The Effect of Medication Timing on Anticoagulation Stability in Users of Warfarin: The "INRange" RCT

• Status: Completed
• Trial end date: 2018-04-27
• Target enrollment: 0
• Participant gender: All

Summary

Warfarin is an anticoagulant medication that is highly effective at preventing clotting disorders but which has a narrow therapeutic window. If warfarin is under effective patients are at risk of stroke, if it is over effective patients are at risk of bleeding complications. Physicians routinely and regularly measure a blood test (called the "INR") that determines the effectiveness of warfarin and have a range of test values (the "therapeutic range") in which they try to keep the patient. By convention warfarin is taken at dinnertime, however this is the same time of day that highly variable consumption of dietary vitamin K occurs (found largely in green leafy vegetables) and vitamin K alters the effectiveness of warfarin. Given vitamin K has a very short half-life (i.e. it is only active for a short period of time after it is ingested) it may make more sense to take warfarin in the morning (when very little vitamin K is ingested) to produce a more consistent drug effect. The purpose of this study is to determine whether switching current warfarin users from evening to morning dosing decreases time spent outside the therapeutic INR range.

• Phase: Phase 4
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: University of Alberta
• Collaborator: Vancouver Coastal Health Research Institute
• Treatments: Warfarin

Criteria

Inclusion Criteria:

• Dinner or evening use of warfarin

• ≥ 3 months of continuous warfarin use

• Expectation of long-term warfarin use

• Baseline INR data made available by family physician

• Community dwelling

Exclusion Criteria:

• Patient is palliative

• Patient is unable to provide informed consent