| 121. |
- van Schie, Rianne M. F., et al.
(författare)
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Genotype-guided dosing of coumarin derivatives : the European pharmacogenetics of anticoagulant therapy (EU-PACT) trial design
- 2009
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Ingår i: Pharmacogenomics (London). - : Future Medicine Ltd. - 1462-2416 .- 1744-8042. ; 10:10, s. 1687-1695
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Tidskriftsartikel (refereegranskat)abstract
- The narrow therapeutic range and wide interpatient variability in dose requirement make anticoagulation response to coumarin derivatives unpredictable. As a result, patients require frequent monitoring to avert adverse effects and maintain therapeutic efficacy. Polymorphisms in VKORC1 and CYP2C9 jointly account for about 40% of the interindividual variability in dose requirements. To date, several pharmacogenetic-guided dosing algorithms for coumarin derivatives, predominately for warfarin, have been developed. However, the potential benefit of these dosing algorithms in terms of their safety and clinical utility has not been adequately investigated in randomized settings. The European Pharmacogenetics of Anticoagulant Therapy (EU-PACT) trial will assess, in a single-blinded and randomized controlled trial with a follow-up period of 3 months, the safety and clinical utility of genotype-guided dosing in daily practice for the three main coumarin derivatives used in Europe. The primary outcome measure is the percentage time in the therapeutic range for international normalized ratio. This report describes the design and protocol for the trial.
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| 122. |
- Verhoef, Talitha I., et al.
(författare)
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A Randomized Trial of Genotype-Guided Dosing of Acenocoumarol and Phenprocoumon
- 2013
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 369:24, s. 2304-2312
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Tidskriftsartikel (refereegranskat)abstract
- Background: Observational evidence suggests that the use of a genotype-guided dosing algorithm may increase the effectiveness and safety of acenocoumarol and phenprocoumon therapy.Methods: We conducted two single-blind, randomized trials comparing a genotype-guided dosing algorithm that included clinical variables and genotyping for CYP2C9 and VKORC1 with a dosing algorithm that included only clinical variables, for the initiation of acenocoumarol or phenprocoumon treatment in patients with atrial fibrillation or venous thromboembolism. The primary outcome was the percentage of time in the target range for the international normalized ratio (INR; target range, 2.0 to 3.0) in the 12-week period after the initiation of therapy. Owing to low enrollment, the two trials were combined for analysis. The primary outcome was assessed in patients who remained in the trial for at least 10 weeks.Results: A total of 548 patients were enrolled (273 patients in the genotype-guided group and 275 in the control group). The follow-up was at least 10 weeks for 239 patients in the genotype-guided group and 245 in the control group. The percentage of time in the therapeutic INR range was 61.6% for patients receiving genotype-guided dosing and 60.2% for those receiving clinically guided dosing (P=0.52). There were no significant differences between the two groups for several secondary outcomes. The percentage of time in the therapeutic range during the first 4 weeks after the initiation of treatment in the two groups was 52.8% and 47.5% (P=0.02), respectively. There were no significant differences with respect to the incidence of bleeding or thromboembolic events.Conclusions: Genotype-guided dosing of acenocoumarol or phenprocoumon did not improve the percentage of time in the therapeutic INR range during the 12 weeks after the initiation of therapy.
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| 123. |
- Verhoef, Talitha I, et al.
(författare)
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A systematic review of cost-effectiveness analyses of pharmacogenetic-guided dosing in treatment with coumarin derivatives.
- 2010
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Ingår i: Pharmacogenomics (London). - : Future Medicine Ltd. - 1462-2416 .- 1744-8042. ; 11:7, s. 989-1002
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Tidskriftsartikel (refereegranskat)abstract
- Anticoagulant therapy with coumarin derivatives is often sub- or supra-therapeutic, resulting in an increased risk of thromboembolic events or hemorrhage, respectively. Pharmacogenetic-guided dosing has been proposed as an effective way of reducing bleeding rates. Clinical trials to confirm the safety, efficacy and effectiveness of this strategy are ongoing, but in addition, it is also necessary to consider the cost-effectiveness of this strategy. This article describes the findings of a systematic review of published cost-effectiveness analyses of pharmacogenetic-guided dosing of coumarin derivatives. Similarities and differences in the approaches used were examined and the quality of the analyses was assessed. The results of the analyses are not sufficient to determine whether or not pharmacogenetic-guided dosing of coumarins is cost effective. More reliable cost-effectiveness estimates need to become available before it is possible to recommend whether or not this strategy should be applied in clinical practice.
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| 124. |
- Verhoef, T. I., et al.
(författare)
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Cost-effectiveness of pharmacogenetic-guided dosing of warfarin in the United Kingdom and Sweden
- 2016
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Ingår i: The Pharmacogenomics Journal. - : Springer Science and Business Media LLC. - 1470-269X .- 1473-1150. ; 16:5, s. 478-484
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to assess the cost-effectiveness of pharmacogenetic-guided dosing of warfarin in patients with atrial fibrillation (AF) in the United Kingdom and Sweden. Data from EU-PACT, a randomized controlled trial in newly diagnosed AF patients, were used to model the incremental costs per quality-adjusted life-year (QALY) gained by pharmacogenetic-guided warfarin dosing versus standard treatment over a lifetime horizon. Incremental lifetime costs were £26 and 382 Swedish kronor (SEK) and incremental QALYs were 0.0039 and 0.0015 in the United Kingdom and Sweden, respectively. The corresponding incremental cost-effectiveness ratios (ICERs) were £6 702 and 253 848 SEK per QALY gained. The ICER was below the willingness-to-pay threshold of £20 000 per QALY gained in 93% of the simulations in the United Kingdom and below 500 000 SEK in 67% of the simulations in Sweden. Our data suggest that pharmacogenetic-guided dosing of warfarin is a cost-effective strategy to improve outcomes of patients with AF treated with warfarin in the United Kingdom and in Sweden.
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| 125. |
- Verhoef, Talitha I, et al.
(författare)
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Cost-effectiveness of pharmacogenetics in anticoagulation: international differences in healthcare systems and costs
- 2012
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Ingår i: Pharmacogenomics (London). - : Future Medicine. - 1462-2416 .- 1744-8042. ; 13:12, s. 1405-1417
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Forskningsöversikt (refereegranskat)abstract
- Genotyping patients for CYP2C9 and VKORC1 polymorphisms can improve the accuracy of dosing during the initiation of anticoagulation with vitamin K antagonists (coumarin derivatives). The anticipated degree of improvement in the safety of anticoagulation with coumarins through genotyping may vary depending on the quality of patient care, which varies both with and among countries. The management and the cost of anticoagulant care can therefore influence the cost effectiveness of genotyping within any given country. In this article, we provide an overview of the cost effectiveness of pharmacogenetics-guided dosing of coumarin derivatives. We describe the organization of anticoagulant care in the UK, Sweden, The Netherlands, Greece, Germany and Austria, where a genotype-guided dosing algorithm is currently being investigated as part of the EU-PACT trial. We also explore the costs of anticoagulant care for the treatment of atrial fibrillation in these countries.
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| 126. |
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| 127. |
- Wadelius, Mia, et al.
(författare)
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Induction of CYP2D6 in pregnancy
- 1997
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Ingår i: Clinical Pharmacology and Therapeutics. - 0009-9236 .- 1532-6535. ; 62:4, s. 400-7
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the drug-metabolizing enzyme cytochrome P4502D6 (CYP2D6) is predominantly under genetic control, and enzyme-inducing drugs have little influence on its activity. We studied the activity of CYP2D6 during pregnancy. One hundred forty pregnant women were genotyped for CYP2D6. Seventeen of them (four poor metabolizers, seven heterozygous extensive metabolizers, and six extensive metabolizers) were phenotyped with dextromethorphan in late pregnancy and 7 to 11 weeks after parturition. During pregnancy the dextromethorphan/dextrorphan metabolic ratio was significantly reduced (p = 0.0015) among homozygous and heterozygous extensive metabolizers, indicating increased CYP2D6 activity. In contrast, poor metabolizers showed an increased metabolic ratio during pregnancy. These results are consistent with previous findings of a marked increase in metabolism of the CYP2D6 substrate metoprolol during pregnancy. Both studies indicate an increase in CYP2D6 activity during pregnancy, which may be caused by an induction of the CYP2D6 enzyme.
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| 128. |
- Wadelius, Mia
(författare)
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Pharmacogenetic analysis in sickness and in health - for better or for worse
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An individual's pharmacogenetic constitution may predict response to drugs, hormones and toxins, and might be a susceptibility factor for disease. Pharmacogenetic diversity is especially pronounced for drug metabolising enzymes. In these studies the following five enzymes have been genotyped: N-acetyltransferase 2 (NAT2), sparteine/debrisoquine hydroxylase (CYP2D6), mephenytoin hydroxylase (CYP2C19), steroid 17α-hydroxylase (CYP17), and glutathione S-transferase P1 (GSTP1).A simplified method for genotyping NAT2 was verified by phenotyping with isoniazid. All phenotypes: slow, intermediate and fast acetylators were correctly identified by genotyping. This method was used to genotype control subjects and patients who reacted to sulphasalazine with agranulocytosis. The incidence of slow acetylation was equal in agranulocytosis patients and population-based controls. However, the incidence of slowacetylation was significantly reduced in patients who tolerated sulphasalazine compared with both agranulocytosis patients and population-based controls.Different genotypes of the enzymes NAT2, CYP2D6, CYP2C19, GSTP1 and CYP17 were studied as possible susceptibility factors for prostate cancer in a case-control study. No association was found between prostate cancer and NAT2, CYP2D6, CYP2C19 orGSTP1 genotypes. A certain genotype of CYP17, encoding a key enzyme in testosterone synthesis, was associated with prostate cancer, a finding that warrants further studies. CYP2D6 is not considered to be an inducible enzyme, but phenotyping of pregnant women showed that CYP2D6 activity is increased during pregnancy. This may be caused by enzyme induction, suggesting possible impact on drug treatment during pregnancy. In the future, as more pharmacogenetic information becomes available, predicting individual drug responses will become an essential part of therapy.
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| 129. |
- Wadelius, Mia, et al.
(författare)
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Pharmacogenetics of warfarin : current status and future challenges
- 2007
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Ingår i: The Pharmacogenomics Journal. - : Springer Science and Business Media LLC. - 1470-269X .- 1473-1150. ; 7:2, s. 99-111
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Forskningsöversikt (refereegranskat)abstract
- Warfarin is an anticoagulant that is difficult to use because of the wide variation in dose required to achieve a therapeutic effect, and the risk of serious bleeding. Warfarin acts by interfering with the recycling of vitamin K in the liver, which leads to reduced activation of several clotting factors. Thirty genes that may be involved in the biotransformation and mode of action of warfarin are discussed in this review. The most important genes affecting the pharmacokinetic and pharmacodynamic parameters of warfarin are CYP2C9 (cytochrome P(450) 2C9) and VKORC1 (vitamin K epoxide reductase complex subunit 1). These two genes, together with environmental factors, partly explain the interindividual variation in warfarin dose requirements. Large ongoing studies of genes involved in the actions of warfarin, together with prospective assessment of environmental factors, will undoubtedly increase the capacity to accurately predict warfarin dose. Implementation of pre-prescription genotyping and individualized warfarin therapy represents an opportunity to minimize the risk of haemorrhage without compromising effectiveness.
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| 130. |
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