Daily Vitamin K in Patients on Warfarin With Unstable INRs

Use of Daily Vitamin K Supplementation in Patients on Warfarin With a History of Frequent Dose Changes or Variable INRs

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00287313

Enrollment

Registered

2006-02-06

Start date

2005-10-31

Completion date

2006-05-31

Last updated

2010-01-12

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Anticoagulants, Warfarin

Keywords

Unstable INRs, Warfarin, Vitamin K

Brief summary

The purpose of this study is to determine if daily Vitamin K supplementation stabilizes INRs in patients taking warfarin with a history of frequent dose changes or variable INRs.

Detailed description

Consistent daily Vitamin K intake may contribute to the stabilization of INR values in patients with unstable INRs on warfarin therapy. Subjects with unstable INRs will be identified from the existing patient records of the UNC Anticoagulation Clinics. Eligible subjects will sign an informed consent form and will receive a point-of-care (POC) INR monitoring device. They will undergo 9 weeks of home INR monitoring via the POC device (with monthly clinic follow-up). They will subsequently be provided with 500 mcg Vitamin K tablets to be taken once daily. Weekly POC INR monitoring with monthly clinic follow-up will continue for an additional 8 weeks.

Interventions

DRUGVitamin K

Study design

Allocation

NON_RANDOMIZED

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

Inclusion criteria

* Patient of UNC Anticoagulation Clinic with INR target of 2.0-3.0 and at least 9 months on uninterrupted warfarin * Unstable INRs for the past 6 months, defined as a minimum number of warfarin dose changes of 3 * Patient demonstration of proper POC device technique on 2 measurements during one teaching session with investigator * Age greater than or equal to 18 years

Exclusion criteria

* Stroke or TIA within the previous 12 months * VTE within the last 3 months * Antiphospholipid antibody syndrome * Pregnant patients, since warfarin is contraindicated during pregnancy

Design outcomes

Primary

Measure	Time frame
Time in therapeutic, sub-, and supra-therapeutic range	—
Variance/SD of INRs for each patient	—
Number of warfarin adjustments required in each phase	—
Adherence assessed by pill counts and pharmacy record review	—
Thrombotic/bleeding episodes	—

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026