Evaluation of Maintenance Dosing vs Loading Dosing Upon Restarting Warfarin Therapy: A Prospective Randomized Trial

University of Alberta

Status and phase

Completed

Phase 1

Conditions

Anticoagulation

Treatments

Drug: Warfarin

Drug: warfarin

Study type

Interventional

Funder types

Other

Identifiers

NCT01124058

2007UHFMDvsLD

Details and patient eligibility

About

A prospective, randomized trial to compare the time taken to achieve a therapeutic INR upon re-starting warfarin at a "loading" dose (namely 1.5 times the "maintenance" dose for 3 days) compared to the known "maintenance" dose.

Full description

Patients will be identified via the University of Alberta Hospital Anticoagulation Management Service. Following the receipt of written, informed consent, patients will be randomized to re-start warfarin at their "maintenance" dose or at a "loading" dose (1.5 times the maintenance dose for 3 days, then resumption of warfarin dosing as per the maintenance dose). Randomization will be performed on-line through the EPICORE Centre.

Assuming Day 1 is the day warfarin is re-started, patients will have INRs done on day 3 and at least every 2 days thereafter until a therapeutic INR is obtained. In addition, protein C, protein S and factor II levels will be obtained while the patient is on stable maintenance dosing of warfarin (i.e., prior to holding warfarin for the procedure), 7 days after re-starting warfarin, and 14 days after re-starting warfarin. Complete blood counts (CBCs) will be done with each INR if the patient is taking a low molecular weight heparin (LMWH). Patients will have their anticoagulant therapy managed by the AMS for 6 weeks and will receive a telephone follow-up by the AMS at 90 days to determine if any bleeding or clotting complications occurred.

Enrollment

39 patients

Sex

All

Ages

18+ years old

Volunteers

No Healthy Volunteers

Inclusion and exclusion criteria

Inclusion Criteria:

Have 'stable warfarin maintenance dosing' (defined as last 2 INRs within therapeutic range with weekly warfarin dosing not being changed any more than 10%)
Have an INR indicative of not taking any warfarin (INR <1.4) or confirmation of the patient not taking any warfarin in the past 4 days
Provide written, informed consent