Practice Information

Coumadin (Warfarin) Managed Dosing by Nurses

To: Interested Parties

From: Barbara Zittel, RN, Ph.D, Executive Secretary, State Board for Nursing

Subject: RN Managed Coumadin (Warfarin) Dosing

Date: March 2009

The Board has been asked to opine on Coumadin (Warfarin) dosing managed by Registered Professional Nurses (RNs) based on written protocols.

As background information, Coumadin (Warfarin) is taken by mouth to inhibit vitamin K, which is essential for effective production of clotting factors II, VII, IX, X, and anticoagulant proteins C&S. Coumadin (Warfarin) is given once daily. It is monitored by the prothrombin time and the international normalized ratio (INR). When the INR falls below 2.0, thrombosis risk increases and when the INR rises above 4.0, serious bleeding risk increases. Thus, there is a critical need for monitoring Coumadin's (Warfarin's) effect. Typically, initial monitoring is conducted on a daily basis until the INR is within therapeutic range for at least two consecutive days. Then INR monitoring is performed two to three times a week for one to two weeks. If the patient remains stable, this interval can be widened to a monitoring frequency of once every four to six weeks. If dosage adjustments are necessary, INR monitoring is once again performed more often until a new state of stability is achieved.

The Board for Nursing has stated that in certain limited situations the development of a standardized list of orders designed for a given patient population may be lawful if such a list of orders is signed by the patient's primary care provider and customized to the particular needs of a specific patient prior to an RN initiating the list of orders. Such orders are to be administered based on a predetermined order which is informed, for example, by a pain scale or an algorithm for each patient and executed in the same manner as any other "as needed" order. The dosing of Coumadin (Warfarin) by RNs would appear to be able to follow such a model given the following guidelines:

  • A written patient specific treatment protocol is developed based on standards of care that includes:
    • an algorithm that includes the formula for the initial dose of Coumadin (Warfarin), the formula for changing Coumadin (Warfarin) dose if the International Normalized Ratio (INR) is subtherapeutic or above therapeutic range, when to hold Coumadin (Warfarin), and when it is appropriate to administer vitamin K and at what dose,
    • the therapeutic range for clinical problems such as atrial fibrillation, deep vein thrombosis, congestive heart failure, stroke, etc.,
    • identification of how the INR will be measured, for example, an INR calculated from a venipuncture sample is more accurate than from some finger stick methods,
    • frequency of supplementary diagnostic tests to assess bleeding such as hemoglobin and hematocrit, urinalysis, fecal occult blood,
    • the frequency of follow-up visits, initially and when stabilized,
    • type of visit, that is, office, telephone, or both,
    • criteria for hospital admission,
    • patient education.
  • The protocol must have written approval by the appropriate review entity of the facility/practice.
  • The protocol is invoked after the patient has been seen by an authorized prescriber such as a physician or nurse practitioner, who determines the appropriateness of the protocol and orders it for a specific patient.
  • The protocol must indicate a length of time after which it must be reordered.
  • The protocol must be located on the patient's record/chart.
  • The facility/practice must identify a clear line of communication for the RN to contact the authorized prescriber with questions or concerns.
  • The facility/practice must have a written policy and procedure for RN managed Coumadin (Warfarin) dosing including a rationale based on patient characteristics, that identifies when the RN managed Coumadin (Warfarin) protocol can be invoked, for example, only after INR levels are within a therapeutic range.
  • The facility/practice must document provisions made for initial and annual updates in education and skill training for each RN who is to provide Coumadin (Warfarin) dosing that addresses proper technique and hazards including contraindications for such therapy and how to handle unexpected outcomes/emergencies.
  • The RN must be able to document initial training and annual updates of appropriate education, skill training and clinical competence in: the pharmacology of Coumadin (Warfarin), including precautions, contraindications, signs and symptoms of adverse reactions and overdose; patient education and strategies to increase compliance; and evaluating prothrombin and INR levels to safe guard the patient against risks or complications.
  • Competency assessment must be documented in the personnel file of each RN and updated annually.
  • The RN must be designated by the facility/practice to carry out the procedure.

Failure to comply with these guidelines may place the RN at risk for a charge of unprofessional conduct.

It is not within the scope of practice of a Licensed Practical Nurse to manage Coumadin (Warfarin) dosing.

If you have additional questions, please contact Barbara Zittel, Executive Secretary to the State Board for Nursing:; phone: 518-474-3817 ext. 120; or fax: 518-474-3706.

Last Updated: January 31, 2013