Protein Information

Name prothrombin
Synonyms Coagulation factor II; Coagulation factor II variant; F2; F2 protein; F2 protein precursor; Factor II; PT; Prothrombin…

Compound Information

Name warfarin
CAS

Reference List

PubMed Abstract RScore(About this table)
18373620 Dargaud Y, Desmurs-Clavel H, Marin S, Bordet JC, Poplavsky JL, Negrier C: Comparison of the capacities of two prothrombin complex concentrates to restore thrombin generation in plasma from orally anticoagulated patients: an in vitro study. Pol Merkur Lekarski. 2008 May;24(143):458-62.

BACKGROUND: Human prothrombin complex concentrates (PCCs) are used for prevention and treatment of bleeding episodes in patients under warfarin therapy.
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18778188 Nishio H, Ieko M, Nakabayashi T: New therapeutic option for thromboembolism--dabigatran etexilate. Ann Pharmacother. 2008 May;42(5):680-5. Epub 2008 Apr 15.

New orally available anticoagulant agents with a wide therapeutic window are keenly anticipated because warfarin and heparins have some disadvantages, and recent progress in pharmaceutical techniques has led to the development of orally administered direct thrombin inhibitors.
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18494194 Glasnovic M, Bosnjak I, Vcev A, Soldo I, Bedekovic D, Milakovic S, Hecimovic V, Horvatic E, Bardek M: Vascular thrombosis associated with antiphospholipide syndrome. Scand J Clin Lab Invest. 2007 Dec 21:1-4.

Administered therapy was low molecular weight heparin (LMWH) throughout 7 days, followed by warfarin with prothrombin time maintained between 2.0 and 3.0 INR.
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19477376 Miura T, Nishinaka T, Terada T, Yonezawa K: Relationship between aging and dosage of warfarin: The current status of warfarin anticoagulant therapy for Japanese outpatients in a department of cardiovascular medicine. J Cardiol. 2009 Jun;53(3):355-60. Epub 2009 Feb 8.

METHODS: The subjects comprised 102 outpatients (28-87 years) who showed a stable anticoagulant effect (prothrombin time expressed in terms of the international normalized ratio [PT-INR] between 1.6 and 2.6) following long-term warfarin therapy at the Department of Cardiovascular Medicine, National Hospital Organization Hakodate Hospital.
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19644604 Nowak G: [New anticoagulants for secondary haemostasis--anti IIa inhibitors] . Hamostaseologie. 2009 Aug;29(3):256-9.


In contrast to heparins and oral anticoagulants, anti IIa inhibitors (thrombin inhibitors) are able to directly inhibit the protease activity of thrombin and can thereby precisely control the blood coagulation process.
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19338378 Hursting MJ, Soffer J: Reducing harm associated with anticoagulation: practical considerations of argatroban therapy in heparin-induced thrombocytopenia. Blood. 2009 Nov 19;114(21):4741-8. Epub 2009 Sep 30.

Argatroban is a hepatically metabolized, direct thrombin inhibitor used for prophylaxis or treatment of thrombosis in heparin-induced thrombocytopenia (HIT) and for patients with or at risk of HIT undergoing percutaneous coronary intervention (PCI).
Argatroban prolongs the International Normalized Ratio, and published approaches for monitoring the argatroban-to-warfarin transition should be followed.
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19198584 Cheng J, Vemula N, Gendler S: Small bowel obstruction caused by intramural hemorrhage secondary to anticoagulant therapy. Clin Cardiol. 2008 Feb;31(2):55-62.

An 85-year-old male patient with atrial fibrillation on long-term warfarin presented with nausea and vomiting for 2 days, accompanied with no bowel movement since the onset.
Investigations showed anemia with hemoglobin/ hematocrit of 10 (g/dl) / 30%, prothrombin time with an International Normalized Ratio (INR) of 9.58.
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19620700 Hamel-Desnos CM, Gillet JL, Desnos PR, Allaert FA: Sclerotherapy of varicose veins in patients with documented thrombophilia: a prospective controlled randomized study of 105 cases. Thromb Haemost. 2010 Mar 1;103(3):572-85. Epub 2010 Feb 2.

OBJECTIVES: The aim of this study was to assess thrombotic complications following sclerotherapy in thrombophilic patients in combination with thromboprophylaxis, in two randomized arms using low molecular weight heparin (LMWH) or warfarin.
A total of 105 patients (81 females, 24 males) ranging in age from 20 to 82 years (mean 50) were selected: 75 with Factor V Leiden mutation, 18 with prothrombin 20210A mutation, 7 with high level of Factor VIII, 5 combinations of these.
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19378859 Brejcha M, Gumulec J, Penka M, Klodova D, Wrobel M, Bogoczova E: [Preparation of patients on anticoagulant treatment for invasive surgery] . J Thromb Thrombolysis. 2010 Feb 16.

The management of warfarin therapy in patients undergoing surgery or other invasive procedures involves a balance between the risk of hemorrhage, and the risk of thrombosis.
In patients requiring emergency surgery, vitamin K, prothrombin complex concentrate or fresh frozen plasma can be used to improve coagulation.
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18428048 Favaloro EJ, Hamdam S, McDonald J, McVicker W, Ule V: Time to think outside the box? Prothrombin time, international normalised ratio, international sensitivity index, mean normal prothrombin time and measurement of uncertainty: a novel approach to standardisation. IDrugs. 1998 May;1(1):13-6.

BACKGROUND: The prothrombin time (PT) assay is the most clinically ordered coagulation test, and most often used for monitoring of vitamin K antagonist therapy (e.g., warfarin), where results are expressed as an international normalised ratio (INR).
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18716776 Kamali F, Wood P, Ward A: Vitamin K deficiency amplifies anticoagulation response to ximelagatran: possible implications for direct thrombin inhibitors and their clinical safety. J Thromb Haemost. 2008 Jun;6(6):962-8. Epub 2008 Mar 27.

Ximelagatran and warfarin increased prothrombin time (PT) by 1.4- and 1.3-fold, activated partial thromboplastin time (APTT) by 1.8- and 1.4-fold and ecarin clotting time (ECT) by 6.8- and 1.2-fold, respectively, in rats on normal diet.
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19817159 Holmstrom M: [Prothrombin complex concentrate important in warfarin induced hemorrhage] Phlebology. 2009 Aug;24(4):176-82.
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19663670 Sasaki T, Tabuchi H, Higuchi S, Ieiri I: Warfarin-dosing algorithm based on a population pharmacokinetic/pharmacodynamic model combined with Bayesian forecasting. Clin Drug Investig. 2009;29(1):35-50. doi: 10.2165/0044011-200929010-00004.

MATERIALS & METHODS: Using information on CYP2C9 and VKORC1 genotypes, S-warfarin level, dose and international normalized ratio (INR) of prothrombin time, individual PK (apparent clearance of S-warfarin [CLs]) and PD (concentration resulting in 50% of E (max) [EC (50)]) parameters were determined by Bayesian forecasting for 45 Japanese patients.
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19172700 Enstrom C, Osman A, Lindahl TL: A genotyping method for VKORC1 1173C > T by Pyrosequencing technology. Curr Treat Options Cardiovasc Med. 2008 Sep;10(5):388-97.

The SNP rs9934438 in intron 1 of VKORC1 (c.173+1000C > T or 1173C > T) discriminating the VKORC1*2 haplotype is associated with low warfarin dose requirement and unstable prothrombin time - international normalized ratio.
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20201481 Friedman RJ: New oral anticoagulants for thromboprophylaxis after total hip or knee arthroplasty. Cutan Ocul Toxicol. 2008;27(1):29-40.

Conventional anticoagulants have several short-comings: for example, warfarin requires regular coagulation monitoring and low-molecular-weight heparins are inconvenient to use because they require subcutaneous administration.
The development of new anticoagulants has focused on 2 classes of compounds: direct thrombin inhibitors and direct factor Xa inhibitors.
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18549907 Wiedermann CJ, Stockner I: Warfarin-induced bleeding complications - clinical presentation and therapeutic options. Transfusion. 2009 Dec;49(12):2652-60. Epub 2009 Aug 4.

Currently available therapeutic options for the reversal of OAC include vitamin K for non-emergency situations and fresh frozen plasma (FFP) and coagulation factor concentrates such as prothrombin complex concentrate (PCC) for urgent situations.
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19923313 Moretti LV, Montalvo RO: Elevated International Normalized Ratio associated with concurrent use of sorafenib and warfarin. J Thromb Haemost. 2008 Oct;6(10):1750-6. Epub 2008 Jul 28.

The patient arrived at the emergency room one month later with a prothrombin time (PT) of 84.8 and an INR value of 39.5.
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20040270 Zikria J, Ansell J: Oral anticoagulation with Factor Xa and thrombin inhibitors: Is there an alternative to warfarin?. Liver Int. 2008 Dec;28(10):1325-7.
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18706082 Bruce D, Nokes TJ: Prothrombin complex concentrate (Beriplex P/N) in severe bleeding: experience in a large tertiary hospital. J Cardiovasc Pharmacol. 2008 Jul;52(1):18-27.

We investigated the use of a prothrombin complex concentrate (PCC; Beriplex P/N, CSL Behring, Marburg, Germany) to treat severe bleeding in a variety of settings: cardiac surgery, warfarin therapy and other surgery.
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19085760 Favaloro EJ, Adcock DM: Standardization of the INR: how good is your laboratory's INR and can it be improved?. Lakartidningen. 2009 Sep 9-15;106(37):2270.

The prothrombin time (PT) assay is the most clinically ordered coagulation test and is most often used for monitoring of vitamin K antagonist (VKA) therapy (e.g., warfarin), where results are expressed as an international normalized ratio (INR).
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20339978 Ozer N, Cam N, Tangurek B, Ozer S, Uyarel H, Oz D, Guney MR, Ciloglu F: The impact of CYP2C9 and VKORC1 genetic polymorphism and patient characteristics upon warfarin dose requirements in an adult Turkish population. Clin Chem Lab Med. 2009;47(5):503-15.

Blood samples were collected from 100 Turkish patients with stable warfarin dose requirements and an international normalized ratio (INR) of the prothrombin time within the therapeutic range.
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20182349 Rosborough TK, Jacobsen JM, Shepherd MF: Factor X and factor II activity levels do not always agree in warfarin-treated lupus anticoagulant patients. Heart Vessels. 2010 Mar;25(2):155-62. Epub 2010 Mar 26.

Warfarin therapy is used in lupus anticoagulant patients with thrombosis and yet the prothrombin time (PT)/international normalized ratio (INR) in these patients can sometimes be falsely elevated.
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18520598 Uno T, Sugimoto K, Sugawara K, Tateishi T: The role of cytochrome P2C19 in R-warfarin pharmacokinetics and its interaction with omeprazole. Can J Anaesth. 2010 Jan 15.

The plasma concentrations of warfarin enantiomers and prothrombin time expressed as international normalized ratio were monitored up to 120 hours.
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18637764 Lee SH, Ahn YM, Ahn SY, Doo HK, Lee BC: Interaction between warfarin and Panax ginseng in ischemic stroke patients. Discov Med. 2009 Dec;8(43):196-203.

RESULTS: The peak values and the international normalized ratio (INR) and prothrombin time (PT) areas under the curve (AUC) in both groups significantly increased compared to those at baseline.
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18634396 Sawicka-Powierza J, Rogowska-Szadkowska D, Oltarzewska AM, Chlabicz S: [Factors influencing activity of oral anticoagulants. Circ J. 2009 Jul;73(7):1319-23. Epub 2009 May 12.

A mutation in the factor IX is responsible for the risk of bleeding during OAC therapy without excessive prolongation of the prothrombin time (PT).
A common mutation in the gene coding for the cytochrome P450 (CYP2C9), with one or more combinations of its polymorphisms, is responsible for the reduced warfarin requirements or for the resistance to warfarin.
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20135753 Chan VH, Monagle P, Massicotte P, Chan AK: Novel paediatric anticoagulants: a review of the current literature. Blood Coagul Fibrinolysis. 2008 Sep;19(6):609-10.

There are many limitations with respect to anticoagulants currently used in standard paediatric practice for prophylaxis and treatment of thrombosis: heparin, low molecular-weight heparin, and warfarin.
In this review, we discuss several promising direct thrombin inhibitors and factor Xa inhibitors, and synthesize relevant drug information and clinical experience from the limited available case reports, case series, and nonrandomized dose-finding trials published to date.
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19665679 Ng VL: Anticoagulation monitoring. Semin Respir Crit Care Med. 2008 Feb;29(1):66-74.

This article reviews the commonly used anticoagulants (warfarin and heparin) and associated recommended laboratory testing.
The newer anticoagulants (heparin analogs, direct factor Xa inhibitors, and direct thrombin inhibitors) and various applied coagulation laboratory testing and related issues are also discussed.
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19338267 Sandblad P, Arnell R, Samuelsson J, Fornstedt T: Approach for reliable evaluation of drug proteins interactions using surface plasmon resonance technology. Hematology Am Soc Hematol Educ Program. 2008:259-65.

The binding of the enantiomers of the thrombin inhibitor melagatran was investigated on both thrombin and the transport proteins, revealing clear enantioselectivity for thrombin in favor of the active enantiomer, but almost similar binding properties for both enantiomers to the transport protein AGP.
Both the binding of the chiral beta-blocker propranolol to alpha (1)-acid glycoprotein (AGP) and that of the anticoagulant warfarin to human serum albumin were heterogeneous, with a few strong enantioselective sites and many weak nonselective sites.
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18375602 Rawat A, Huynh TT, Peden EK, Kougias P, Lin PH: Primary prophylaxis of venous thromboembolism in surgical patients. Vasc Endovascular Surg. 2008 Jun-Jul;42(3):205-16. Epub 2008 Mar 28.

Pharmacological prophylaxis for venous thromboembolism includes unfractionated heparin, low-molecular weight heparin, fondaparinux, warfarin, antiplatelet therapy, and direct thrombin inhibitors.
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20170841 Hankey GJ, Eikelboom JW: Antithrombotic drugs for patients with ischaemic stroke and transient ischaemic attack to prevent recurrent major vascular events. Can J Anaesth. 2010 Mar 20.

The direct thrombin inhibitor, dabigatran etexilate, has shown efficacy over warfarin in a recent trial.
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20353743 Roncon-Albuquerque R Jr, Beco A, Ferreira AL, Gomes-Carvalho C, Costa A, Frazao J, Pestana M, von Hafe P: Therapeutic implications of heparin-induced thrombocytopenia complicating acute hemodialysis. J Toxicol Sci. 2008 Aug;33(3):283-91.

All sources of heparin were discontinued and alternative anticoagulation was initiated with argatroban, a direct-thrombin inhibitor with hepatic clearance, followed by transition to warfarin.
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19687493 Rosove MH, Grody WW: Should we be applying warfarin pharmacogenetics to clinical practice? No, not now. Vasc Health Risk Manag. 2010 Mar 3;6:95-103.

Careful consideration of clinical factors that influence dosing, conscientious prothrombin time monitoring, and sage dosage adjustment remain paramount in warfarin management.
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19135231 Yoshizawa M, Hayashi H, Tashiro Y, Sakawa S, Moriwaki H, Akimoto T, Doi O, Kimura M, Kawarasaki Y, Inoue K, Itoh K: Effect of VKORC1-1639 G> A polymorphism, body weight, age, and serum albumin alterations on warfarin response in Japanese patients. Pediatr Blood Cancer. 2009 Sep;53(3):468-71.

We selected 259 patients who have been prescribed warfarin with a 1.5-3.0 range of prothrombin time normalized as an international normalized ratio for at least 3 months and investigated factors that contribute to individual variability in warfarin dose.
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19740099 Gilmore R, Harmon S, Keane G, Gannon C, O'Donnell JS: Variation in anticoagulant composition regulates differential effects of prothrombin complex concentrates on thrombin generation. Coll Antropol. 2008 Jun;32(2):557-64.

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19454860 Schwartz JI, Liu F, Stroh M, Gipson A, Johnson-Levonas AO, Lasseter KC, Lai E, Wagner JA: Influence of laropiprant, a selective prostaglandin D2 receptor 1 antagonist, on the pharmacokinetics and pharmacodynamics of warfarin. Thromb Haemost. 2010 Mar 1;103(3):604-12. Epub 2010 Jan 13.

The estimated GMRs of area under the prothrombin time INR curve from 0 to 168 hours on day 21 (INR AUC0-168 h) and average maximum observed prothrombin time INR (INRmax) were 1.02 (0.99, 1.05) and 1.04 (0.98, 1.10), respectively.
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18264606 Jacobson B: At last--the end of the prothrombin index. Adv Ther. 2008 Nov;25(11):1175-90.

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18656871 Stein DM, Dutton RP, Hess JR, Scalea TM: Low-dose recombinant factor VIIa for trauma patients with coagulopathy. . J Thromb Haemost. 2008 Aug;6(8):1336-43. Epub 2008 May 14.

The aetiology of the coagulopathy in the study population included; TBI (40%), warfarin use (22%), and cirrhosis (13%).
Mean prothrombin time (PT) fell from 17.0 s (+/-3.2) to 10.6s (+/-1.4) (p <0.0001).
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18957002 Crouch MA, Kasirajan V, Cahoon W, Katlaps GJ, Gunnerson KJ: Successful use and dosing of bivalirudin after temporary total artificial heart implantation: a case series. Pharmacogenet Genomics. 2009 Oct;19(10):742-50.

Additional general monitoring included activated partial thromboplastin time, prothrombin time, international normalized ratio, fibrinogen, D-dimer, platelet count, hemoglobin, hematocrit, and platelet aggregation studies.
Bivalirudin therapy was continued until successful warfarin implementation.
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19141161 Weston BW, Monahan PE: Familial deficiency of vitamin K-dependent clotting factors. Thromb Haemost. 2008 Feb;99(2):441-2.

Combined deficiency of vitamin K-dependent clotting factors II, VII, IX and X (and proteins C, S, and Z) is usually an acquired clinical problem, often resulting from liver disease, malabsorption, or warfarin overdose.
Therapy includes high oral doses of vitamin K for prophylaxis, usually resulting in partial correction of factor deficiency, and episodic use of plasma infusions or prothrombin complex concentrate.
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20337579 Benmira S, Banda ZK, Bhattacharya V: Old Versus New Anticoagulants: Focus on Pharmacology. Yakugaku Zasshi. 2009 Sep;129(9):1077-86.

Heparin, low molecular weight heparin (LMWH) and warfarin are well-established anticoagulants still in widespread use despite their well known drawbacks.
The major examples of these newer anticoagulants are the direct and indirect factor Xa inhibitors and the direct thrombin inhibitors.
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20182348 Smock KJ, Crist RA, Hansen SJ, Rodgers GM, Lehman CM: Discard tubes are not necessary when drawing samples for specialized coagulation testing. Am J Ther. 2009 May-Jun;16(3):215-23.


We performed testing for fibrinogen, D-dimer, factors VIII, IX, XI, proteins C and S, and antithrombin on 30 healthy individuals and factors II, VII, IX, X, and proteins C and S on a second group of 30 healthy individuals and 30 individuals receiving warfarin.
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18594479 Hammwohner M, Goette A: Will warfarin soon be passe? New approaches to stroke prevention in atrial fibrillation. Orthopedics. 2009 Dec;32(12 Suppl):79-84. doi: 10.3928/01477447-20091103-53.

Nevertheless, warfarin therapy has several limitations; therefore, new anticoagulants like warfarin analogs, thrombin inhibitors, or factor Xa inhibitors have been developed.
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19614967 Yoo SH, Nah HW, Jo MW, Kang DW, Kim JS, Koh JY, Kwon SU: Age and body weight adjusted warfarin initiation program for ischaemic stroke patients. Eur J Neurol. 2009 Oct;16(10):1100-5. Epub 2009 Jul 14.

METHODS: Among stroke patients who regularly visited out-patient clinics, we included patients who have continuously taken the same dose of warfarin as the prothrombin time remained at target International Nomarlized Ratio (INR).
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18257025 Savelieva I, Camm J: Update on atrial fibrillation: part I. Thromb Res. 2009 Feb;123(4):573-9. Epub 2008 May 13.

The limitations of warfarin prompted the development of new antithrombotic drugs, which include anticoagulants, such as direct oral thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban, apixaban).
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19721384 Masuda S, Oka R, Uwai K, Matsuda Y, Shiraishi T, Nakagawa Y, Shoji T, Mihara C, Takeshita M, Ozawa K: Development of clinical application for a nutritional prescription support system for total parenteral/enteral nutrition. Instr Course Lect. 2008;57:637-61.

In addition, the prothrombin time-international normalized ratio was monitored, and favorable results were obtained regarding the adjustment of the warfarin dose and nutritional management.
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18330832 Kataranovski M, Mirkov I, Vrankovic J, Kataranovski D, Subota V: Percutaneous toxicity of anticoagulant warfarin in rats. W95.

Application of 10 mug (0.05 mg/kg) or 100 mug (0.5 mg/kg) of warfarin (WF) for 3 consecutive days resulted in an increase in prothrombin time, documenting the access of warfarin to systemic circulation.
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19055640 Caldwell S, Shah N: The prothrombin time-derived international normalized ratio: great for Warfarin, fair for prognosis and bad for liver-bleeding risk. Brain Nerve. 2008 Oct;60(10):1144-58.
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18981557 Saif MW, Wasif N: Interaction between capecitabine and gemcitabine with warfarin in a patient with pancreatic cancer. Clin Lab Med. 2009 Jun;29(2):283-304.

Frequent prothrombin time and INR evaluations are suggested for anticoagulated patients receiving gemcitabine, especially when combined with capecitabine.
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19319147 Foerch C, Arai K, Van Cott EM, van Leyen K, Lo EH: Rapid reversal of anticoagulation reduces hemorrhage volume in a mouse model of warfarin-associated intracerebral hemorrhage. Anal Chem. 2009 May 1;81(9):3551-9.

Using a mouse model, we tested whether the rapid reversal of anticoagulation using human prothrombin complex concentrate (PCC) can reduce hemorrhagic blood volume.
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18670159 Ishizuka M, Tanikawa T, Tanaka KD, Heewon M, Okajima F, Sakamoto KQ, Fujita S: Pesticide resistance in wild mammals--mechanisms of anticoagulant resistance in wild rodents. Recent Pat Cardiovasc Drug Discov. 2010 Mar 26.

Warfarin is commonly used worldwide as a rodenticide.
An inadequate supply of vitamin K blocks the production of prothrombin and causes hemorrhage.
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20174595 Wu HM, Xu L, Sedmak DD, Marsh CB, Wurster MW: Personalized healthcare in clotting disorders. Acta Gastroenterol Belg. 2008 Jul-Sep;71(3):342-4.

In terms of managing thrombotic disorders, genotype-based individualized patient care emerged as early as 1994 when the association of factor V Leiden (G1691A), and later, prothrombin (G20210A), with thrombotic phenotypes were discovered.
Recently, the area of pharmacogenomics in major anti-thrombotic drugs, such as warfarin and clopidogrel, has been the principal driver for personalized therapy based on one's own individual characteristics.
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19819728 Rumph B, Bolliger D, Narang N, Molinaro RJ, Levy JH, Szlam F, Tanaka KA: In Vitro Comparative Study of Hemostatic Components in Warfarin-Treated and Fibrinogen-Deficient Plasma. J Cardiothorac Vasc Anesth. 2009 Oct 9.

Improved ROTEM variables after platelet addition are presumably caused by increased interaction among thrombin-activated platelets and fibrinogen.
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18815137 Fareed J, Jeske W, Fareed D, Clark M, Wahi R, Adiguzel C, Hoppensteadt D: Are all low molecular weight heparins equivalent in the management of venous thromboembolism?. Injury. 2008 Sep;39(9):1054-61. Epub 2008 Jul 25.


Clinical trials have demonstrated that low molecular weight heparins are at least as safe and effective as unfractionated heparin for the initial treatment of venous thromboembolism, and unfractionated heparin and warfarin for primary and secondary thromboprophylaxis.
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19415734 Maurer SH, Wilimas JA, Wang WC, Reiss UM: Heparin induced thrombocytopenia and re-thrombosis associated with warfarin and fondaparinux in a child. Blood Coagul Fibrinolysis. 2010 Mar;21(2):144-51.

Transition from bivalirudin, a direct thrombin inhibitor (DTI), to warfarin resulted in extensive re-thrombosis, and fondaparinux therapy similarly failed.
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18653820 Phillips KW, Dobesh PP, Haines ST: Considerations in using anticoagulant therapy in special patient populations. Pharmacotherapy. 2008 Nov;28(11):1413-20.

Treatment of patients with HIT should include discontinuation of heparin, temporary interruption of warfarin therapy, and initiation of a direct thrombin inhibitor.
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20345495 Pinter A, Dorian P: New Approaches to Atrial Fibrillation Management: Treat the Patient, not the ECG. Curr Opin Cardiol. 2008 Jul;23(4):315-9.

The RE-LY study showed superiority of dabigatran, an oral direct thrombin inhibitor, over warfarin in the prevention of stroke, or systemic embolism.
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20306240 Nairn TK, Giulivi A, Neurath D, Tokessy M, Sia YT, Ruel M, Wilkes PR: Urgent replacement of a mechanical mitral prosthesis in an anticoagulated patient with Bombay red blood cell phenotype. Eur J Intern Med. 2008 Mar;19(2):129-34.

We report a case of urgent repeat sternotomy for replacement of a mechanical mitral prosthesis in a patient with Bombay phenotype anticoagulated with warfarin, to emphasize the transfusion challenges in such patients.
The patient received vitamin K and prothrombin complex concentrate prior to repeat sternotomy and successful mitral prosthesis replacement.
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19330428 Wei Y, Zheng D, Xiao L, Shi B: Comparison of modes of prothrombin time reporting in patients with advanced liver disease associated with viral hepatitis. Instr Course Lect. 2009;58:781-93.

METHODS: we prospectively collected blood samples from 61 patients with advanced liver disease associated with viral hepatitis, control patients were on warfarin (n = 20).
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18573110 Gatt A, van Veen JJ, Bowyer A, Woolley AM, Cooper P, Kitchen S, Makris M: Wide variation in thrombin generation in patients with atrial fibrillation and therapeutic International Normalized Ratio is not due to inflammation. Arterioscler Thromb Vasc Biol. 2008 Mar;28(3):380-6.

Warfarin reduces this risk by at least 60%.
It is now possible to assess the intensity of anticoagulation with automated thrombin generation (TG) tests, such as the calibrated automated thrombogram (CAT).
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19052707 Angelo M, Stockner I, Wiedermann CJ: [Bleeding risk and perioperative management of patients anticoagulated with vitamin K antagnosists]. J Altern Complement Med. 2008 Jul;14(6):715-21.

Though most clinicians choose an aggressive perioperative strategy for patients with high thromboembolic risk (e.g., mechanical mitral valve replacement) by withholding warfarin perioperatively and the use of full-dose heparin, prophylactic dose heparin is given for lower risk cagegories (e.g., bileaflet aortic valve replacement and atrial fibrillation).
Patients receiving prothrombin complex concentrate have a more rapid and more complete reversal of their anticoagulation as compared with fresh frozen plasma.
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19575759 Gatt A, Riddell A, van Veen JJ, Kitchen S, Tuddenham EG, Makris M: Optimizing warfarin reversal--an ex vivo study. Wien Med Wochenschr. 2008;158(21-22):615-20.

This is commonly performed using vitamin K and, depending on the urgency, fresh frozen plasma (FFP), prothrombin complex concentrates (PCCs), or activated factor VII.
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18983306 Casimire T, Carter R, Peters S, Tweedle J, Charles KS: Establishing an oral anticoagulant monitoring service in a multiethnic developing country. Thromb Res. 2008;122 Suppl 2:S13-8.

The high incidence of underanticoagulation in Trinidad and Tobago may be due to genetically determined warfarin resistance or underdosing.
There was significant variation in geometric mean normal prothrombin time among ethnic groups: 12.7 s for Indians, 13.4 s for Africans and 13.7 s for subjects of mixed ancestry.
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20234784 Maegdefessel L, Azuma J, Tsao PS: Modern role for clopidogrel in management of atrial fibrillation and stroke reduction. Cardiovasc Ther. 2010 Mar 25.

Treatment regimens for preventing thromboembolism in AF patients range from vitamin K antagonists such as warfarin or coumadins, antiplatelet drugs like aspirin or clopidogrel, to newly developed orally available antithrombotics like the direct thrombin inhibitor dabigatran, or the Factor Xa-inhibitor rivaroxaban.
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20332192 Elliott J, Smith M: The Acute Management of Intracerebral Hemorrhage: A Clinical Review. Int J Clin Oncol. 2009 Aug;14(4):332-6. Epub 2009 Aug 25.

Treatment options for warfarin reversal include vitamin K, fresh frozen plasma, prothrombin complex concentrates, and rFVIIa.
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19572081 Greenway A, Ignjatovic V, Summerhayes R, Newall F, Burgess J, DeRosa L, Monagle P: Point-of-care monitoring of oral anticoagulation therapy in children. Blood Coagul Fibrinolysis. 2009 Jul;20(5):358-65.


The CoaguChek XS utilises a new method of electrochemical clot detection based on thrombin generation.
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19550318 Zikria JC, Ansell J: Oral anticoagulation with factor Xa and thrombin inhibitors: on the threshold of change. Curr Opin Hematol. 2009 Sep;16(5):347-56.

Within the next few years, the treatment of arterial and venous thromboembolism is again poised to undergo a major change with the introduction of new oral anticoagulants that are likely to fulfill many of the unmet needs of current warfarin therapy.
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19074090 Young G: New anticoagulants in children. Hematology Am Soc Hematol Educ Program. 2008:245-50.

The most widely used agents in children are heparin, low-molecular-weight heparins (LMWH), and warfarin.
Novel anticoagulants such as direct thrombin inhibitors and the selective factor Xa inhibitor, fondaparinux, have been approved for use in adults and have properties that suggest they may be safer and more efficacious than the standard agents; however, until recently, publications using these agents in children were limited to case reports.
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18425569 Umer Usman MH, Raza S, Raza S, Ezekowitz M: Advancement in antithrombotics for stroke prevention in atrial fibrillation. Ann Hematol. 2009 Feb;88(2):141-9. Epub 2008 Aug 21.

The current standard of therapy includes warfarin, acenocoumarol and phenprocoumon which have proven efficacy by reducing stroke by 68% against placebo.
Newer agents such as direct thrombin inhibitors, factor Xa inhibitors, factor IX inhibitors, tissue factor inhibitors and a novel vitamin K antagonist are being developed to overcome the limitations of current agents.
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20062934 Weitz JI: New oral anticoagulants in development. Cases J. 2008 Nov 2;1(1):294.

Vitamin K antagonists, such as warfarin, are administered orally, but produce a variable anticoagulant response because genetic polymorphisms, dietary vitamin K intake and multiple drug-drug interactions affect their metabolism.
These limitations have prompted the development of new oral anticoagulants that target thrombin or factor Xa and can be given in fixed doses without coagulation monitoring.
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19845677 Choppin A, Irwin I, Lach L, McDonald MG, Rettie AE, Shao L, Becker C, Palme MP, Paliard X, Bowersox S, Dennis DM, Druzgala P: Effect of tecarfarin, a novel vitamin K epoxide reductase inhibitor, on coagulation in beagle dogs. Br J Pharmacol. 2009 Nov;158(6):1536-47. Epub 2009 Oct 20.

The objective of this study was to test and compare the efficacy of tecarfarin with that of warfarin, when administered either intravenously or once a day orally, to produce stable anticoagulation in beagle dogs.
EXPERIMENTAL APPROACH: Effects on coagulation were assessed by measuring the activity levels of Factor VII and Factor X and thromboplastin-induced coagulation times, reported as prothrombin time (PT).
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18520714 Verheugt FW: Long-term anticoagulation in patients with coronary disease, and future developments. S Afr Med J. 2007 Dec;97(12):1271.

The benefit with warfarin therapy is in the range of benefit seen with clopidogrel, which is easier to administer, and there are no data assessing a possible benefit of warfarin therapy in patients taking aspirin and clopidogrel in whom the bleeding risk might be excessive.
Very recently, direct oral thrombin blockade has been developed and found to be effective in venous thromboembolism and after myocardial infarction.
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18413983 Paskauskas S, Pundzius J, Barauskas G: Venous thromboembolism and prophylaxis in cancer patients. Medicina. 2008;44(3):175-81.


Preexisting morbidity, mutations of factor V Leiden or prothrombin 20210A, type of cancer, presence of metastases, use of central venous access, surgery, anesthesia, etc., increase the risk of venous thromboembolism.
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18701850 Yasui Y, Nishiguchi T, Yamamoto A, Fujii C, Fujino M, Tsuge M, Ohno M, Azuma J, Matsumura T, Ohsato H, Anami S, Furukawa H: [A case of bleeding tendency due to warfarin in a patient treated with chemotherapy by S-1]. Gan To Kagaku Ryoho. 2008 Aug;35(8):1367-70.

Because of a bleeding tendency (non-measurable INR (international normalized ratio of prothrombin time)), WF administration was discontinued on the 11th day after S-1/GEM combined therapy was suspended.
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18574928 Teitelbaum JS, von Kummer R, Gjesdal K, Kristinsson A, Gahn G, Albers GW: Effect of ximelagatran and warfarin on stroke subtypes in atrial fibrillation. Can J Neurol Sci. 2008 May;35(2):160-5.

In the SPORTIF III and V trials, the oral direct thrombin inhibitor ximelagatran was as effective as warfarin in reducing the risk of stroke in patients with nonvalvular AF.
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19445778 Sarkees ML, Bavry AA: Acute coronary syndrome (unstable angina and non-ST elevation MI). Thromb Res. 2010 Feb 23.

CONCLUSIONS: In this systematic review we present information relating to the effectiveness and safety of the following interventions: aspirin, beta-blockers, calcium channel blockers, clopidogrel, direct thrombin inhibitors, glycoprotein IIb/IIIa inhibitors (oral or intravenous), heparin (low molecular weight, unfractionated), nitrates, routine early cardiac catheterisation and revascularisation, statins, and warfarin.
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20076850 Olsson SB, Rasmussen LH, Tveit A, Jensen E, Wessman P, Panfilov S, Wahlander K: Safety and tolerability of an immediate-release formulation of theoral direct thrombin inhibitor AZD0837 in the prevention of stroke and systemic embolism in patients with atrial fibrillation. Ann Pharmacother. 2009 Oct;43(10):1636-46. Epub 2009 Sep 8.

The present study, a multicentre, randomised, parallel-group, dose-guiding study, assessed the safety and tolerability of an immediate-release formulation of AZD0837 compared with dose-adjusted warfarin in the prevention of stroke and systemic embolic events in atrial fibrillation (AF) patients.
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18976502 Srivastava S, Solanki T: Retropharyngeal haematoma - an unusual bleeding site in an anticoagulated patient: a case report. Am J Health Syst Pharm. 2009 Jul 15;66(14):1297-303.

The patients was managed conservatively and treated with Vitamin K and Prothrombin Complex Concentrates (PCCs).
CASE PRESENTATION: We present the case of an 85-year-old Caucasian woman on warfarin, who developed a massive retropharyngeal haematoma after a fall.
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19385586 Haas SB, Barrack RL, Westrich G: Venous thromboembolic disease after total hip and knee arthroplasty. J Thromb Haemost. 2009 Jul;7(7):1123-7.

The existing pharmacologic options are parenteral heparin, fondaparinux, oral warfarin, and oral acetylsalicylic acid.
An oral form of heparin as well as direct thrombin inhibitors of factors IIa, IXa, and Xa are being developed in the hope of discovering an agent that effectively prevents thrombi formation but carries a low risk of bleeding complications.
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19915802 Wei Y, Li J, Zhang L, Zheng D, Shi B, Cong Y: Assessment of validity of INR system for patients with liver disease associated with viral hepatitis. Pharmacogenomics. 2009 Aug;10(8):1257-66.

International Normalized Ratio (INR), which standardizes prothrombin time (PT) during oral anticoagulation, has been extended to standardize PT in liver diseases and is included in all prognostic models of survival, the classification of CHILD-Pugh or Meld.
We prospectively collected blood samples from 61 patients with liver disease associated with viral hepatitis; control patients were on warfarin (n = 20).
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18467536 Ferguson JL, Hennion DR: Portal vein thrombosis: an unexpected finding in a 28-year-old male with abdominal pain. Thromb Haemost. 2008 Jun;99(6):1097-103.


Laboratory analysis revealed a heterozygous genotype for the prothrombin 20210G/A mutation, an identified risk factor for venous thrombosis.
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19717844 Connolly SJ, Ezekowitz MD, Yusuf S, Eikelboom J, Oldgren J, Parekh A, Pogue J, Reilly PA, Themeles E, Varrone J, Wang S, Alings M, Xavier D, Zhu J, Diaz R, Lewis BS, Darius H, Diener HC, Joyner CD, Wallentin L: Dabigatran versus warfarin in patients with atrial fibrillation. J Pharm Pharmacol. 2009 Apr;61(4):451-8.

Dabigatran is a new oral direct thrombin inhibitor.
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20157841 Poli D, Grifoni E, Antonucci E, Arcangeli C, Prisco D, Abbate R, Miniati M: Incidence of recurrent venous thromboembolism and of chronic thromboembolic pulmonary hypertension in patients after a first episode of pulmonary embolism. Interact Cardiovasc Thorac Surg. 2009 Apr;8(4):417-20. Epub 2009 Jan 13.

In patients who underwent OAT withdrawal D-dimer (DD), prothrombin fragment 1 + 2 (F1 + 2), and thrombophilia were evaluated one month after warfarin discontinuation.
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19737996 Blackmer AB, Oertel MD, Valgus JM: Fondaparinux and the management of heparin-induced thrombocytopenia: the journey continues. Clin Appl Thromb Hemost. 2009 May-Jun;15(3):316-26.

The use of fondaparinux as a bridging agent between direct thrombin inhibitor and warfarin therapy has been proposed.
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19966341 Schulman S, Kearon C, Kakkar AK, Mismetti P, Schellong S, Eriksson H, Baanstra D, Schnee J, Goldhaber SZ: Dabigatran versus warfarin in the treatment of acute venous thromboembolism. Vnitr Lek. 2009 Mar;55(3):272-5.

BACKGROUND: The direct oral thrombin inhibitor dabigatran has a predictable anticoagulant effect and may be an alternative therapy to warfarin for patients who have acute venous thromboembolism.
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18465493 Robins P: Anticoagulation strategies. J Thromb Haemost. 2009 Dec;7(12):2154-6. Epub 2009 Sep 9.

A number of individual presentations at this meeting dealt with the burgeoning field of anticoagulation strategies, and the fourth day (Wednesday) provided one of the most interesting symposia of the meeting, entitled 'Anticoagulation Strategies: Thrombin and Factor Xa Inhibition'.
Chair RR Wexler (DuPont Merck, PA, USA) pointed out that classical anticoagulants, such as warfarin, suffer from poor oral bioavailability, lack of selectivity and short plasma half-life.
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20101880 Balaratnam S: Prevention and treatment of thromboembolic events in medical patients and new anticoagulants. Blood Coagul Fibrinolysis. 2010 Apr;21(3):279-82.


The advent of more recent treatments such as factor Xa inhibitors and direct thrombin inhibitors may help to provide more conclusive preventative management of patients are risk of VTE.
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18464049 Au N, Rettie AE: Pharmacogenomics of 4-hydroxycoumarin anticoagulants. Br J Anaesth. 2008 Aug;101(2):250-4. Epub 2008 May 30.

Oral anticoagulants of the 4-hydroxycoumarin class, typified by warfarin, are used worldwide to treat thromboembolic disease.
However, enthusiasm for genotype-based dosing of oral anticoagulants must be balanced against the ready availability of both a simple phenotypic test (prothrombin time) and an antidote to over-anticoagulation (vitamin K).
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19222611 Khoo CW, Tay KH, Shantsila E, Lip GY: Novel oral anticoagulants. Int J Clin Pract. 2009 Apr;63(4):630-41. Epub 2009 Feb 16.

The vitamin K antagonists (VKAs), such as warfarin, have been around for the last 65 years and its efficacy as thromboprophylaxis remained largely unchallenged, at least until recently.
The novel oral anticoagulants are in 2 broad drug classes - the oral direct thrombin inhibitors and oral factor Xa inihibitors.
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20043560 Kuanprasert S, Dettrairat S, Palacajornsuk P, Kunachiwa W, Phrommintikul A: Prevalence of CYP2C9 and VKORC1 mutation in patients with valvular heart disease in northern Thailand. Per Med. 2010 Jan;7(1):65-73.

BACKGROUND: Warfarin has been widely used for the prevention and treatment of thromboembolism.
Five milliliters of whole blood was drawn from each patient for gene analysis and prothrombin time with international normalized ratio (INR) measurement.
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18501222 Dalen JE: Should patients with venous thromboembolism be screened for thrombophilia? . Br J Haematol. 2008 Sep;142(6):946-52. Epub 2008 Jun 28.


The 2 most common genetic causes of thrombophilia are the Leiden mutation of factor V and the G20210A mutation of prothrombin.
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20077167 Grobler C, Callum J, McCluskey SA: Reversal of vitamin K antagonists prior to urgent surgery. Blood Coagul Fibrinolysis. 2010 Apr;21(3):242-4.

PURPOSE: The purpose of this article is to review the effective options for the reversal of vitamin K antagonists (warfarin and it coumarin analogues) and to help identify the option best suited for the patient requiring urgent surgery.
PRINCIPAL FINDINGS: Vitamin K antagonists, the mainstay in long-term anticoagulation therapy, can be reversed with the administration of vitamin K, frozen plasma (FP), recombinant factor VIIa (rFVIIa), or the recently approved four-factor prothrombin complex concentrate (PCC), Octaplex (R).
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20175844 Kawakami T: New algorithm (KAWAKAMI algorithm) to diagnose primary cutaneous vasculitis. Scand J Clin Lab Invest. 2008;68(5):427-30.

In cutaneous polyarteritis nodosa, warfarin or clopidogrel therapies should be administrated, and in cases that have associated active inflammatory lesions, corticosteroids or mizoribine (mycophenolate mofetil) therapy should be added.
Finally, the presence of anti-phosphatidylserine-prothrombin complex antibodies and/or lupus anticoagulant and histopathological necrotizing vasculitis in the upper to middle dermis (leukocytoclastic vasculitis) indicates cutaneous leukocytoclastic angiitis, whereas if necrotizing vasculitis exists in the lower dermis and/or is associated with the subcutaneous fat, cutaneous polyarteritis nodosa is indicated.
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18788615 Chen HY, Ding QL, Zhang LW, Xu GQ, Dai J, Wang XF, Xi XD, Wang HL: [The application of thrombin generation tests to warfarin anticoagulation monitoring]. J Am Acad Dermatol. 2008 Mar;58(3):512-5.
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19423152 Wieloch M, Hillarp A, Strandberg K, Nilsson C, Svensson PJ: Comparison and evaluation of a Point-of-care device (CoaguChek XS) to Owren-type prothrombin time assay for monitoring of oral anticoagulant therapy with warfarin. Thromb Res. 2009 Jul;124(3):344-8. Epub 2009 May 6.
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18925967 Schulman S, Elbazi R, Zondag M, O'Donnell M: Clinical factors influencing normalization of prothrombin time after stopping warfarin: a retrospective cohort study. Thromb J. 2008 Oct 16;6:15.
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18515818 Chelly JE, Szczodry DM, Neumann KJ: International normalized ratio and prothrombin time values before the removal of a lumbar plexus catheter in patients receiving warfarin after total hip replacement. Expert Opin Pharmacother. 2008 Oct;9(14):2509-17.
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18249309 Habib G, Nashashibi M, Khateeb A, Goichman S, Kogan A: Excessive prolongation of prothrombin time among patients treated with warfarin and admitted to the emergency room. Ann Intern Med. 2009 Aug 18;151(4):270-3
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19949893 Cugno M, Marzano AV, Asero R, Tedeschi A: Activation of blood coagulation in chronic urticaria: pathophysiological and clinical implications. Lancet Neurol. 2010 Mar;9(3):273-84.

In CU, several investigators have demonstrated the activation of coagulation that is due to the involvement of eosinophils and a tissue factor pathway with generation of thrombin potentially contributing to an increased vascular permeability.
Preliminary data indicate that anticoagulant treatment with heparin and warfarin may be effective in reducing the symptoms of this disorder.
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18946305 Levy JH, Tanaka KA, Dietrich W: Perioperative hemostatic management of patients treated with vitamin K antagonists. Pathology. 2008 Apr;40(3):277-87.

Before elective surgery, anticoagulation reversal may be undertaken over several days by discontinuing warfarin or vitamin K treatment, but rapid correction is required in an emergency.
European and American guidelines recommend prothrombin complex concentrates (PCCs) for anticoagulation reversal in patients with life-threatening bleeding and an increased international normalized ratio.
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18385150 Lazo-Langner A, Villa-Marquez R, Hernandez-Hernandez D, Rojas-Maya S, Piedras J: Intrahospital correlation of the international normalized ratio. J Thromb Thrombolysis. 2010 Jan;29(1):81-6. Epub 2009 Mar 28.

These results are clearly inadequate for clinical use because such a variation would most probably induce the clinician to make a change in warfarin dose.
Monitoring of oral anticoagulant therapy (OAT) is usually accomplished by measuring prothrombin time and the international normalized ratio (INR).
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20131309 Castellone DD, Van Cott EM: Laboratory monitoring of new anticoagulants. J Eur Acad Dermatol Venereol. 2010 Mar 13.

There are now a variety of new anticoagulant drugs in clinical use including several direct thrombin inhibitors (DTIs), such as argatroban, bivalirudin, and hirudin, as well as a Factor Xa inhibitor, fondaparinux.
In addition, laboratory testing can assist with transitioning patients from DTI to warfarin therapy.
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20203456 Osinbowale O, Ali L, Chi YW: Venous thromboembolism: a clinical review. Coll Antropol. 2008 Mar;32(1):103-7.

Alternative oral anticoagulants, such as direct thrombin inhibitors and factor Xa inhibitors, are subjects of active research in alternative agents for oral anticoagulation, and have been recently approved for prophylaxis in Canada and the European Union.
Warfarin is the only oral anticoagulant approved by the US Food and Drug Administration.
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19496921 Ryan F, Byrne S, O'Shea S: Randomized controlled trial of supervised patient self-testing of warfarin therapy using an internet-based expert system. Clin Appl Thromb Hemost. 2008 Oct;14(4):385-92.

BACKGROUND: Increased frequency of prothrombin time testing, facilitated by patient self-testing (PST) of the International Normalized Ratio (INR) can improve the clinical outcomes of oral anticoagulation therapy (OAT).
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19181420 Warren O, Simon B: Massive, fatal, intracardiac thrombosis associated with prothrombin complex concentrate. Ann Emerg Med. 2009 Jun;53(6):758-61. Epub 2009 Feb 1.

We report a patient receiving warfarin who presented to the emergency department with an international normalization ratio greater than 12.8 in cardiac tamponade and received prothrombin complex concentrate for rapid reversal of anticoagulation.
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19920886 Attia FM, Mikhailidis DP, Reffat SA: Prothrombin Gene G20210A Mutation in Acute Deep Venous Thrombosis Patients with Poor Response to Warfarin Therapy. Open Cardiovasc Med J. 2009 Oct 21;3:147-51.
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20181379 Salmela B, Joutsi-Korhonen L, Saarela E, Lassila R: Comparison of monitoring methods for lepirudin: Impact of warfarin and lupus anticoagulant. J Dermatol. 2010 Feb;37(2):113-24.

We compared APTT with thrombin-specific methods, also in the presence of warfarin and lupus anticoagulant (LA).
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18549908 Pabinger-Fasching I: Warfarin-reversal: results of a phase III study with pasteurised, nanofiltrated prothrombin complex concentrate. Thromb Res. 2008;122 Suppl 2:S19-22.
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19150310 Kamath PS, Kim WR: The international normalized ratio of prothrombin time in the model for end-stage liver disease score: a reliable measure. 810.e1-2.

Virtually every study that has looked at the MELD score as a predictor of survival has demonstrated that the MELD score using the INR with international sensitivity index calibrated for patients on warfarin has a 'c' statistic of approximately 0.8, indicating excellent discrimination.
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19516255 Wajima T, Isbister GK, Duffull SB: A comprehensive model for the humoral coagulation network in humans. Thromb Haemost. 2010 Jan;103(1):62-70. Epub 2009 Oct 26.

The model accurately describes the time courses of coagulation factors following in vivo activation as well as in vitro blood coagulation tests of prothrombin time (PT, often reported as international normalized ratio (INR)) and activated partial thromboplastin time (aPTT).
The model predicts the concentration-time and time-effect profiles of warfarin, heparins, and vitamin K in humans.
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18406993 Nutescu EA, Shapiro NL, Chevalier A: New anticoagulant agents: direct thrombin inhibitors. . Clin Nephrol. 2010 Apr;73(4):326-30.

In recent years, much emphasis has been placed on the development of direct thrombin inhibitors (DTIs) that offer benefits over agents like heparin and warfarin including the inhibition of both circulating and clot-bound thrombin; a more predictable anticoagulant response, because they do not bind to plasma proteins and are not neutralized by platelet factor 4; lack of required cofactors, such as antithrombin or heparin cofactor II; inhibiting thrombin-induced platelet aggregation; and absence of induction of immune-mediated thrombocytopenia.
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19365276 De Caterina R, Kristensen SD, Renda G: New anticoagulants for atrial fibrillation. Clin Pharmacol Ther. 2009 Sep;86(3):290-8. Epub 2009 Jun 10.

Although warfarin and other vitamin K antagonists have clearly the greatest efficacy among treatments commonly available in preventing stroke in atrial fibrillation, their use is associated with a substantial risk of major bleedings and are unpractical and difficult to use because of their narrow therapeutic window, their interaction with drugs and foods, and the need of frequent coagulation monitoring.
These drugs fall in different pharmacological categories of oral direct thrombin inhibitors, parenteral long-lived indirect factor Xa inhibitors, and oral direct factor Xa inhibitors.
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19882303 Makris M, van Veen JJ, Maclean R: Warfarin anticoagulation reversal: management of the asymptomatic and bleeding patient. J Thromb Thrombolysis. 2010 Feb;29(2):171-81.

In the presence of major bleeding, treatment with intravenous vitamin K and prothrombin complex concentrate is the most effective therapy.
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20179722 Verheugt FW: Novel oral anticoagulants to prevent stroke in atrial fibrillation. Nat Rev Cardiol. 2010 Mar;7(3):149-54.

In one of these trials an oral thrombin blocker has so far shown superiority to warfarin in efficacy and safety.
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20171423 Vaz-da-Silva M, Almeida L, Falcao A, Soares E, Maia J, Nunes T, Soares-da-Silva P: Effect of eslicarbazepine acetate on the steady-state pharmacokinetics and pharmacodynamics of warfarin in healthy subjects during a three-stage, open-label, multiple-dose, single-period study. Clin Ther. 2010 Jan;32(1):179-92.

METHODS: Subjects received ESL 1200 mg once daily for 8 days concomitantly with racemic warfarin, the dose of which had been individually optimized to a stable prothrombin international normalized ratio (INR) of 1.3 to 1.8 during a previous run-in phase (up to 21 days).
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20144498 Hong CH, Napenas JJ, Brennan MT, Furney SL, Lockhart PB: Frequency of Bleeding Following Invasive Dental Procedures in Patients on Low-Molecular-Weight Heparin Therapy. Thromb Res. 2009 Dec 9.

One patient had persistent bleeding after extraction of 4 teeth (international normalized ratio, 1.6), which was successfully controlled with topical thrombin, administration of vitamin K and fresh frozen plasma, and discontinuation of enoxaparin and warfarin.
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18471452 Finkelstein A, Bazan S, Halkin A, Herz I, George J, Miller HI, Keren G, Banai S: Treatment of post-catheterization femoral artery pseudo-aneurysm with para-aneurysmal saline injection. Hematology Am Soc Hematol Educ Program. 2008:266-70.

Ultrasound-based techniques (e.g., mechanical compression, thrombin injection) and open surgical intervention are frequently used in the management of pseudoaneurysm.
In none of the patients was concomitant antithrombotic therapy (aspirin [n = 63], clopidogrel [n = 45], unfractionated or low-molecular-weight heparin [n = 23], and warfarin [n = 5]) discontinued during the closure attempt.
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19883336 Cugno M, Tedeschi A, Asero R, Meroni PL, Marzano AV: Skin autoimmunity and blood coagulation. J Thromb Haemost. 2008 May;6(5):820-9. Epub 2008 Feb 25.

Several investigators demonstrated the activation of coagulation in CU through the involvement of eosinophils, of TF pathway with thrombin generation and increased vascular permeability.
Preliminary data indicate that anticoagulant treatment with heparin and warfarin may be effective in reducing the symptoms of this disorder.
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18956996 Baetz BE, Spinler SA: Dabigatran etexilate: an oral direct thrombin inhibitor for prophylaxis and treatment of thromboembolic diseases. Am J Cardiol. 2008 May 15;101(10):1418-22. Epub 2008 Mar 17.

As the only oral anticoagulation option available in the United States, warfarin use remains widespread.
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18586684 Kupeli E, Cengiz C, Cila A, Karnak D: Hyperhomocysteinemia due to pernicious anemia leading to pulmonary thromboembolism in a heterozygous mutation carrier. Intern Emerg Med. 2009 Dec 1.

Screening for thrombophilic states was normal except for heterozygous mutations of both prothrombin and methylene tetrahydrofolate reductase (MTHFR 677) genes.
After the diagnoses were established, enoxaparin followed by warfarin was started in addition to oral vitamin B12, pyridoxine, thiamine, folic acid, and ferroglycine sulfate supplementation.
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18685448 White R, Rushbrook J, McGoldrick J: The dangers of prothrombin complex concentrate administration after heart surgery. J Interv Card Electrophysiol. 2008 Aug;22(2):129-37. Epub 2008 Apr 17.

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20135071 Ufer M: Comparative efficacy and safety of the novel oral anticoagulants dabigatran, rivaroxaban and apixaban in preclinical and clinical development. J Cereb Blood Flow Metab. 2009 May;29(5):1015-21. Epub 2009 Mar 25.

Therapeutic oral anticoagulation is still commonly achieved by administration of warfarin or other vitamin K antagonists that are associated with an untoward pharmacokinetic / pharmacodynamic (PK/PD) profile leading to a high incidence of bleeding complications or therapeutic failure.
Of these, the thrombin inhibitor dabigatran and factor Xa inhibitor rivaroxaban have recently been licensed for thromboprophylaxis after orthopaedic surgery mainly in Europe.
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18619081 Dresang LT, Fontaine P, Leeman L, King VJ: Venous thromboembolism during pregnancy. Anesthesiology. 2008 Nov;109(5):918-26.

Warfarin is contraindicated during pregnancy, but is safe to use postpartum and is compatible with breastfeeding.
Factor V Leiden and prothrombin G20210A mutation are the most common inherited thrombophilias, and antiphospholipid antibody syndrome is the most important acquired defect.
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18280355 Davis MD, Wysokinski WE: Ulcerations caused by livedoid vasculopathy associated with a prothrombotic state: Response to warfarin. J Am Board Fam Med. 2008 May-Jun;21(3):237-43.

She was a heterozygous carrier of factor V Leiden and prothrombin gene mutations and was receiving hormone replacement therapy.
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19074093 Francis CW: New issues in oral anticoagulants. Clin Appl Thromb Hemost. 2008 Jul;14(3):365-8.

Polymorphisms in CYP2C9, a critical cytochrome P-450 enzyme in the metabolism of warfarin, alters its clearance and affects dosing.
Dabigatran is an oral direct thrombin inhibitor that has been compared with enoxaparin for prevention of VTE following hip or knee replacement.
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18474393 Brodin E, Seljeflot I, Arnesen H, Hurlen M, Appelbom H, Hansen JB: Endogenous thrombin potential (ETP) in plasma from patients with AMI during antithrombotic treatment. J Intern Med. 2008 Jul;264(1):50-61. Epub 2008 Feb 4.

OBJECTIVES: The aims were to investigate the effect of warfarin and platelet inhibition on thrombin generation, assessed by the endogenous thrombin potential (ETP), and study the relation between coagulation parameters and ETP in patients with AMI.
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19210325 Holland L, Warkentin TE, Refaai M, Crowther MA, Johnston MA, Sarode R: Suboptimal effect of a three-factor prothrombin complex concentrate (Profilnine-SD) in correcting supratherapeutic international normalized ratio due to warfarin overdose. Transfusion. 2009 Jun;49(6):1171-7. Epub 2009 Feb 6.
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20004955 Szlam F, Luan D, Bolliger D, Szlam AD, Levy JH, Varner JD, Tanaka KA: Anti-factor IXa Aptamer reduces propagation of thrombin generation in plasma anticoagulated with warfarin. Am J Health Syst Pharm. 2009 Dec 1;66(23):2123-5.
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20045627 Costa IM, Serralheiro AI, Rodrigues M, Alves G, Falcao AC: Usefulness of factor II and factor X as therapeutic markers in patients under chronic warfarin therapy. Biomed Pharmacother. 2010 Feb;64(2):130-2. Epub 2009 Dec 16.

Although prothrombin time (usually expressed as International normalized ratio [INR]) is the most common warfarin response marker, clotting factors (namely factors II and X) are also indicated as alternative anticoagulant effect markers.
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18756910 Samardzija M, Topic E, Stefanovic M, Zibar L, Samardzija G, Balen S, Vcev A, Domanovic D, Mirat J, Barbic J: Association of CYP2C9 gene polymorphism with bleeding as a complication of warfarin therapy. Blood Coagul Fibrinolysis. 2009 Sep 7.

Those with allele *3 had significantly lower maintenance warfarin dose (p=0.005) and higher prothrombin time (PT) at induction (p=0.034).
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18609070 Enstrom C, Osman A, Lindahl TL: A genotyping method for VKORC1 1173C> T by Pyrosequencing ((R)) technology. Drug Saf. 2009;32(3):203-18. doi: 10.2165/00002018-200932030-00003.

The SNP rs9934438 in intron 1 of VKORC1 (c.173+1000C> T or 1173C> T) discriminating the VKORC1*2 haplotype is associated with low warfarin dose requirement and unstable prothrombin time - international normalized ratio.
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19020747 Murata K, Sakamoto A: Impairment of clathrin-mediated endocytosis via cytoskeletal change by epithelial to fibroblastoid conversion in HepG2 cells: a possible mechanism of des-gamma-carboxy prothrombin production in hepatocellular carcinoma. Autoimmunity. 2010 Mar;43(2):189-94.

For example, vitamin K-deficiency or ingestion of a vitamin K antagonist (warfarin) also leads to DCP production.
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19811220 Flores-Nascimento MC, Beltrame MP, De Paula EV, Montalvao SL, Pereira FG, Orsi FL, Lorand-Metze I, Annichino-Bizzacchi JM: Microparticles in deep venous thrombosis, antiphospholipid syndrome and Factor V Leiden. Crit Care. 2008;12(4):R105. Epub 2008 Aug 15.

This study compared the number, cellular origin and procoagulant activity of MPs on DVT patients in different clinical situations: at diagnosis (n = 9, 5F/4M; mean age = 41.11), 1-3 years after warfarin withdrawal (n = 10, 7F/3M; mean age = 32.90), associated to antiphospholipid syndrome (APS; n = 11, 9F/2M; mean age = 33.82), or asymptomatic carriers of Factor V Leiden (FVL; n = 7, 7F/0M; mean age = 34.00) vs healthy controls (CTR).
The plasmatic procoagulant activity was investigated by prothrombin fragment 1 + 2 (F1 + 2) determination.
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19417631 Christensen TD, Jensen C, Larsen TB, Christiansen K, Sorensen B: Thrombin generation and coagulation factor activities: evaluation and comparison with the international normalized ratio. N Engl J Med. 2009 Sep 17;361(12):1139-51. Epub 2009 Aug 30.

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18929235 Lee LV: Anticoagulants in coronary artery disease. . 2280-1.

Anticoagulant therapy for acute coronary syndromes is becoming more complex as newer agents are added to unfractionated heparin and warfarin.
The anticoagulants used in current clinical practice are low molecular weight heparins, direct thrombin inhibitors, and heparinoids.
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18485088 Anstee QM, Goldin RD, Wright M, Martinelli A, Cox R, Thursz MR: Coagulation status modulates murine hepatic fibrogenesis: implications for the development of novel therapies. Clin Appl Thromb Hemost. 2009 Mar-Apr;15(2):220-4. Epub 2008 Apr 1.

It is likely that thrombin signaling through the proteinase-activated receptor 1 (PAR (1)) receptor expressed on hepatic stellate cells is responsible for this relationship.
Anticoagulation with warfarin significantly reduced fibrosis progression in wild-type mice but was less effective against the profibrotic FV Leiden mutation.
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18278197 De Paulis S, Rossi E, Zamparelli R, Scapigliati A, Corrado M, De Stefano V: Early postoperative obstructive prosthetic mitral valve thrombosis in a patient double heterozygous for factor V Leiden and prothrombin G20210A mutation. Platelets. 2009 Sep;20(6):367-75.

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19141491 Imagawa H, Ryugo M, Shikata F, Nakata T, Nagashima M, Kawachi K: Coagulant activity during one year after bioprosthetic aortic valve replacement. Ther Drug Monit. 2008 Jun;30(3):276-81.

Anticoagulant therapy with warfarin is recommended in the early postoperative period after bioprosthetic aortic valve replacement (bAVR).
We evaluated postoperative coagulant activity data including prothrombin time-international normalized ratio (PT-INR) and thrombin-antithrombin III complex (TAT), measured every month in 21 bAVR patients during the 1st postoperative year.
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19967567 Bershad EM, Suarez JI: Prothrombin Complex Concentrates for Oral Anticoagulant Therapy-Related Intracranial Hemorrhage: A Review of the Literature. Postgrad Med. 2010 Mar;122(2):54-65.

We aim to review the literature regarding the use of prothrombin complex concentrates in patients with warfarin-related intracranial hemorrhage.
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19300085 Aiyagari V, Testai FD: Correction of coagulopathy in warfarin associated cerebral hemorrhage. . Pharmacotherapy. 2008 Nov;28(11):1354-73.

RECENT FINDINGS: Agents such as prothrombin complex conjugates and recombinant activated factor VII are being increasingly used to emergently correct warfarin-associated coagulopathy.
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18307563 Evans SJ, Biss TT, Wells RH, Hanley JP: Emergency warfarin reversal with prothrombin complex concentrates: UK wide study. Br J Haematol. 2008 Apr;141(2):268-9. Epub 2008 Feb 23.
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18413687 Carroll DN, Carroll DG: Interactions between warfarin and three commonly prescribed fluoroquinolones. Am Surg. 2008 Sep;74(9):858-61.

Reports were selected based on the use of typical treatment courses of fluoroquinolones during concomitant warfarin therapy and the reporting of prothrombin time (PT) or international normalized ratio (INR).
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19817161 Sjalander A, Berntorp E, Svensson PJ: [Prothrombin complex concentrate good in warfarin induced hemorrhage. Lakartidningen. 2009 Sep 9-15;106(37):2278
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19998810 Cortez-Dias N, Correia MJ, Coutinho A, Fernandes C, Diogo AN, Lopes MG: Pharmacogenetics and anticoagulant therapy: two cases of genetically determined response to warfarin. Rev Port Cardiol. 2009 Sep;28(9):995-1004.

In the second case, a 76-year-old man with permanent atrial fibrillation developed excessive prolongation of prothrombin time after being treated with 5 mg/day warfarin for 5 days.
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19028773 Lazo-Langner A, Rodger MA, Wells PS: Lessons from ximelagatran: issues for future studies evaluating new oral direct thrombin inhibitors for venous thromboembolism prophylaxis in orthopedic surgery. J Thromb Thrombolysis. 2009 Nov 14.

Medline, EMBASE, the Cochrane Library, and grey literature were screened for randomized trials comparing ximelagatran with warfarin or low-molecular-weight heparin for thromboprophylaxis in total hip or knee replacement.
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19054792 Taimeh Z, Weksler B: Review: recent advances in argatroban-warfarin transition in patients with heparin-induced thrombocytopenia. Clin Appl Thromb Hemost. 2010 Feb;16(1):5-12. Epub 2008 Dec 2.

Direct thrombin inhibitors are now standard therapy for the prevention of thrombosis in heparin-induced thrombocytopenia.
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18302088 Linkins LA, Warkentin TE: The approach to heparin-induced thrombocytopenia. . Anesth Analg. 2010 Mar 23.

HIT is an intense hypercoagulability state (increased thrombin generation in vivo) that is complicated more often by venous thromboembolism (deep vein thrombosis, pulmonary embolism) than by arterial thrombosis.
Coumarins (e.g., warfarin) are therefore contraindicated during the acute (thrombocytopenic) phase of HIT.
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19376304 Ezekowitz MD, Connolly S, Parekh A, Reilly PA, Varrone J, Wang S, Oldgren J, Themeles E, Wallentin L, Yusuf S: Rationale and design of RE-LY: randomized evaluation of long-term anticoagulant therapy, warfarin, compared with dabigatran. Am Fam Physician. 2008 Jun 15;77(12):1709-16.

Dabigatran etexilate is a prodrug that is rapidly converted to the active direct thrombin inhibitor dabigatran.
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19397481 Lippi G, Franchini M, Favaloro EJ: Pharmacogenetics of vitamin K antagonists: useful or hype? . Cardiol Clin. 2008 Nov;26(4):615-28.

However, the ongoing development of new anticoagulant drugs targeting thrombin and factor X will introduce a paradigm shift in long-term anticoagulation therapy, so that consideration could be given to demise pharmacogenetics testing for VKAs.
Genetic testing has been proposed as a useful tool for allowing prediction of the dose response during initial anticoagulation therapy, to assess variability in dose maintenance and to identify warfarin 'resistance'.
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19752778 Grandemange A, Kohn MH, Lasseur R, Longin-Sauvageon C, Berny P, Benoit E: Consequences of the Y139F Vkorc1 mutation on resistance to AVKs: in-vivo investigation in a 7th generation of congenic Y139F strain of rats. Thromb Haemost. 2009 Feb;101(2):405-7.

OBJECTIVES: In humans, warfarin is used as an anticoagulant to reduce the risk of thromboembolic clinical events.
RESULTS AND CONCLUSION: In this manuscript we report the prothrombin times measured in the F7 generation after exposure to chlorophacinone, bromadiolone, difenacoum and difethialone.
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18399613 Pellegrini VD Jr, Sharrock NE, Paiement GD, Morris R, Warwick DJ: Venous thromboembolic disease after total hip and knee arthroplasty: current perspectives in a regulated environment. Int J Lab Hematol. 2008 Dec;30(6):531-5.

Prevention of venographic thrombosis is most efficacious by administering fractionated heparin followed by warfarin; warfarin (international normalized ratio 2.0) appears to have a greater safety margin than fractionated heparin based on clinically meaningful bleeding events.
Oral thrombin inhibitors hold promise, but instances of liver toxicity have precluded approval in North America to date.
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18576904 Zimmerman JJ, Raible DG, Harper DM, Matschke K, Speth JL: Evaluation of a potential tigecycline-warfarin drug interaction. . Curr Opin Crit Care. 2009 Apr;15(2):87-92.

Pharmacodynamic analyses were based on anticoagulant parameters derived from international normalized ratios of prothrombin times.
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19067473 Vakily M, Lee RD, Wu J, Gunawardhana L, Mulford D: Drug interaction studies with dexlansoprazole modified release (TAK-390MR), a proton pump inhibitor with a dual delayed-release formulation: results of four randomized, double-blind, crossover, placebo-controlled, single-centre studies. Am J Perinatol. 2009 Sep;26(8):597-600. Epub 2009 Apr 29.

The potential for a pharmacodynamic interaction was also assessed for warfarin using prothrombin time, measured as the international normalized ratio.
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19298691 Chan E, Hegde A, Chen X: Effect of rutin on warfarin anticoagulation and pharmacokinetics of warfarin enantiomers in rats. Clin Liver Dis. 2009 Feb;13(1):63-6.

RESULTS: Rutin reduced the anticoagulant effect of racemic warfarin, evident as a 31% reduction in the area under the prothrombin complex activty-time curve (P < 0.05).
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19190829 Rosenzweig N, Strauss T, Rubinstein M, Paret G, Kenet G: Activated protein C concentrate treatment for skin necrosis under warfarin treatment in severe genetic protein C deficiency combined with prothrombin mutation and factor V Leiden. Haemophilia. 2008 Nov;14(6):1209-13.
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19139370 Lee SH, Ryu WS, Roh JK: Cerebral microbleeds are a risk factor for warfarin-related intracerebral hemorrhage. Neurology. 2009 Jan 13;72(2):171-6.

Conditional logistic regression analysis showed that increased prothrombin time and the presence of microbleeds were independently related to the incidence of warfarin-related ICH (microbleeds: adjusted OR, 83.12).
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19342840 Marti-Fabregas J, Mateo J: Old and new anticoagulant agents for the prevention and treatment of patients with ischemic stroke. Int J Oncol. 2008 Dec;33(6):1149-55.

Although ximelagatran was withdrawn early because of liver toxicity, it provided convincing evidence that new oral anticoagulants have the potential to replace warfarin.
The new anticoagulants that are being investigated target factor Xa or thrombin.
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18550588 Sipahi T, Karademir S, Kuybulu A, Akar N: Diffuse cerebral infarct associated with factor V Leiden and prothrombin 20210A mutations in a patient with tetralogy of Fallot. J Med Assoc Thai. 2009 Dec;92(12):1597-601.

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18315548 Wong PC, Crain EJ, Xin B, Wexler RR, Lam PY, Pinto DJ, Luettgen JM, Knabb RM: Apixaban, an oral, direct and highly selective factor Xa inhibitor: in vitro, antithrombotic and antihemostatic studies. Am J Hematol. 2010 Mar;85(3):185-7.

It exhibited species difference in FXa inhibition [FXa K (i) (nm): 0.16, rabbit; 1.3, rat; 1.7, dog] and anticoagulation [EC (2x) (microm, concentration required to double the prothrombin time): 3.6, human; 2.3, rabbit; 7.9, rat; 6.7, dog].
In vivo, the values for antithrombotic ED (50) (dose that reduced thrombus weight or increased blood flow by 50% of the control) in AVST, VT and ECAT and the values for BT ED (3x) (dose that increased BT by 3-fold) were 0.27 +/- 0.03, 0.11 +/- 0.03, 0.07 +/- 0.02 and > 3 mg kg (-1) h (-1) i.v. for apixaban, 0.05 +/- 0.01, 0.05 +/- 0.01, 0.27 +/- 0.08 and > 3 mg kg (-1) h (-1) i.v. for the indirect FXa inhibitor fondaparinux, and 0.53 +/- 0.04, 0.27 +/- 0.01, 0.08 +/- 0.01 and 0.70 +/- 0.07 mg kg (-1) day (-1) p.o. for the oral anticoagulant warfarin, respectively.
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18296593 Gross PL, Weitz JI: New anticoagulants for treatment of venous thromboembolism. . v-vi.

Extended treatment usually involves the administration of vitamin K antagonists, such as warfarin.
These agents include idraparinux, a long-acting synthetic pentasaccharide that is given subcutaneously on a once-weekly basis, and new oral anticoagulants that target thrombin or factor Xa.
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18665922 Smith SA, Morrissey JH: Polyphosphate as a general procoagulant agent. Pharmacotherapy. 2008 Jul;28(7):895-905.

Polyphosphate also significantly shortened the clotting time of normal plasmas containing a variety of anticoagulant drugs, including unfractionated heparin, enoxaparin (a low molecular weight heparin), argatroban (a direct thrombin inhibitor) and rivaroxaban (a direct FXa inhibitor).
Polyphosphate also shortened the clotting times of plasmas from warfarin patients.
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18975602 Kitagawa Y, Ohkuma H, Tokuoka K: [Ischemic stroke with antiphospholipid antibody] . Thromb Haemost. 2009 Jul;102(1):159-65.


Recently, phosphatidylserine dependent anti-prothrombin antibody has been suggested to be closely related to LA. aPL is an independent risk factor for a first-ever ischemic stroke, especially in young female patients.
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19185786 Drouet L: [Rivaroxaban: mode of action] . Ann Fr Anesth Reanim. 2008 Dec;27 Suppl 3:S9-15.


The advantage for the direct anti-Xa inhibitors such as rivaroxaban is that the prothrombin time, a routine test is sensitive and provides a prolonged response that is proportional to the plasma concentration within a wide range of concentrations.
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19705244 Arai S, Mitsufuji H, Nishii Y, Onoda S, Ryuge S, Wada M, Katono K, Iwasaki M, Takakura A, Otani S, Yamamoto M, Yanaihara T, Yokoba M, Kubota M, Katagiri M, Fukui T, Kobayashi H, Yanase N, Hataishi R, Masuda N: Effect of gefitinib on warfarin antithrombotic activity. Am J Med. 2008 Jun;121(6):458-63.

We analyzed the prevalence of the concomitant use of warfarin and gefitinib, and the incidence of prothrombin time-international normalized ratio (PT-INR) alterations or adverse interactions in concomitant users of warfarin and gefitinib.
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18294668 Maeda M, Murakami M, Takegami T, Ota T: Promotion or suppression of experimental metastasis of B16 melanoma cells after oral administration of lapachol. J Thromb Haemost. 2009 Aug;7(8):1284-90. Epub 2009 May 30.

Six hours after oral administration of lapachol or warfarin, the protein C level was reduced maximally, without elongation of prothrombin time.
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19682336 Dunbar NM, Chandler WL: Thrombin generation in trauma patients. Acta Clin Belg. 2009 Nov-Dec;64(6):547-52.

STUDY DESIGN AND METHODS: Thrombin generation assays were used to evaluate plasma hemostasis in 42 trauma patients, 25 normal subjects, and 45 patients on warfarin and in laboratory-prepared factor reduced plasma.
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18989636 Schwartz JI, Dunbar S, Yuan J, Li S, Gipson A, Rosko K, Johnson-Levonas AO, Lasseter KC, Addy C, Stoch AS, Wagner JA: Influence of taranabant, a cannabinoid-1 receptor inverse agonist, on pharmacokinetics and pharmacodynamics of warfarin. Cardiol Clin. 2008 May;26(2):169-87

Blood samples were collected predose and up to 168 hours postdose for assay of R (+)-and S (-)-warfarin and prothrombin time/international normalized ratio (PT/INR).
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19404899 Masamoto H, Uehara H, Mekaru K, Uezato T, Sakumoto K, Aoki Y: Warfarin-associated fetal intracranial hemorrhage in woman with mitral valve replacements: a case report. Drug Metab Rev. 2008;40(2):355-75.

Following this, she was prescribed oral warfarin again (3.5 mg per day), with a strict control of prothrombin time/international normalized ratio (PT/INR).
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18521514 Bauman ME, Black KL, Massicotte MP, Bauman ML, Kuhle S, Howlett-Clyne S, Cembrowski GS, Bajzar L: Accuracy of the CoaguChek XS for point-of-care international normalized ratio (INR) measurement in children requiring warfarin. JOP. 2008 Nov 3;9(6):739-43.

POC INR meter validations were performed on plasma samples from two time points from 62 children receiving warfarin by drawing a venous blood sample for laboratory prothrombin (PT)-INR measurements and simultaneous INR determinations using the POC-INR meter.
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19574605 Cooper T, Taber D, Mazur J: Implementation of a collaborative drug therapy management service for inpatients receiving direct thrombin inhibitors. Thromb Res. 2009 Jun;124(2):161-6. Epub 2009 Jan 9.

The DTI order form consisted of five main sections: practice points pertaining to the clinical diagnosis of heparin-induced thrombocytopenia (HIT), initiation of DTIs, nurse- and pharmacist-driven instructions for the monitoring of DTI therapy, information to safely transition a patient from a DTI to warfarin, and a scoring system for determining the probability of HIT.
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19436123 Suda K, Kudo Y, Higaki T, Nomura Y, Miura M, Matsumura M, Ayusawa M, Ogawa S, Matsuishi T: Multicenter and retrospective case study of warfarin and aspirin combination therapy in patients with giant coronary aneurysms caused by Kawasaki disease. Toxicol Appl Pharmacol. 2008 Jun 1;229(2):232-8. Epub 2008 Jan 26.

Target international normalized ratio of prothrombin time ranged from 1.5 to > or =2.5.
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19228605 Farmer-Boatwright MK, Roubey RA: Venous thrombosis in the antiphospholipid syndrome. . Arterioscler Thromb Vasc Biol. 2009 Mar;29(3):321-5.

The optimal intensity of warfarin therapy is an ongoing issue, but most clinicians currently favor a target INR in the 2.0 to 3.0 range.
The most common antigens are beta2-glycoprotein I and prothrombin.
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20337814 Di Giacomo TB, Hussein TP, Souza DG, Criado PR: Frequency of thrombophilia determinant factors in patients with livedoid vasculopathy and treatment with anticoagulant drugs - a prospective study. Zhonghua Xue Ye Xue Za Zhi. 2008 Mar;29(3):168-70.

Methods Thirty-four LV patients were tested for prothrombin time, activated partial thromboplastin time, antithrombin activity, protein C and S activity, anticardiolipin antibodies, lupus anticoagulant, prothrombin gene mutation, factor V Leiden mutation, methylenetetrahydrofolate reductase mutation, plasma homocysteine and fibrinogen.
Thirteen of these patients were treated with anticoagulant drugs (either warfarin or heparin).
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18814828 Usman MH, Notaro LA, Patel H, Ezekowitz MD: New developments in anticoagulation for atrial fibrillation. J Cardiovasc Med. 2009 Jun;10(6):446-53.

Warfarin reduces this incidence by two thirds and is the most effective agent for this indication.
The direct thrombin inhibitor dabigatran is furthest along in clinical development, followed by the factor Xa inhibitors rivaroxaban and apixaban.
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19074094 Dentali F, Crowther MA: Management of excessive anticoagulant effect due to vitamin K antagonists. . Am Heart J. 2009 May;157(5):805-10

In the absence of bleeding, such values may be treated with either simple warfarin withdrawal or the administration of low doses of oral vitamin K.
If the INR is in excess of 10, most experts would recommend the administration of vitamin K and, in the case of active bleeding, additional administration of coagulation factors either in the form of fresh frozen plasma (FFP) or prothrombin complex concentrates (PCC).
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18617125 Ilyas C, Beyer GM, Dutton RP, Scalea TM, Hess JR: Recombinant factor VIIa for warfarin-associated intracranial bleeding. . J Clin Anesth. 2008 Jun;20(4):276-9.

MEASUREMENTS: We examined initial and subsequent coagulation studies (prothrombin time, international normalized ratio [INR]), blood product requirement, and clinical outcome, including time to reverse anticoagulation, duration of reversal, and subsequent mortality.
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20059668 Schulman S, Spencer FA: Antithrombotic drugs in coronary artery disease: risk benefit ratio and bleeding. Am J Health Syst Pharm. 2008 Aug 1;65(15 Suppl 7):S13-21.

The classic anticoagulant unfractionated heparin is giving way to low-molecular-weight heparin, the pentasaccharide fondaparinux and the direct thrombin inhibitor bivalirudin.
Warfarin (or another vitamin K antagonist) and antiplatelet agents are often required in combination for several months.
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19909684 Ward WH, Platz TA, Pond KT, Southern FA, Moore EM: Iatrogenic venous pseudoaneurysm: case report and review of the literature. Vascular. 2009 Nov-Dec;17(6):355-8.

The patient, on warfarin therapy for chronic atrial fibrillation, described progressive swelling at a previous venipuncture site.
Although both thrombin injection and coil embolization have been described as nonsurgical treatment options for arterial pseudoaneurysms, surgical resection may be the most appropriate approach for those with a venous equivalent.
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18266660 Lip GY, Frison L, Grind M: Stroke event rates in anticoagulated patients with paroxysmal atrial fibrillation. Neurocrit Care. 2009 Dec 5.


AIMS: To test the hypothesis that stroke and systemic embolic events (SEE) in the stroke prevention using an oral thrombin inhibitor in atrial fibrillation (SPORTIF) III and V trials are different between paroxysmal and persistent atrial fibrillation (AF).
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18807678 Kalina M, Tinkoff G, Gbadebo A, Veneri P, Fulda G: A protocol for the rapid normalization of INR in trauma patients with intracranial hemorrhage on prescribed warfarin therapy. J Oral Maxillofac Surg. 2010 Feb 6.

To identify and expedite warfarin reversal, we designed a protocol to administer a prothrombin complex concentrate.
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19794141 Skupsky J, Zhang AH, Su Y, Scott DW: A role for thrombin in the initiation of the immune response to therapeutic factor VIII. Clin Evid. 2009 Jan 13;2009. pii: 0209.

If mice are treated with the anticoagulant warfarin, which depletes other coagulation factors including thrombin, there is a reduced immune response to FVIII.
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19741508 Fernlof G, Sjostrom BM, Lindell KM, Wall UE: Management of major bleedings during anticoagulant treatment with the oral direct thrombin inhibitor ximelagatran or warfarin. N Engl J Med. 2009 Dec 10;361(24):2342-52. Epub .
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