient with chronic atrial fibrillation. Case Summary A patient with chronic atrial fibrillation was placed on warfarin therapy. International normalized ratios (INRs) ranged from 1.61 to 3.99 while the dosage was being adjusted during the first 5 months of warfarin therapy. The dosage was titrated to 20 mg/wk; laboratory tests obtained 2 weeks after this dosage was started indicated an INR of 2.1. The same dosage was continued. Clarithromycin 500 mg bid was started for an acute exacerbation of bronchitis 10 days after the last INR was obtained and was continued for 14 days of therapy. An INR obtained 3 days after completion of the clarithromycin therapy was 16.8. The warfarin was withheld and vitamin K 20 mg im was administered. The INR obtained the next day was 1.52. The warfarin was restarted and the dosage was titrated to between 22.5 and 25 mg/wk, with INRs ranging from 0.85 to 3.14. Discussion Many factors influence the metabolism of warfarin, including disease states, medications, age, and diet. Data collected in this case suggested clarithromycin may have contributed to the increase in the effect of warfarin. Inhibition of the cytochrome P450 oxidizing system appears to be the reason for the increase. Numerous drugs and disease states affect the rate at which this system metabolizes drugs. Conclusions The potential interaction between clarithromycin and warfarin warrants prudent monitoring of the INR during concurrent administration of these drugs. Warfarin dosages may need to be reduced during concurrent clarithromycin therapy to prevent bleeding complications. Further controlled clinical trials are needed to substantiate the interaction between clarithromycin and warfarin.
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Zatuchni, Jacob. "Guidelines for Warfarin Dosage." Drug Intelligence & Clinical Pharmacy 22, no. 10 (October 1988): 825–26. http://dx.doi.org/10.1177/106002808802201022.

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Liu, Hong-Qiang, Chang-Po Zhang, Chang-Zhen Zhang, Xiang-Chen Liu, and Zun-Jing Liu. "Influence of Two Common Polymorphisms in theEPHX1Gene on Warfarin Maintenance Dosage: A Meta-Analysis." BioMed Research International 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/564149.

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We conducted a meta-analysis to investigate the influence of two common single nucleotide polymorphisms (SNPs) (rs2292566 G>A and rs4653436 A>G) in theEPHX1gene on warfarin maintenance dosages. Relevant literatures were searched using thePubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, CBM, andCNKIdatabases without any language restrictions. STATA Version 12.0 software (Stata Corporation, College Station, TX, USA) was used for this meta-analysis. Standard mean difference and its corresponding 95% confidence interval (95% CI) were calculated. Seven studies met the inclusion criteria, including 2,063 warfarin-treated patients. Meta-analysis results illustrated thatEPHX1rs2292566 G>A polymorphism might be strongly correlated with a higher maintenance dose of warfarin. However, no interaction ofEPHX1rs4653436 A>G polymorphism with warfarin maintenance dosage was detected. A further subgroup analysis based on stratification by ethnicity indicated thatEPHX1rs2292566 G>A polymorphism was positively correlated with warfarin maintenance dosage among Caucasians, but not Asians. No associations were observed betweenEPHX1rs4653436 A>G polymorphism warfarin maintenance dosage among both Caucasians and Asians. Our meta-analysis provides robust and unambiguous evidence thatEPHX1rs2292566 polymorphism may affect the maintenance dose of warfarin in Caucasians.
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Kim, Karissa Y., and Michael A. Mancano. "Fenofibrate Potentiates Warfarin Effects." Annals of Pharmacotherapy 37, no. 2 (February 2003): 212–15. http://dx.doi.org/10.1177/106002800303700210.

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OBJECTIVE: To describe 2 patients in whom the initiation of fenofibrate potentiated warfarin's anticoagulant effects. CASE SUMMARY: A 71-year-old white woman and an 80-year-old white woman with multiple medical conditions were both stabilized on long-term warfarin therapy. During the course of anticoagulation, both patients were prescribed fenofibrate and experienced threefold and twofold increases in international normalized ratio (INR), respectively, requiring total weekly warfarin dosage reductions of 30–40%. Before starting fenofibrate therapy, both patients' coagulation values were within the therapeutic range. When interviewed, patients and caregivers denied bleeding, bruising, changes in diet, alcohol ingestion, nonadherence with therapy, or changes in drug regimen except for the addition of fenofibrate. Upon chart review, evaluation of potentially contributory parameters, such as other changes in drug therapy, thyroid function, liver function, and drug–disease interactions, showed that these parameters remained stable and were ruled noncontributory. DISCUSSION: The addition of fenofibrate in 2 patients on stable and therapeutic doses of warfarin increased the anticoagulant response to warfarin. A clear temporal relationship with the addition of fenofibrate and the appearance of the interaction was seen. Fenofibrate is highly protein bound, with the potential to displace warfarin from its binding protein, leading to an enhanced hypoprothrombinemic effect. Fenofibrate is also a mild to moderate inhibitor of CYP2C9, the enzyme responsible for warfarin metabolism. The combination of these effects — displacement of warfarin by fenofibrate coupled with decreased metabolism of warfarin — may increase the anticoagulant response to warfarin. Using the Naranjo probability scale, these interactions were designated as probable. CONCLUSIONS: We suggest serial monitoring of INR and consider an empiric 20% reduction in warfarin dosage when fenofibrate is initiated, with the possibility for a greater warfarin dosage reduction based on INR results.
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Dang, Mai-Trang N., Julie Hambleton, and Steven R. Kayser. "The Influence of Ethnicity on Warfarin Dosage Requirement." Annals of Pharmacotherapy 39, no. 6 (June 2005): 1008–12. http://dx.doi.org/10.1345/aph.1e566.

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BACKGROUND: The optimal dose of warfarin varies among individuals, and the prediction of a maintenance dose is difficult. Ethnicity has been reported to influence warfarin dosing. OBJECTIVE: To quantitate the influence of ethnicity on warfarin dose requirement. METHODS: We conducted a retrospective cohort study at a university anticoagulation clinic to evaluate the influence of ethnicity on warfarin dose. Inclusion criteria included age ⩾18 years, target international normalized ratio (INR) 2–3, and warfarin management within the clinic for ⩾3 months with a minimum of 5 clinic visits. We collected clinical and demographic data including age, gender, weight, ethnicity, disease states, concomitant medications, indication, weekly warfarin dosage, and INR. To assess potential confounders, multivariate, repeated-measures regression analysis was used to identify and adjust for variables that may influence the maintenance dose of warfarin. RESULTS: Of the 345 patients who met the inclusion criteria, 27% were Asian American, 6% Hispanic, 54% white, and 14% African American. The adjusted mean (95% CI) weekly warfarin doses for patients with an INR goal of 2 to 3 were Asian Americans 24 mg (21 to 27), Hispanics 31 mg (25 to 37), whites 36 mg (34 to 39), and African Americans 43 mg (39 to 47) (p < 0.001). Additional factors found to influence warfarin dose requirement included age, weight, concomitant use of amiodarone, and diagnosis of venous thromboembolism. CONCLUSIONS: Warfarin dose requirements vary across ethnic groups even when adjusted for confounding factors, suggesting that genetic variation contributes to interpatient variability.
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Müller, C. R., S. Rost, M. Watzka, C. G. Bevans, and J. Oldenburg. "Comparative genetics of warfarin resistance." Hämostaseologie 34, no. 02 (2014): 143–59. http://dx.doi.org/10.5482/hamo-13-09-0047.

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SummaryWarfarin and other 4-hydroxycoumarinbased oral anticoagulants targeting vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) are administered to humans, mice and rats with different purposes in mind – to act as pesticides in high-dosage baits for killing rodents, but also to save lives when administered in low dosages as antithrombotic drugs in humans. However, high-dosage warfarin used to control rodent populations has resulted in numerous mutations causing warfarin resistance. Currently, six single missense mutations in mice, 12 distinct missense mutations in rats, as well as compound heterozygous or homozygous mutations with up to six distinct missense mutations per Vkorc1 allele have been described. Warfarin resistance missense mutations for human VKORC1 have also been found world-wide, but differ characteristically from those in rodents. In humans, 26 distinct mutations have been characterized, but occur only rarely either in heterozygous or, even rarer, in homozygous form.In this review, we summarize the known VKORC1 missense mutations causing warfarin and other 4-hydroxycoumarin drug resistance, identify genomics databases as new sources of data, explore possible underlying genetic mechanisms, and summarize similarities and differences between warfarin resistant VKORC1 variants in humans and rodents.
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Absher, Randall K., M. Elisabeth Moore, and Mary H. Parker. "Patient-Specific Factors Predictive of Warfarin Dosage Requirements." Annals of Pharmacotherapy 36, no. 10 (October 2002): 1512–17. http://dx.doi.org/10.1345/aph.1c025.

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OBJECTIVE: To identify patient-specific factors predictive of maintenance warfarin dosage requirements >5 mg/d. METHODS: One hundred forty-six adults taking warfarin were identified from a community hospital and an outpatient anticoagulation clinic. Patient demographics and data on warfarin doses, laboratory results, and medication use were obtained by abstracting patient records. Estimates of vitamin K intake were obtained using a questionnaire and structured interview. Multiple logistic regression was used to identify patient characteristics independently predictive of warfarin maintenance requirements >5 mg/d. An assessment tool for estimating an individual patient's likelihood of requiring warfarin maintenance doses >5 mg/d was derived from the logistic regression model and was assessed in both the study cohort and a separate historical validation cohort of 125 patients. RESULTS: Five factors were independently associated with warfarin requirements >5 mg/d: age <55 years, male gender, African American ethnicity, vitamin K intake >400 μg/d, and body weight ≥91 kg. The assessment tool derived from these factors correctly classified semiquantitative warfarin requirements as non—high-dose in 84 of 93 study cohort patients and 71 of 78 validation cohort patients, and correctly classified requirements as high-dose in 10 of 13 study cohort patients and 11 of 15 validation cohort patients. CONCLUSIONS: African American ethnicity is a newly identified predictor of warfarin requirements >5 mg/d and is independent of dietary vitamin K intake. An assessment tool incorporating this and other predictors can estimate a patient's likelihood of requiring such dosages.
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Zhu, Yusheng, Michael Shennan, Kristen K. Reynolds, Nancy A. Johnson, Matthew R. Herrnberger, Roland Valdes, and Mark W. Linder. "Estimation of Warfarin Maintenance Dose Based on VKORC1 (−1639 G>A) and CYP2C9 Genotypes." Clinical Chemistry 53, no. 7 (July 1, 2007): 1199–205. http://dx.doi.org/10.1373/clinchem.2006.078139.

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Abstract Background: CYP2C9 polymorphisms are associated with decreased S-warfarin clearance and lower maintenance dosage. Decreased expression of VKORC1 resulting from the −1639G&gt;A substitution has also been implicated in lower warfarin dose requirements. We investigated the additional contribution of this polymorphism to the variance in warfarin dose. Methods: Sixty-five patients with stable anticoagulation were genotyped for CYP2C9 and VKORC1 with Tag-It™ allele-specific primer extension technology. Plasma S-warfarin concentrations and warfarin maintenance dose were compared among patients on the basis of the VKORC1 −1639G&gt;A genotype. Results: Eighty percent of CYP2C9*1/*1 patients stabilized on &lt;4.0 mg/day warfarin had at least 1 VKORC1 −1639A allele. Mean warfarin doses (SD) were 6.7 (3.3), 4.3 (2.2), and 2.7 (1.2) mg/day for patients with the VKORC1 −1639GG, GA, and AA genotypes, respectively. Steady-state plasma concentrations of S-warfarin were lowest in patients with the VKORC1 −1639AA genotype and demonstrated a positive association with the VKORC1 −1639G allele copy number (trend P = 0.012). A model including VKORC1 and CYP2C9 genotypes, age, sex, and body weight accounted for 61% of the variance in warfarin daily maintenance dose. Conclusions: The VKORC1 −1639A allele accounts for low dosage requirements of most patients without a CYP2C9 variant. Higher plasma S-warfarin concentrations corresponding to increased warfarin maintenance dosages support a hypothesis for increased expression of the VKORC1 −1639G allele. VKORC1 and CYP2C9 genotypes, age, sex, and body weight account for the majority of variance in warfarin dose among our study population.
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Edwards, Clive, Timothy Butler, Hilary Wynne, and Farhad Kamali. "The Influence of (R)- and (S)-Warfarin, Vitamin K and Vitamin K Epoxide upon Warfarin Anticoagulation." Thrombosis and Haemostasis 84, no. 07 (2000): 39–42. http://dx.doi.org/10.1055/s-0037-1613964.

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SummaryThe contribution of (R)and (S)-warfarin enantiomers, vitamin K and vitamin K epoxide and patient factors to inter-individual variability in daily warfarin requirements were examined in a group of 73 patients. Simple correlation analysis showed a significant positive relationship between INR values and plasma (S)-warfarin concentrations (r = 0.25; p = 0.038). Multivariate analysis for relationships with INR demonstrated a highly significant positive relationship between INR and (S)- warfarin (p = 0.004) and plasma vitamin K epoxide concentrations (p = 0.028), and a significant negative relationship between INR and plasma vitamin K concentrations (p = 0.034). Twenty five percent of variation in INR could be explained by these variables (adjusted R2 = 0.25). Correlation analysis of data showed that warfarin dosage was significantly and negatively correlated with patient age (r = −0.42; p <0.0001). Patient age accounted for 25% of variation in warfarin dosage requirements (R2 = 0.25). The combined effects of age and vitamin K appear to account for much of the inter-individual variability in warfarin dosage requirements.
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Dissertations / Theses on the topic "Warfarin dosage"

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Ibrahim, Saied. "Investigating methods of improving the safety of oral anticoagulation with computer assisted dosage and standardisation of the International Normalised Ratio." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/investigating-methods-of-improving-the-safety-of-oral-anticoagulation-with-computer-assisted-dosage-and-standardisation-of-the-international-normalised-ratio(a51f3881-e55b-4b99-abba-6d2c6cfe7564).html.

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This thesis combines five published research papers investigating methods of improving the safety and control of oral anticoagulation, with the use of computer assisted dosage and the standardisation of the International Normalised Ratio (INR). The INR is a conventional measurement derived from the time it takes blood of a patient to form a clot and is used to monitor the effects of widely used oral anticoagulants such as warfarin for the prevention of stroke and other related disorders. The first paper investigates whether the use of computer-assisted programs was as safe and effective as medical staff manual dosage in the prevention of bleeding or thrombotic complications during oral anticoagulant treatment. This was an international multi-centre randomised study conducted by the European Action on Anticoagulation (EAA) investigating the clinical benefit of two computer programs, PARMA 5 (Italy) and DAWN AC (UK). Composite clinical events were reduced by 7.6% using computer programs, though not achieving statistical significance (p=0.1), showing computer programs to be not dissimilar to medical staff dosage. The second paper recommends guidelines for screening safety and effectiveness of other marketed computer programs based on the results of the EAA study. A process for a candidate computer program to achieve non-inferiority relative to the medical staff dosage arm from the EAA study is explained. The third paper introduces a modified approach to the 'Direct INR' method for the standardisation of INR termed the 'Prothrombin Time/INR Line' (PT/INR). This was directly compared to the local International Sensitivity Index (ISI) calibration procedure originally approved by the World Health Organisation and later by the United States Food and Drug Administration (FDA). Using manually certified lyophilised plasmas tested by specialist centres, the PT/INR Line using a set of 5 calibrant plasmas to establish a fitted line to estimate local INR was shown to be as effective as the FDA procedure. The fourth paper investigates the PT/INR Line further by using simulated sets of calibrant plasmas across the therapeutic range of 2.0-4.5 INR and determining the PT/INR Line. Local INR of five validation plasmas, certified by 3 centres using the manual PT technique, was determined using the estimated PT/INR Lines and compared with local ISI calibration. Using 4 or 5 calibrant plasmas to determine the PT/INR Line was shown to be as accurate as local ISI calibrations for reliable local INR.The fifth and final paper assessed INR variability and control in oral anticoagulant therapy using a method termed the Variance Growth Rate (VGR), and compared its predictive ability of adverse events with the Time in Target INR range (TIR), the conventional method used in evaluating the quality of oral anticoagulant therapy. The VGR method was shown to be a better predictor of adverse bleeding or thrombotic episodes in the short term period prior to an event (3 and 6 months) compared with TIR.
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Eriksson, Niclas. "On the Prediction of Warfarin Dose." Doctoral thesis, Uppsala universitet, Klinisk farmakologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-172864.

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Warfarin is one of the most widely used anticoagulants in the world. Treatment is complicated by a large inter-individual variation in the dose needed to reach adequate levels of anticoagulation i.e. INR 2.0 – 3.0. The objective of this thesis was to evaluate which factors, mainly genetic but also non-genetic, that affect the response to warfarin in terms of required maintenance dose, efficacy and safety with special focus on warfarin dose prediction. Through candidate gene and genome-wide studies, we have shown that the genes CYP2C9 and VKORC1 are the major determinants of warfarin maintenance dose. By combining the SNPs CYP2C9 *2, CYP2C9 *3 and VKORC1 rs9923231 with the clinical factors age, height, weight, ethnicity, amiodarone and use of inducers (carbamazepine, phenytoin or rifampicin) into a prediction model (the IWPC model) we can explain 43 % to 51 % of the variation in warfarin maintenance dose. Patients requiring doses < 29 mg/week and doses ≥ 49 mg/week benefitted the most from pharmacogenetic dosing. Further, we have shown that the difference across ethnicities in percent variance explained by VKORC1 was largely accounted for by the allele frequency of rs9923231. Other novel genes affecting maintenance dose (NEDD4 and DDHD1), as well as the replicated CYP4F2 gene, have small effects on dose predictions and are not likely to be cost-effective, unless inexpensive genotyping is available. Three types of prediction models for warfarin dosing exist: maintenance dose models, loading dose models and dose revision models. The combination of these three models is currently being used in the warfarin treatment arm of the European Pharmacogenetics of Anticoagulant Therapy (EU-PACT) study. Other clinical trials aiming to prove the clinical validity and utility of pharmacogenetic dosing are also underway. The future of pharmacogenetic warfarin dosing relies on results from these ongoing studies, the availability of inexpensive genotyping and the cost-effectiveness of pharmacogenetic driven warfarin dosing compared with new oral anticoagulant drugs.
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King, Barry Philip. "Genetic factors affecting warfarin dose requirements and clearance." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417716.

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Hamberg, Anna-Karin. "Pharmacometric Models for Individualisation of Warfarin in Adults and Children." Doctoral thesis, Uppsala universitet, Klinisk farmakogenomik och osteoporos, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-197599.

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Warfarin is one of the most widely used anticoagulants. Therapy is complicated by warfarin’s narrow therapeutic range and pronounced variability in individual dose requirements. Although warfarin therapy is uncommon in children, it is crucial for children with certain congenital or acquired heart diseases. Treatment in children is especially difficult due to the lack of i) a decision support tool for efficient and consistent dose adjustments, and ii) a flexible warfarin formulation for accurate and reproducible dosing. The overall aim of this thesis was to develop a PKPD-based pharmacometric model for warfarin that describes the dose-response relationship over time, and to identify important predictors that influence individual dose requirements both in adults and children. Special emphasis was placed on investigating the contribution of genetic factors to the observed variability. A clinically useful pharmacometric model for warfarin has been developed using NONMEM. The model has been successfully reformulated into a KPD-model that describes the relationship between warfarin dose and INR response, and that is applicable to both adults and children. From a clinical perspective, this is a very important change since it allows the use of information on dose and INR that is available routinely. The model incorporates both patient and clinical characteristics, such as age, weight, CYP2C9 and VKORC1 genotype, and baseline and target INR, for the prediction of an individualised starting dose. It also enables the use of information from previous doses and INR observations to further individualise the dose a posteriori using a Bayesian forecasting method. The NONMEM model has been transferred to a user-friendly, platform independent tool to aid use in clinical practice. The tool can be used for a priori and a posteriori individualisation of warfarin therapy in both adults and children. The tool should ensure consistent dose adjustment practices, and provide more efficient individualisation of warfarin dosing in all patients, irrespective of age, body weight, CYP2C9 or VKORC1 genotype, baseline or target INR. The expected outcome is improved warfarin therapy compared with empirical dosing, with patients achieving a therapeutic and stable INR faster and avoiding high INRs that increase the risk of bleeding.
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Majeed, Habeeb. "Supplementation to Improve Anticoagulation Control with Low Dose Vitamin K as an Adjuvant to Warfarin Therapy: A Double-blind, Placebo-controlled Randomized Controlled Trial." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23237.

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Vitamin K Antagonists [VKA] are the most frequently used oral anticoagulants in clinical practice; however, many patients fail to achieve adequate anticoagulation control. We conducted a randomized, placebo controlled, double blind study of Vitamin K1 (200mcg per day, Swanson Vitamins) in a population with predominantly venous thromboembolism aimed at evaluating its effectiveness in improving anticoagulation control in unstable patients. This study also aimed to evaluate the impact that clinical variables, patient anticoagulation knowledge, and genetic polymorphisms in genes known to impact warfarin and Vitamin K metabolism [VKORC1, CYP4F2, CYP2C9] had on anticoagulation control and intervention effectiveness. A total of N=54 patients were enrolled in the study over 15 months [January 2009 to June 2010]. Change score analysis and multivariate linear regression modelling of anticoagulation control measures were performed. No statistically significant reduction was observed in the Vitamin K1 arm for percent time in therapeutic range; however, reduction was observed in standard deviation of INRs [Change Score Vitamin K = -0.259, p=0.0261; Regression Model 95% C.I Beta Vitamin K = 0.38 to -0.08] during the intervention period. Adjusting for treatment group allocation, independent predictors of increased INR standard deviation included: >5 alcoholic drinks per week [95% C.I Beta = 0.04 to 0.41], self-reported dosing errors [95% C.I Beta = 0.13 to 0.47], and missed INR appointments [95% C.I Beta = 0.002 to 0.05]
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Makambwa, Edson. "The role of warfarin pharmacogenomics on the time it takes to reach stable therapeutic International Normalized Ratio (INR) and on warfarin dose required to maintain stable therapeutic INR in Black African and Mixed Ancestry South Africans: a focus on CYP2C9 and VKORC1." Master's thesis, Faculty of Health Sciences, 2019. http://hdl.handle.net/11427/31178.

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Warfarin, the most commonly prescribed anticoagulant, is principally metabolized by cytochrome P450 2C9 which functions by inhibiting the Vitamin K epoxide reductase. Genes CYP2C9 and VKORC1 code for these two proteins, respectively. CYP2C9 and VKORC1 exhibit genetic polymorphisms that have been shown to affect warfarin response and favorably facilitate warfarin dosing and improve clinical outcomes. However, none of these studies have involved populations from sub-Saharan Africa where the potential benefit of optimal dosing and reduced complications is greatest. Therefore, the thesis describes a study designed to investigate the role of genetic variations in CYP2C9 and VKORC1 on the time taken to reach a stable therapeutic international normalized ratio (INR) and warfarin dose required to maintain a therapeutic INR. This was a cross-sectional study of patients on warfarin to determine the relationship between genetic polymorphism in CYP2C9 and VKORC1 amongst black and mixed ancestry South Africans and clinical surrogates of warfarin metabolism. Medical records were accessed to determine time to INR and warfarin doses. DNA was extracted from blood samples, and genotyping for polymorphism in CYP2C9 (*2,*3,*8,*11) and VKORC1 (1173C>T, 1639G>A, 3730G>A) was accomplished by PCR-RFLP, Sanger sequencing and iPlex Mass Sequencing. Our results show that the genetic profile of CYP2C9 and VKORC1 differs between Black Africans (BA) and their Mixed Ancestry (MA) counterparts. VKORC1-1639AA genotype was observed at frequencies of 0.11 and 0.01 in the MA and BA, respectively. Time to stable INR was not influenced by CYP2C9 and VKORC1. Furthermore, compared to known genetic polymorphisms in these genes from population out of Africa, both qualitative and quantitative differences were observed. Finally, we found that VKORC1 genetic variation significantly affected the doses of warfarin in MA but had no effect in BA. These results suggest that further research in this area is warranted, and that it will be important to include populations from sub-Saharan Africa in future if the potential to develop personalized algorithms which integrate pharmacogenomics to assist with effective warfarin dosing and prevention of warfarin related complications is to be realized.
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Tai, Chuntien, and 戴俊典. "A Research of Data Mining in Warfarin Dosage Decisions." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/12554411984456215497.

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碩士
國立中正大學
資訊管理學系暨研究所
99
Drug safety has become one of the most critical indicators in patient safety. In recent years, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has paid considerable attention to the safety of anticoagulant administration. Among all anticoagulants, Warfarin has long been listed among the top ten drugs causing adverse drug events (ADE). This paper investigates a number of supervised learning techniques, including artificial neural network (ANN), model tree (M5), support vector machines (SVM), and k-nearest neighbors (kNN), to construct a Warfarin dosage prediction model. To achieve higher prediction accuracy, we further consider both Bagging algorithms and ensemble classifiers in experimental evaluation. For performance evaluation, the initial dose of Warfarin prescribed by clinicians is established as the baseline of our study. The experimental data collection consists of complete historical records of 587 inpatients who received Warfarin treatment. The overall evaluation results show that all of the learning based systems are significantly more accurate than the baseline. Among all prediction models, Bagging VOTE with four classifiers is suggested as the most effective prediction model due to its lower mean absolute errors (MAE) and variation of errors. The investigated models can not only facilitate clinicians in dosage decision-making, but also help reduce patient risk from adverse drug events.
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Wu, Meng-Lin, and 吳孟霖. "The Association of Warfarin Dosage in Clinical Use and Pharmacogenomics." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/05321073967456502525.

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碩士
國立臺灣大學
藥學研究所
94
Background Warfarin is an anticoagulant that is prescribed widely for the treatment and prevention of thrombosis. However, risks caused by warfarin vary, depending on the individuals, mainly genetic variations, environment, diseases and the severity of disease. It is important to adjust the dose of warfarin in clinical use based on the International Normalized Ratio (INR) value monitoring. All the possible factors involving dose adjustment will be investigated in this study in order to approach the individualized drug use. Methods Outpatients receiving long-term therapy were enrolled in National Taiwan University Hospital from July to October 2005. We collected the data including sex, age, indication, concomitant agents, INR value and the genotype of certain SNP sites in CYP1A2, CYP2C9, CYP2C19, CYP3A4, coagulation factor II, factor VII, factor IX, factor X, protein C, protein S, EPHX1, GGCX, GSTA1 and VKORC1. Furthermore, we detected the concentration of warfarin enantiomers and studied the association of pharmacogenomics and personalized warfarin doses. Results There were 75 patients enrolled in the study but two were excluded due to the failure of identifying the genotype. Deep vein thrombosis is the main indication in all patients. The mean maintenance dose was 3.9 mg/day and the mean INR value was 2.02. Results showed the variants of the positions -1639, 1173, 2225 in VKORC1 and the position 681 in CYP2C19 were highly related with warfarin maintenance dose. Also, there was negative relationship between age and warfarin maintenance dose in our study. Linkage disequilibrium of factor IX, GGCX and VKORC1 in certain SNP sites occurred in the study. The concentration of enantiomers was positively related to the maintenance dose of warfarin, but not to drug response. It is not applicable to adjustment of the dose by monitoring the concentration of racemic warfarin, or to its enantiomers. Conclusion The maintenance dose of warfarin was determined by multiple factors. The ethnic effect of Taiwanese and Caucasian might be partly caused by the different frequency of SNP sites of VKORC1 and CYP2C19. According to the regression model, we can calculate the warfarin maintenance dose by age and the genotype of these SNP sites so as to decrease the adverse drug effects and increase the safety of the drug.
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Wang, An-Li, and 王安利. "A Research of Generalized Linear Model in Warfarin Dosage Decisions." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/04559429061938288386.

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碩士
臺北市立大學
數學系數學教育碩士班統計組
102
Warfarin is the anti-coagulation and it is irreplaceable. Warfarin dose is affected by many factors, such as related drugs and diseases. Using warfarin has to be careful. If patients take inadequate doses, they will be blood clots. On the other hand, if patients take excessive doses, they will be bleeding. Currently, we refer to warfarin-used guide for Europeans and Americans in Taiwan, and there are few domestic papers about warfarin dose. In addition, it has not published a study of warfarin dose which is based on Chinese case history. Therefore, this research in warfarin dose is based on case history of patints who used warfarin in a perid in a large hospital. This data is composed of 87 patints, including 45 females and 42 males. Each patient getting warfarin prescription is counted as one sample, and the data amounts to 415 samples comprisig age, INR, related drugs and related diseases. Thence, it is a repeat measurement data, so using generalized estimating equations (GEE) to estimate warfarin dose in each case. The GEE results are found that (1) all related diseases we selected reduced dose about 0.1mg, (2) related drugs bring about 0.1mg of adjustment in dose at least. (3)As other conditions remain unchanged, the INR rise 1 degree, the average of warfarin dose takes more about 0.27mg - 0.28mg.
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Mitchell, Cathrine. "Evaluation of CYP2C9 and VKORC1 gene variants that may result in warfarin dosage sensitivity and poor pregnancy outcomes." Thesis, 2008. http://hdl.handle.net/10539/5757.

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Warfarin is the most widely prescribed oral anticoagulant used for the long-term treatment and prevention of thromboembolic events. Its administration is challenging as it may result in bleeding-related deaths, inadequate anticoagulation and fetal teratogenesis, including fetal warfarin syndrome. A number of environmental and genetic factors contribute to interindividual warfarin dosage variability. The CYP2C9 and VKORC1 genes explain 40- 50% of this variability. The aim of this study was to determine the frequency of known and any new variants in these genes in the SA black population, and correlate these variants and a small subset of environmental factors to dosage variability and pregnancy outcomes. I sequenced the exons and intron/exon boundaries of the CYP2C9 and VKORC1 genes in 100 random black control and 113 patient samples that had at least one pregnancy on warfarin. I observed six previously described CYP2C9 variants, 27 novel CYP2C9 variants, and three previously described VKORC1 variants. 14 of these variants were observed at an allele frequency of 0.02. Of these 14, six appear to decrease (all of which are CYP2C9 variants) and four increase (2 CYP2C9 variants and two VKORC1 variants) warfarin dosage requirement. These 14 CYP2C9 and VKORC1 variants along with a small subset of environmental factors account for 45.3% of warfarin dosage variability in the SA population. I observed an increase in the number of poor pregnancy outcomes in patients on high doses of warfarin. These results allow us to predict the maintenance dose of warfarin in SA black patients better, thereby reducing the risk of adverse effects, and identify those at risk of having a poor pregnancy outcome.
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Books on the topic "Warfarin dosage"

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J, Newton George, Inhalation Toxicology Research Institute, Sandia National Laboratories, and United States. Dept. of Energy, eds. Human radiation exposures related to nuclear weapons industries. Albuquerque, NM: Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, 1985.

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Rajakaruna, Senerat. A mathematical prediction of warfarin maintenance dosage. Bradford, 1987.

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Scott, Julie. The implementation and evaluation of a warfarin dosage protocol in orthopedic surgery patients. 2000.

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McDonald, Vickie, and Marie Scully. Anticoagulants and antithrombotics in critical illness. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0051.

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Coagulation is best thought of using the cell-based model of coagulation. Patients commenced on heparin therapy should have their platelet count monitored early because of the risk of heparin-induced thrombocytopenia, which can occur on any type or dose of heparin. Emergency reversal of warfarin should be with prothrombin complex concentrate (containing factors II, VII, IX, and X) and not fresh frozen plasma. New oral anticoagulants have the advantage of predictable pharmacokinetics and do not require routine monitoring, but optimal reversal strategies for these agents are not clear. Thrombolytic agents lead to variable degrees of systemic lysis, which may cause haemorrhage, including intracerebral haemorrhage
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Kilkelly, Shannon. Coagulation System. Edited by Matthew D. McEvoy and Cory M. Furse. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190226459.003.0090.

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Despite the development of entirely new classes of anticoagulant medication, vitamin K antagonists like warfarin continue to be commonly prescribed for a wide range of cardiovascular diagnoses. Conversely, the advent of low molecular weight heparin has greatly simplified the use of the drug to the point that patients can dose themselves at home with no need for any type of monitoring. Given the widespread use of these medications, it is not surprising that an increasing number of patients requiring urgent or emergent surgery will present with a medically induced coagulopathy. Managing this coagulopathy requires assessment of the urgency of the operation, the patient’s volume status, and the need for reanticoagulation following surgical intervention.
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Medicine, Institute of. An Evaluation of Radiation Exposure Guidance for Military Operations: Interim Report (Compass Series). National Academies Press, 1997.

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1945-, Mettler Fred A., Johnson J. Christopher, Thaul Susan, and Institute of Medicine (U.S.). Committee on Battlefield Radiation Exposure Criteria., eds. An evaluation of radiation exposure guidance for military operations: Interim report. Washington, D.C: National Academy Press, 1997.

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(US), National Research Council. Exposure of the American Population to Radioactive Fallout from Nuclear Weapons Tests: A Review of the CDC-NCI Draft Report on a Feasibility Study of the ... by the United States and Other Nations. National Academies Press, 2003.

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National Research Council (U.S.). Committee to Review the CDC-NCI Feasibility Study of the Health Consequences from Nuclear Weapons Tests, ed. Exposure of the American population to radioactive fallout from nuclear weapons tests: A review of the CDC-NCI draft report on a feasibility study of the health consequences to the American population from nuclear weapons tests conducted by the United States and other nations. Washington, D.C: National Academies Press, 2003.

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Book chapters on the topic "Warfarin dosage"

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Wessler, Stanford. "What’s the Dose?" In The New Dimensions of Warfarin Prophylaxis, 149–52. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4757-5985-3_11.

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Tao, Yanyun, Dan Xiang, Yuzhen Zhang, and Bin Jiang. "Swarm ANN/SVR-Based Modeling Method for Warfarin Dose Prediction in Chinese." In Lecture Notes in Computer Science, 351–58. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61833-3_37.

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Kang, Joonghee, Masato Sakon, and Jun-Ichi Kambayashi. "Reevaluation of Effectiveness of Low-Dose Warfarin as Antithrombotic Therapy After Vascular Reconstruction." In Modern Vascular Surgery, 424–29. New York, NY: Springer New York, 1994. http://dx.doi.org/10.1007/978-1-4612-2632-1_42.

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Yang, Lu, and Mark W. Linder. "Development of Predictive Models for Estimating Warfarin Maintenance Dose Based on Genetic and Clinical Factors." In Methods in Molecular Biology, 337–44. Totowa, NJ: Humana Press, 2013. http://dx.doi.org/10.1007/978-1-62703-435-7_22.

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Kapoor, Indu, Charu Mahajan, and Hemanshu Prabhakar. "Anesthesia in a Patient on Anticoagulant Dabigatran Presenting for Emergency Surgery." In Anesthesiology: A Problem-Based Learning Approach, edited by Tracey Straker and Shobana Rajan, 315–19. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190850692.003.0036.

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Dabigatran is an anticoagulant which acts by directly inhibiting the specific coagulation factors. It is used as a safe alternative to warfarin. This agent provides multiple benefits over warfarin which includes fixed dosing, lower incidence of hemorrhagic stroke, and no need of routine monitoring. Dabigatranetexilate (prodrug) is a direct thrombin inhibitor whereas rivaroxaban, edoxaban, and apixaban act by inhibiting factor Xa. Dabigatran is excreted through kidney (80%), so the dosage should be adjusted according to the creatinine clearance value. Life-threatening bleeding caused by dabigatran can be managed with its specific antidote idarucizumab to reverse its action. Factor 3 or 4 prothrombin concentrate complex may still be required in patients who bleed even after idarucizumab. Detailed knowledge about this medication can contribute to decrease in morbidity and improved outcome.
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Ezekowitz, Michael D., and Amanulla N. Khaji. "Stroke prevention in atrial fibrillation." In ESC CardioMed, 2185–95. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0514.

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Atrial fibrillation (AF) is a modern epidemic affecting the rapidly growing ageing population. Stroke related to AF can be devastating. The use of anticoagulation and more recently left atrial appendage occlusion devices makes stroke related to AF a potentially preventable event. Warfarin reduces stroke in completed trials against placebo by about 80%. Warfarin and apixaban, the only novel agent to be tested against aspirin, beats aspirin by about 50% and dual antiplatelet therapy by a similar margin. The novel agents dabigatran, rivaroxaban, apixaban, and edoxaban reduce strokes by 9–30% compared to warfarin. Approximately 80% of dabigatran is excreted by the kidneys (RE-LY trial), and dabigatran reduced the risk of stroke or systemic embolism compared to warfarin by 34% (p <0.001, superiority) for a 150 mg dose, and by 9% (p <0.001, non-inferiority) for a 110 mg dose. The risk of haemorrhagic stroke, compared to warfarin, was significantly lower with a 150 mg dose (74%) as well as with a 110 mg dose (69%). Gastrointestinal bleeding occurred more frequently in subjects who received 150 mg twice daily (1.51%/year) compared to 110 mg twice daily (1.12%/year) and warfarin (1.02%/year). Dyspepsia occurs in 5–10% of patents leading to permanent discontinuation in 2%.
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"Alterations to Warfarin Dose Maintenance Therapy." In Peripheral Brain for the Pharmacist, 2016 - 17. 2215 Constitution Avenue, NW, Washington, DC 20037-2985: The American Pharmacists Association, 2015. http://dx.doi.org/10.21019/9781582122403.ch7.

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"Alterations to Warfarin Dose Maintenance Therapy." In Peripheral Brain for the Pharmacist, 2017 - 18. 2215 Constitution Avenue, N.W. Washington, DC 20037-2985: The American Pharmacists Association, 2017. http://dx.doi.org/10.21019/9781582122885.warfarindosemaintenace.

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"Alterations to Warfarin Dose Maintenance Therapy (2 cards)." In Peripheral Brain for the Pharmacist, 2018 - 19. 2215 Constitution Avenue, N.W. Washington, DC 20037-2985: The American Pharmacists Association, 2018. http://dx.doi.org/10.21019/9781582123028.warfarindosemaintenace.

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Andreotti, Felicita, Eliano Pio Navarese, and Filippo Crea. "The NOACs in special situations: the elderly, renal impairment, combination with antiplatelet agents and thrombolytics." In ESC CardioMed, edited by Raffaele DeCaterina, 273–78. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0057.

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Phase III randomised trials indicate that the non-vitamin K antagonist oral anticoagulants (NOACs) are preferable to warfarin in elderly, non-valvular atrial fibrillation patients, given a lower incidence of intracranial haemorrhage, a favourable overall efficacy and safety profile, and the lack of routine monitoring, although care is needed to dose-adjust for kidney function and to prevent gastrointestinal bleeds, depending on the NOAC. Advanced age should not exclude the use of any NOAC. Overall, NOACs perform well, relative to warfarin or aspirin, irrespective of renal function. However, all NOACs undergo variable renal clearance, and in Europe a creatinine clearance of less than 30 mL/min contraindicates dabigatran and less than 15 mL/min the factor Xa inhibitors. Trial outcomes stratified by antiplatelet therapy, after adjustment for baseline risk, show that concomitant antiplatelet use does not significantly alter the overall treatment effects of NOACs versus warfarin. Whether adding an antiplatelet to a NOAC in atrial fibrillation patients with arterial disease is beneficial requires randomized controlled testing. Current guidelines recommend that patients effectively anticoagulated with a NOAC who develop an acute ischaemic stroke should not be considered for thrombolysis unless clinical history or laboratory tests indicate low or no anticoagulation or at least two half-lives have elapsed from the last NOAC dose. Retrospective data suggest no prohibitive adverse events among selected NOAC-treated patients with acute ischaemic stroke receiving thrombolysis. Further investigation in this setting is warranted.
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Conference papers on the topic "Warfarin dosage"

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Crow, M. J., A. B. Latif, A. I. Critchley, C. Stainton, P. Nealon, and S. M. Rajah. "COMPUTER PREDICTION OF ANTICOAGULATION STATUS AND WARFARIN DOSE FOLLOWING CARDIAC SURGERY." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643275.

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Fluctuations are freguently seen in the anticoagulant status of patients in the immediate post operative period following prosthetic heart valve replacement. These patients are at high risk of haemorrhage or thromboembolism. We have used a pharmokinetic model of warfarin metabolism to develop a computer programme to predict the maintenance dose of warfarin from early prothrombin activity determinations. This will enable controlled anticoagulation to be achieved. The expression for warfarin kinetics employs 4 constants determined by the residual sum of the sguares, which are used immediately to redefine dosage predictions. In a pilot study data obtained from 16 patients post operation 3, 5 and 7 days after commencing treatment, has been used to predict the reguired maintenance dose at 21 days. These predicted doses were then compared with the maintenance dose achieved by clinical practice. The programme was told to optimise its dose to achieve a PT ratio of 3 whereas clinically the ratio was allowed to vary in the therapeutic range of 2 to 4. Predicted doses at 21 days are shown.in the table:Correlation between predicted and clinical maintenance doses after 3 and 5 days treatment was poor but had improved significantly by 7 days, despite similar levels of prothrombin activity. Predicted prothrombin activity never exceeded the upper limit of the therapeutic range, and the predicted dose can be uprated on addition of further data within 2 minutes.After 7 days computer predicted warfarin dose has produced a good correlation with the clinical maintenance dose (the doses of only 3 patients varying by more than 1 mg/day). The significant fluctuations seen in the prothrombin ratio during clinical dosage were not observed with computer dosing and we now feel it is safe to use this programme to anticoagulate patients post operatively.
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Altay, Osman, Mustafa Ulas, Mahmut OZER, and Ece GENC. "An Expert System to Predict Warfarin Dosage in Turkish Patients Depending on Genetic and Non-Genetic Factors." In 2019 7th International Symposium on Digital Forensics and Security (ISDFS). IEEE, 2019. http://dx.doi.org/10.1109/isdfs.2019.8757526.

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Saeeda, Hina, and Muhammad Adil Abid. "An Ideology for the Prediction of Critical Haplotype Blocks of Variants in Genes (Cyp2c9 And Vkorc1) for Warfarin (Anticoagulant) Drug Dosage to Treat Heart Patients Efficiently by Using Ml (Machine Learning) and Data Stream Mining Techniques." In ICAIP 2019: 2019 3rd International Conference on Advances in Image Processing. New York, NY, USA: ACM, 2019. http://dx.doi.org/10.1145/3373419.3373424.

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McKernan, A., J. M. Thomson, and L. Poller. "A PROSPECTIVE RANDOMISED CONTROLLED STUDY OF MINI-DOSE WARFARIN PROPHYLAXIS OF DEEP VEIN THROMBOSIS IN MAJOR SURGERY." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643879.

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A prospective randomised study has been undertaken to assess the clinical effectiveness of oral anticoagulation using minidose warfarin (1 mg daily for 2-4 weeks before major gynaecological surgery) compared with conventional oral anticoagulant prophylaxis and an untreated randomised control group. The conventional oral anticoagulant prophylaxis was based on a therapeutic range of 1.5 - 2.0 INR at the time of operation and 2.0 - 3.0 INR post-operatively. Overall the mini-dose warfarin group showed no pre-operative prolongation of the prothrombin time with the Manchester Reagent although a minority of patients showed a 1-2 second prolongation of the prothrombin time before operation. Post operatively the mini-dose warfarin group showed an exaggerated prolongation of the prothrombin time which normally occurs after operation and was observed in the untreated controls. Factor VII assays paralleled these findings. Minidose warfarin, while not prolonging the prothrombin time before operation, resulted in delayed platelet aggregation with the Chandler's tube technique in almost all patients.The incidence of deep vein thrombosis has been reduced in both mini-dose and conventional dose oral anticoagulant series compared with the untreated- group. It appears that the minimal changes in the prothrombin time, factor VII and platelet aggregation tests, observed in the mini-dose warfarin group, may offer sufficient protection against post-operative thrombosis in a moderate risk group undergoing abdominal or pelvic surgery.
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Powers, P. J., M. Gent, R. Jay, J. Hirsh, M. Levine, and G. Turpie. "DEEP VEIN THROMBOSIS PROPHYLAXIS IN SURGICALLY TREATED FRACTURED HIP PATIENTS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643692.

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Deep vein thrombosis is a major complication in'patients treated surgically for fractured hip. Methods employed toreduce the risk of thrombosis include dextran, ASA, warfarin, low or adjusted dose heparin and calf compression, but none has widespread acceptance.A randomized trial wascarried out to assess the effectiveness of sodium warfarinand acetyl salicylic acid(aspirin) compared to placebo inthe prevention of venous thrombosis in fractured hip patients. One hundred and ninty four patients were randomizedto receive warfarin (65 patients), ASA (66 patients) or placebo (63 patients).Prophylaxis commenced post operatively and continued for 21 days or until discharge, if earlier.Warfarin patients received 10 mg sodium warfarin orally as soon as possible after surgery. Warfarin was then given daily according to the prothrombin time (PT), to obtain a PT of 16 seconds on the 5th post operative day. The PT was maintain at 16 to 18 seconds until the end of treatment.ASA and placebo patients received enteric coated tablets, 650 mg twice daily, in a double blind fashion beginning as soon as possible post operatively and continuingto the end of treatment. Surveillance testing and I-fibrinogen leg scanning and impedance plethysmography was performed and venography was done if either test suggested thrombus at the popliteal vein or above. Otherwise venography was performed at day 21 or prior to discharge, if earlier. Venous thrombosis occurred in 13 patients (20%) in the warfarin group, 27 patients (^0.9%) in the ASA group, and 29 patients (46%) in the placebo group (P=0.005). Proximal vein thrombosis or pulmonary embolism occurred in 6patients (9.2%) in the warfarin group,7 patients (10.6%) in the ASA and 19 patients (30.2%) in the placebo group (P=0.002). Two major hemorrhages occurred in the warfarin group, none in the ASA group, and 2 in the placebo group.The results of this study show sodium warfarin to be safeand effective in reducing thromboembolic complications infractured hip patients and ASA to be effective in reducing thrombosis involving the proximal deep veins of the lower limbs in these patients.
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Wang, Zeyuan, Josiah Poon, Jie Yang, and Simon Poon. "Warfarin Dose Estimation on High-dimensional and Incomplete Data." In Hawaii International Conference on System Sciences. Hawaii International Conference on System Sciences, 2021. http://dx.doi.org/10.24251/hicss.2021.419.

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Gerna, M., and M. B. Donati. "HYPERCOAGULABILITY AND REDUCED SENSITIVITY TO WARFARIN IN RATS FOLLOWING CAFFEINE INTAKE." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643399.

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The effect(s) of caffeine Intake on cardiovascular functions are still a matter of debate. We have considered here the level of the prothrombin complex activity as a parameter of blood coagulability following caffeine Intake. The activity of the four vitamin K-dependent clotting factors (II, VII, IX and X) was tested after acute and chronic administration of high doses of caffeine. With a single administration of 50 mg/kg caffeine a statistically significant increase in the activity of factors VII, IX and X was observed. The increase lasted for 4, 3 and 2 days respectively. Factor II was not affected by caffeine administration. The same effect was observed during chronic administration (50 mg/kg/day). With a lower dose of caffeine during chronic administration (5 mg/kg/day) only factor X showed a significant increase. A single dose of caffeine (50 mg/kg) given to animals 24h before-a dose of warfarin (0.4 mg/kg i.v.) markedly reduced the anticoagulant effect of warfarin, as measured by the thrombotest. During the latter experiment we measured also the rate of synthesis (Rsyn) of the prothrombin complex activity. Rsyn, during warfarin treatment, was significantly higher in the rats pretreated with caffeine than In controls. γ-Carboxylase activity in rat liver mlcrosomes was measured after administration of 50 mg/kg of caffeine as a single dose. The Incorporation of 14CO2 in the endogenous precursor was higher in the rats pretreated with caffeine than In controls (84,905 cpm/mg of protein versus 59,826 cpm/mg of proteins); this difference, however, was not statistically significant. In conclusion, caffeine jntake may affect the clotting system mainly by stimulating the synthesis of factors of the prothrombin complex and, as a consequence, their response to coumarin anticoagulation.
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Tao, Yanyun, Yuzhen Zhang, and Bin Jiang. "Evolutionary learning-based modeling for warfarin dose prediction in Chinese." In GECCO '17: Genetic and Evolutionary Computation Conference. New York, NY, USA: ACM, 2017. http://dx.doi.org/10.1145/3067695.3082492.

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Karpurapu, Anish, Adam Krekorian, Ye Tian, Leslie M. Collins, Ravi Karra, Aaron D. Franklin, and Boyla O. Mainsah. "Evaluating the Effect of Longitudinal Dose and INR Data on Maintenance Warfarin Dose Predictions." In 2021 IEEE EMBS International Conference on Biomedical and Health Informatics (BHI). IEEE, 2021. http://dx.doi.org/10.1109/bhi50953.2021.9508510.

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Rackauskiene, Jolita, Vaida Gedvilaite, Mindaugas Mataciunas, Mazvile Abrutyte, Olga Kusner, and Edvardas Danila. "Therapeutic warfarin dose dependence on age and smoking in acute pulmonary embolism." In Annual Congress 2015. European Respiratory Society, 2015. http://dx.doi.org/10.1183/13993003.congress-2015.pa700.

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Reports on the topic "Warfarin dosage"

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Oh, SangHyeon, Seoyong Choi, and Jee-Eun Chung. Comparative efficacy and safety of reduced dose of DOACs in patients with atrial fibrillation. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, August 2022. http://dx.doi.org/10.37766/inplasy2022.8.0073.

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Review question / Objective: To compare the risk of stroke/systemic embolism (S/SE), mortality and bleeding in AF patients with reduced-dose DOACs. Rationale: Although each DOAC has its dose reduction criteria, many physicians still prefer to prescribe the reduced-dose DOACs, regardless of label adherence. However, inappropriate administration of DOACs is an important clinical problem because patients may not benefit from the recommended DOAC dose to prevent stroke and systemic embolism. Therefore, this study aims to investigate the risk of stroke/systemic embolism (S/SE) and mortality in AF patients with reduced-dose DOACs. Condition being studied: Adult patients with AF taking DOACs or Warfarin.
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