Toggle site contrast Toggle Contract

Administration of anticoagulation and warfarin

For all staff responsible for administering warfarin in care homes

Background

Anticoagulants are medicines that help to prevent blood clots. They are given to people at high risk of getting clots, to reduce their chances of developing serious conditions such as strokes and heart attacks.

Anticoagulants are one of the medicines most frequently identified as causing preventable harm and admission to hospital. Nationally it is recognised that procedures promoting safe administration and monitoring of warfarin can reduce the risk of harm and improve care.

Examples of anticoagulants include:

  • direct oral anticoagulants (DOACs), including Apixaban, Dabigatran, Edoxaban and Rivaroxaban
  • injectable anticoagulants, also known as low molecular weight heparin
  • warfarin.

Aim or purpose

To support safer administration of anticoagulants and highlight monitoring requirements and side effects to look out for when care home staff administer anticoagulants.

Common conditions associated with the use of anticoagulants

Atrial fibrillation (AF)

A heart condition that causes an irregular and often abnormally fast heart rate. People with AF have an increased risk of developing blood clots, which can lead to a stroke.
Treatment for AF is normally long term.

Deep Vein Thrombosis (DVT)

A blood clot forms in one of the deep veins in the body, usually in the legs, causing pain and swelling. Duration of treatment for DVT will vary for each person and will depend on a range of factors.

Pulmonary embolism (PE)

Blood clot blocks one of the blood vessels around the lungs, stopping the supply of blood to the lungs. Duration of treatment for PE will vary for each person and will depend on a range of factors.

Recent hip or knee replacement

People may be prescribed an anticoagulant to prevent blood clots until they are able to move around. Treatment is usually short term.

Side effects of anticoagulants

Bleeding is a common side effect of all anticoagulants, including warfarin, and it can occur in any part of the body.

Get immediate medical advice if spontaneous bleeding occurs whilst taking an anticoagulant and the bleeding does not stop or recurs. You should also get advice for:

  • bruising
  • bleeding gums
  • nosebleeds
  • prolonged bleeding from cuts
  • blood in urine or stools
  • vomiting blood or coughing up blood
  • vaginal bleeding in a postmenopausal woman.

Anticoagulants and falls

Take special care if a resident has a fall while taking an anticoagulant, as there’s a higher risk of internal bleeding. Care home staff must follow their local care home protocol/falls pathway.

Importance of regular monitoring for residents taking Warfarin

Warfarin increases the time that it takes blood to clot. It’s measured by monitoring a patient’s International Normalised Ratio (INR).

What is an INR?

It’s a ratio comparing how long it takes for an individual’s blood to clot compared to an individual not taking warfarin. For example, a patient with an INR reading of 2.6 means it takes 2.6 times longer for their blood to clot compared with a person not on warfarin.

How do I measure an INR?

A patient’s INR is measured by doing a blood test. The frequency of the blood tests depends on whether the results are within the INR target range.

The most common target INR range is 2 to 3. For every patient on warfarin, there should be a target INR range recorded in their yellow book or equivalent anticoagulant record log, as well as the reason why the patient is on warfarin and the duration of their treatment.

What can affect the INR result?

The INR result depends on the dose of warfarin administered. It can also be affected by changes in medication (including over the counter and herbal supplements), diet, alcohol consumption, smoking, weight changes and acute illness. The administration of some foods and sip feeds can also affect the INR.

What do warfarin tablets look like?

Warfarin is available in four different strengths of tablets which are colour coded as:

  • 500micrograms (white)
  • 1mg (brown), 3mg (blue)
  • 5mg (pink).

Carers should be aware not to confuse warfarin tablets that may be similar such as a 500mcg (micrograms) dose and a 5mg (milligram) dose.

Monitoring other anticoagulants

Other anticoagulants don’t need monitoring, but DOACs require annual blood tests for monitoring. This is less stringent than the monitoring required for Warfarin.

Recommendations for care homes medication policy

The care homes medicines policy should include a Standard Operating Procedure (SOP) on the safe administration and monitoring of warfarin.

This should state the:

  • process for ensuring the safe administration, monitoring and communication requirements.
  • requirement for cross checking the last INR result, when the next blood test is due, and the current dose EVERY time warfarin is administered
  • care staff who administer anticoagulants or support people to take their own must be trained to undertake their duties safely.

The National Patient Safety Agency (NPSA) recommends that oral anticoagulants are administered from the original packs dispensed for individual patients. Monitored Dosage Systems are not flexible enough to cope with frequent dose changes and are not recommended for anticoagulants. Care homes should make safe arrangements with their local pharmacist or dispensing doctor.

Residents on anticoagulants or Warfarin are at risk of serious bleeding with NSAIDs, for example, Ibuprofen, Diclofenac, Naproxen. Residents care plans should include extra caution if homely remedies or over the counter (OTC) products with NSAIDs are used.

Responsibilities of the anticoagulant clinic

All residents taking warfarin must have an individual fully completed Yellow Book (NHS oral anticoagulant therapy – Important Information for Prescribers) or equivalent anticoagulant record log.

INR tests are generally carried out by care support workers who will complete the INR test then take the yellow book back to the hospital base for the warfarin dose to be calculated by a trained nurse. The yellow book will always be posted back the same working day, and an email sent by the end of the working day with dosing advice.

The anticoagulant service/prescriber must confirm the dose in writing following any INR blood test check. This is regardless of a dose change. If the prescriber wishes to make changes by telephone, this must be followed up by written confirmation (for example, letter, email) stating the latest INR result and confirmation of the dose.

Additional blood tests may be necessary if the resident has changes to other medicines that interact with the anticoagulant (for example, antibiotics). If this happens, the doctor/pharmacist/nurse will inform the resident and their carer. It’s important for the carer to contact the anticoagulant service and identify any new monitoring requirements.

Responsibilities of the care home

All communication regarding INR results should be kept with the residents Yellow Book or equivalent anticoagulant record log.

All care homes must have an NHS.NET email address in order for the warfarin clinic to send patient sensitive information regarding warfarin dosage.

Register for an NHS.NET email address

The yellow book or other INR record sheets (if not kept by the patient themselves) and any written confirmation must be stored with the residents Medication Administration Record (MAR) chart for cross-referencing.

If a resident is transferred to another care setting, the yellow book (or equivalent anticoagulant record log), INR result sheets, a copy of the MAR sheet and any other written information received must be sent with the resident. If the resident is temporarily transferred (for example, admitted to hospital) then copies of the above information must be sent with the resident.

Any missed doses within the last two weeks will affect the INR result. The anticoagulant service MUST be informed of any missed warfarin doses. It must also be informed if a resident is refusing or unable to take warfarin.

It’s important for warfarin to be taken at the same time each day. If a dose is missed or a higher than the recommended dose is taken, the anticoagulant clinic and the GP MUST be informed.

The anticoagulant clinic should be notified of any changes in medication, diet, hydration and lifestyle that could affect the warfarin.

If there are any issues with adherence of blood monitoring, seek further advice from GP and anticoagulant clinic to see if alternative anticoagulants may be more suitable if clinically appropriate.

Recording of information

The dose of warfarin intended for the resident must be clearly stated on the Medication Administration Record (MAR) chart. It’s good practice to have the Medication Administration Record (MAR) chart checked and signed by a second member of staff for accuracy after this information has been added.

Ensure the number of milligrams (mg) of warfarin required is stated on the Medication Administration Record (MAR) charts, not the number of tablets.

Warfarin should never be administered without adequate and regular monitoring of the INR.

It’s essential that there’s a safe system to ensure that information on INR results and dose to be taken via any written communications, yellow book, INR result sheets and MAR chart are cross-referenced for correlation that the correct dose is being taken.

Two anticoagulants should not be given together unless in exceptional cases, for example, bridging. If unsure please raise with the senior lead at the care home.

Recording of information

Contact us

BHT contact information

01296 315000

Anticoagulation Clinic, Monday to Friday 9am  to 5pm

01494 323600
buc-tr.anticoagulation@nhs.net

Document Details