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Trial record 2 of 164 for:    warfarin AND Vitamin K

Does Low Dose Oral Vitamin K Improve International Normalized Ratio (INR) Stability? (OVWAC VII)

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: NCT00990158
Recruitment Status : Completed
First Posted : October 6, 2009
Last Update Posted : May 21, 2015
McMaster University
University of Western Ontario, Canada
Information provided by (Responsible Party):
Mark Crowther, St. Joseph's Healthcare Hamilton

Brief Summary:
Warfarin is highly effective for the prevention of both first and recurrent thrombotic events, however even minor excursions outside the reference INR range of 2.0 to 3.0 are associated with bleeding or thrombotic complications. The importance of maintaining the INR within the desired interval has led to the concept of "time in therapeutic range (TTR)" - the total proportion of time that the INR is between 2.0 and 3.0. The investigators propose a multicentre, double blind, randomized trial which will determine if 0.150 mg of oral vitamin K increases time in the therapeutic range for patients receiving warfarin.

Condition or disease Intervention/treatment Phase
Coagulation Bleeding Thrombosis Drug: Phytonadione (Vitamin K1) Drug: Placebo Phase 3

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 235 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Multicentre Study of Low Dose Oral Vitamin K for INR Control in Patients Receiving Warfarin
Study Start Date : July 2010
Actual Primary Completion Date : April 2014
Actual Study Completion Date : April 2014

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Active Comparator: Low dose vitamin K + usual warfarin
Low dose oral vitamin K (0.150 mg orally once daily) + warfarin continuation with usual warfarin monitoring
Drug: Phytonadione (Vitamin K1)
A daily dose of 150 micrograms of vitamin K medication given orally for a total of 7 months

Placebo Comparator: Usual warfarin therapy + placebo
Patients continue usual warfarin and take one placebo per day
Drug: Placebo
A daily dose of matching placebo medication given orally for a total of 7 months

Primary Outcome Measures :
  1. When compared with placebo does the addition of 150 micrograms of daily vitamin K to "usual warfarin therapy" improve anticoagulant control as measured by "time in the therapeutic range"? [ Time Frame: 7 Months ]

Secondary Outcome Measures :
  1. Does low dose Vitamin K (LDVK) increase the frequency of adverse clinical events, including thromboembolism and major and/or all bleeding? [ Time Frame: 7 Months ]

Information from the National Library of Medicine

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

Inclusion Criteria:

  • Warfarin therapy administered to a target INR of 2.0 to 3.0

Exclusion Criteria:

  • Out of range INR on day of screening - enrolment will only occur if the patient's INR on the day of screening is between 1.8 and 3.4 (inclusive) - if the INR is outside this range the patient will be re-screened when the INR is within this range.
  • Recent warfarin initiation - all patients must have received warfarin for a minimum of 3 months
  • Planned termination or extended temporary interruption of warfarin within 6 months or anticipated survival of less than 6 months
  • Known severe liver disease, known excess alcohol consumption , known malabsorption syndrome or inability to take oral medications
  • Use of medications known to interfere with warfarin and whose dose is likely to change over the course of the study (e.g. barbiturates, rifampin etc.)
  • Known allergy to vitamin K
  • Inability or unwillingness to follow study procedures or provide consent
  • Prior participation in this study, or participating in a competing study which may impact INR control

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): NCT00990158

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Canada, Ontario
Hamilton Health Sciences Centre
Hamilton, Ontario, Canada, L8L 2X2
St. Joseph's Hospital
Hamilton, Ontario, Canada, L8N 4A6
London Health Sciences Centre
London, Ontario, Canada, N6A 4G5
University Health Network, Toronto General Hospital
Toronto, Ontario, Canada, M5G 2C4
Sponsors and Collaborators
St. Joseph's Healthcare Hamilton
McMaster University
University of Western Ontario, Canada
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Principal Investigator: Mark A Crowther, MD McMaster University

Additional Information:
Crowther MA, Ageno W, Garcia D, Wang L, Witt DM, Clark NP, et al. Effectiveness of low dose oral vitamin K for patients with elevated INR values: results of a randomized trial examining clinical outcomes. Journal of Thrombosis & Haemostasis 5[S2], PS 219. 2008.
Proportion Difference Power / Sample Size Calculation. 8-7-2008.

Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: Mark Crowther, Vice President, Research, St. Joseph's Healthcare Hamilton Identifier: NCT00990158    
Other Study ID Numbers: NA 6695
First Posted: October 6, 2009    Key Record Dates
Last Update Posted: May 21, 2015
Last Verified: December 2013
Keywords provided by Mark Crowther, St. Joseph's Healthcare Hamilton:
Vitamin K1 (phytonadione)
Randomized controlled trial
Time in therapeutic range
VKORC1 and CYP2C9 genotypes
Time INR in therapeutic range
Additional relevant MeSH terms:
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Vitamin K
Vitamin K 1
Pathologic Processes
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Growth Substances
Physiological Effects of Drugs
Antifibrinolytic Agents
Fibrin Modulating Agents
Molecular Mechanisms of Pharmacological Action