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The Association of Warfarin Dosage and Plasma Enantiomer Concentration With the Gene Polymorphisms of CYP and VKOR

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00247702
Recruitment Status : Unknown
Verified July 2005 by National Taiwan University Hospital.
Recruitment status was:  Recruiting
First Posted : November 2, 2005
Last Update Posted : November 2, 2005
Information provided by:
National Taiwan University Hospital

Brief Summary:

Oral warfarin anticogulation for the prevention and treatment of patients with venous thromboembolism is one of the most used therapies in clinical practice. Patients require different dosage to achieve the target therapeutic anticoagulation. Optimal dosage and bleeding complication are two most clinical concerns. Besides of multiple individual factors (e.g. age, dietary intake, vitamin supplement, drug compliance etc.), some genetic factors may determine the drug requirement and safety.

The cytochrome P450 CYP2C9 is a liver enzyme required for the oxidative metabolism of warfarin. The vitamin K epoxide redutase (VKOR) is a liver enzyme associated with the reuse of the oxidative hydroquinone form of vitamin K. The VKOR enzyme is the target of warfarin. Recent studies revealed both genes may determine the pharmacodynamic of warfarin anticogualation. To date, there are more than thirteen identified polymorphism at CYP2C9 gene. Majority of those variant polymorphisms may decrease the warfarin requirement. The VKOR complex subunit 1 (VKORC1) is a newly identified gene. Some polymorphisms also were reported.

As we know, the Chinese patients need a lower dosage of warfarin in comparison with the Caucasian patients. We are interested in finding the genetic causes of Taiwneses Chinese patients. In our study we will first identify the polymorphism patterns of these two genes in normal population. Then, we will try to find the association between these polymorphism and patient warfarin requirement. Our pharmacogenetics study will be valuable for prevention of bleeding complication of warfarin treatment in Chinese population.

Condition or disease Intervention/treatment Phase
Deep Venous Thromboembolism Drug: warfarin Not Applicable

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Study Type : Interventional  (Clinical Trial)
Enrollment : 120 participants
Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Study of the Association of Warfarin Dosage and Plasma Enantiomer Concentration With the Gene Polymorphisms of CYP and VKOR
Study Start Date : July 2005
Study Completion Date : June 2006

Resource links provided by the National Library of Medicine

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Use warfarin therapy for at least two months before study
  • Stable INR value during recent three months

Exclusion Criteria:

  • higher age(>80 y/o)
  • liver and renal dysfunction
  • alcohol abuse
  • BMI<18kg/m2
  • coadministered medicine that can affect pharmacokinetics or pharmacodynamics of warfarin

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00247702

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Contact: Tsay Wei, Doctor 886-2-23123456 ext 5040

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National Taiwan University Hospital Recruiting
Taipei, Taiwan, 100
Contact: Tsay Wei, Doctor    886-2-23123456 ext 5040   
Sponsors and Collaborators
National Taiwan University Hospital
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Study Chair: Tasy Wei, Doctor National Taiwan Univerisity Hospital

Layout table for additonal information Identifier: NCT00247702    
Other Study ID Numbers: 940609
First Posted: November 2, 2005    Key Record Dates
Last Update Posted: November 2, 2005
Last Verified: July 2005
Keywords provided by National Taiwan University Hospital:
Additional relevant MeSH terms:
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Venous Thromboembolism
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases