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

The recruitment status of this study is unknown because the information has not been verified recently.
Verified December 2011 by University of Alberta.
Recruitment status was  Recruiting
Sponsor:
Information provided by (Responsible Party):
Tammy Bungard, University of Alberta
ClinicalTrials.gov Identifier:
NCT01124058
First received: May 13, 2010
Last updated: December 6, 2011
Last verified: December 2011
  Purpose

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.


Condition Intervention Phase
Anticoagulation
Drug: warfarin
Drug: Warfarin
Phase 1

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Evaluation of Maintenance Dosing vs Loading Dosing Upon Restarting Warfarin Therapy: A Prospective Randomized Trial.

Resource links provided by NLM:


Further study details as provided by University of Alberta:

Primary Outcome Measures:
  • re-starting warfarin "loading" dose vs "maintenance" dose [ Time Frame: INR drawn 3 days post-reinitiation and then every 2 days until therapeutic ] [ Designated as safety issue: Yes ]
    To compare the time taken to achieve a therapeutic INR between those patients re-starting warfarin with a "loading" dose and a "maintenance" dosing regimen using linear interpolation of INRs.


Secondary Outcome Measures:
  • Compare % of time within, above and below the target INR range [ Time Frame: days ] [ Designated as safety issue: No ]
    To compare the % of time within, above and below the desired INR range between those patients re-starting warfarin with a "loading" dose or "maintenance" dose 6 weeks following restarting warfarin.

  • Compare bleeding/clotting complications between two groups [ Time Frame: 30 days, 90 days ] [ Designated as safety issue: No ]
    To compare the rates of thrombosis (i.e., stroke) / major hemorrhage between those re-starting warfarin with a "loading" dose or "maintenance" dose at 30 days and 90 days following restarting warfarin.

  • Compare the levels of protein C, protein S, and factor II between 2 groups. [ Time Frame: week ] [ Designated as safety issue: No ]
    To compare the levels of protein C, protein S, and factor II between those re-starting warfarin with a "loading" dose or "maintenance" dose.


Estimated Enrollment: 40
Study Start Date: June 2010
Estimated Primary Completion Date: December 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
No Intervention: Loading
1.5 times the maintenance dose for 3 days, then resumption of warfarin dosing as per the maintenance dose
Drug: warfarin
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).
Other Name: warfarin, Taro-warfarin, Apo-warfarin, Coumadin, Fragmin, Low-molecular weight heparin
No Intervention: Maintenance
Re-start same dose as previously stable on
Drug: Warfarin
"Maintenance" dose is the amount of warfarin that a patient required to maintain a therapeutic INR.
Other Name: warfarin, Taro-warfarin, Apo-warfarin, Coumadin, Fragmin, Low-molecular weight heparin

Detailed 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.

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01124058

Contacts
Contact: Tammy J Bungard, BSP, PharmD 780-492-2906 tammy.bungard@ualberta.ca
Contact: Amy N Machnik 780-492-2906 amy.machnik@albertahealthservices.ca

Locations
Canada, Alberta
Univeristy of Alberta Recruiting
Edmonton, Alberta, Canada, T6G 2C8
Contact: Tammy Bungard, BSP, PharmD    780-492-2906    tammy.bungard@ualberta.ca   
Contact: Amy Machnik    780-492-2906    amy.machnik@albertahealthservices.ca   
Sponsors and Collaborators
University of Alberta
Investigators
Principal Investigator: Tammy J Bungard, BSP, PharmD Univeristy of Alberta
Principal Investigator: Bruce Ritchie, MD, FRCPC University of Alberta
  More Information

No publications provided

Responsible Party: Tammy Bungard, Principal Investigator, University of Alberta
ClinicalTrials.gov Identifier: NCT01124058     History of Changes
Other Study ID Numbers: 2007UHFMDvsLD
Study First Received: May 13, 2010
Last Updated: December 6, 2011
Health Authority: Canada: Health Canada
Canada: Ethics Review Committee

Keywords provided by University of Alberta:
restarting warfarin
time to therapeutic INR

Additional relevant MeSH terms:
Dalteparin
Heparin
Heparin, Low-Molecular-Weight
Warfarin
Anticoagulants
Cardiovascular Agents
Fibrin Modulating Agents
Fibrinolytic Agents
Hematologic Agents
Molecular Mechanisms of Pharmacological Action
Pharmacologic Actions
Therapeutic Uses

ClinicalTrials.gov processed this record on November 20, 2014