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

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified July 2005 by National Taiwan University Hospital.
Recruitment status was:  Recruiting
Information provided by:
National Taiwan University Hospital Identifier:
First received: November 1, 2005
Last updated: NA
Last verified: July 2005
History: No changes posted

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 Intervention
Deep Venous Thromboembolism Drug: warfarin

Study Type: Interventional
Study Design: 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

Resource links provided by NLM:

Further study details as provided by National Taiwan University Hospital:

Estimated Enrollment: 120
Study Start Date: July 2005
Estimated Study Completion Date: June 2006

Ages Eligible for Study:   18 Years to 80 Years   (Adult, Senior)
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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00247702

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

National Taiwan University Hospital Recruiting
Taipei, Taiwan, 100
Contact: Tsay Wei, Doctor    886-2-23123456 ext 5040   
Sponsors and Collaborators
National Taiwan University Hospital
Study Chair: Tasy Wei, Doctor National Taiwan Univerisity Hospital
  More Information Identifier: NCT00247702     History of Changes
Other Study ID Numbers: 940609
Study First Received: November 1, 2005
Last Updated: November 1, 2005

Keywords provided by National Taiwan University Hospital:

Additional relevant MeSH terms:
Venous Thromboembolism
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Anticoagulants processed this record on September 19, 2017