NCT00794755

Low Dose Supplementation to Improve Anticoagulation Control With Oral Vitamin K as an Adjuvant to Warfarin Therapy

A Phase III Pilot RCT (Randomized, Controlled Trial) to Assess the Effectiveness of Low Dose Vitamin K1 (200 Micrograms Per Day) on Improving Anticoagulation Control in Unstable Patients on Warfarin

• Status: Completed
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 100 (estimated)
• Sponsor: Ottawa Hospital Research Institute · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

The main objective of this study is to assess the effectiveness of low dose Vitamin K1 (200 micrograms per day) at improving anticoagulation control in unstable patients on warfarin. This study will also aim to look at effectiveness in the context of genes known to influence warfarin metabolism, variability in the consumption of Vitamin K rich foods, and patient knowledge about warfarin anticoagulation -- factors which have been associated with anticoagulation control and which can influence the effectiveness of this intervention in clinical practice.

Detailed description

A double-blinded placebo controlled pilot RCT assessing the effectiveness of daily supplementation with low dose Vitamin K1 (200 micrograms per day) against placebo at improving anticoagulation control. Previous studies assessing the efficacy of this intervention have been small and further trials are required to evaluate the true effectiveness and safety profile. Furthermore the impact of genetic polymorphisms, known to impact warfarin metabolism, on the effectiveness/safety of this intervention will also be assessed in this study. Demographic and clinical variables as well as potential confounding variables such as variable dietary Vitamin K intake, concomitant interacting medications, and anticoagulation knowledge will be assessed in this study. Given that this is a pilot study we will be looking at recruitment numbers and necessary parameter estimates to determine the number of patients available at our institution for the study. Power analysis will be performed to evaluate the treatment effect size between the placebo and intervention groups.

Conditions

• Coagulation

Interventions

Type	Name	Description
DIETARY_SUPPLEMENT	Vitamin K1 (Phytonadione)	Vitamin K1 tablets (100 micrograms per tablet) will be taken by patients randomized to the Vitamin K arm. Dosage is two tablets per day (200 micrograms per day) to be taken with warfarin for the 6 month study period.
DIETARY_SUPPLEMENT	Placebo	Lactose-based placebo tablets (identical in appearance to the Vitamin K1 tablets) will be taken by patients randomized to the placebo arm. Dosage is two tablets per day to be taken with warfarin for the 6 month study period.

Timeline

• Start date: 2008-11-01
• Primary completion: 2010-04-01
• Completion: 2010-04-01
• First posted: 2008-11-20
• Last updated: 2011-07-27

Locations

1 site across 1 country: Canada