The role of the pharmacist in warfarin therapy - Amazon AWS

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Day-to-day life for a patient on warfarin. Taking warfarin can have an impact on how a patient lives their day-to-day li
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Module 1850

The role of the pharmacist in warfarin therapy From this pharmacy CPD module on the role of the pharmacist in warfarin therapy you will learn: • • • •

How long patients will be on warfarin therapy What a patient should do if they miss a dose Advice you can provide on day-to-day life for these patients What you should consider when dispensing warfarin

PHILIP CRILLY, PHARMACY TEACHING FELLOW As warfarin is such a common drug, pharmacists and their staff need to understand their role in ensuring its safe and effective use. How international normalised ratio (INR) is measured, and some of the common interactions of warfarin, are outlined in CPD module 1849 (see bit.ly/CD1849). This module will focus on the role of the pharmacist and their staff in warfarin therapy. As a pharmacist, your first role is to ensure your patients who have been prescribed warfarin get all the appropriate verbal and written information they need in order to take the drug safely. One of the key sources your patients should have is their oral anticoagulant therapy book, also known as the ‘yellow book’. This contains all the vital information relating to their therapy, including why they have been prescribed warfarin, their target INR, and their current warfarin dose. It is important to remember that doses in the yellow booklet should always be expressed in milligrams (mg) and not in number of tablets,

need to be cautious with (see bit.ly/CD1849). Patients are usually advised to take their warfarin in the evening, at around 6pm. The rationale behind this is that if the patient has had their INR level checked on that day, then they can adjust their dose straight away. However, taking warfarin in the evening is not mandatory. If it is more convenient for a patient to take warfarin at another time – for example, in the morning with their other prescribed medicines – then this is acceptable. The most important point is that the patient takes their warfarin at the same time each day.

that they should not take a double dose to make up for a forgotten dose. It is important that a missed dose is recorded in the patient’s anticoagulant booklet. For those patients who regularly forget to take their medications, they may ask for – or you may be tempted to suggest – a dosette box. However, the use of these monitored dosage systems is not generally recommended for anticoagulants, due to the frequent need to adjust doses.

Day-to-day life for a patient on warfarin

What should a patient do if they miss a dose?

Taking warfarin can have an impact on how a patient lives their day-to-day life. Although they can live normal lives, there are a range of things these individuals may need to consider:

If a patient forgets to take a dose at the correct time, you should recommend that they take it as soon as they remember, unless it is nearly time for the next dose. You should explain to patients

Sport and exercise Patients taking warfarin are not restricted from playing sport, but they do need to be cautious

as there is the possibility that patients may be confused and take an incorrect dose. Although their dose should be recorded in the book, when handing out a dispensed warfarin prescription, it is still important to remind the patient of their current dose and when they need to go for their next INR test.

Warfarin duration Depending on the condition being treated, the length of time a patient will be treated with warfarin will vary. For example, if a patient is undergoing a cardioversion – a procedure that restores a normal heart rhythm in people with arrhythmia – they are required to take warfarin for three weeks before, and four weeks after, the procedure. For the treatment of a pulmonary embolism, a patient will usually take warfarin for six months, while for atrial fibrillation they may need to take warfarin for the rest of their life.

How should warfarin be taken? Warfarin can be taken with or without food, but there are certain foods and drinks that patients

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about sports that involve body contact – such as football and rugby – where the risk of injury and bleeding may be higher. Non-contact sports – such as swimming and running – are generally fine. Vaccinations It is fine to have vaccinations while on warfarin. In fact, some pharmacist-led warfarin clinics offer the flu vaccination to patients when they come in to have their INR levels checked. With any injection there is always the risk of bleeding, but as long as INR levels are within the therapeutic range there should be no increased risk of bleeding. Piercings and tattoos You should warn patients considering getting either piercings or tattoos not to have these done while taking warfarin. This is because these procedures carry an increased risk of bleeding, as well as infection if the site is not kept clean. These factors can complicate warfarin therapy, and as such should be avoided. Travelling For warfarin patients travelling abroad, one of the most important considerations is when they should take their medication in a new time zone. There are a couple of different methods you can suggest for dealing with this: • For shorter trips, you can advise the patient to maintain their dose at their ‘home’ time. For example, if they take their medicine at 6pm in the UK, then they should take it at 1pm when in New York. • For longer trips, they can slowly try to adjust their dose before they leave the UK. This will involve taking their warfarin two hours earlier or later (depending on the destination’s time difference) each day until they are aligned, so that they are able to take their medcine at – for example – 6pm local time. Whatever the circumstance of travel, you should

advise the patient to inform their prescriber, as they may wish to test the patient’s INR before the trip, or encourage them to have their INR tested while travelling. Patients who have recently been treated for deep vein thrombosis (DVT) and are considering flying should check whether this is appropriate with their specialist. Extra precautions may need to be taken to ensure that the thrombosis does not reoccur. For example, wearing compression stockings during flights of four hours or longer can significantly reduce the risk of DVT, as well as leg swelling (oedema).

Major bleeds If the individual has major bleeding, they will need to stop their warfarin immediately and you should refer them urgently to hospital. The normal treatment for a warfarin patient with a major bleed is intravenous treatment with phytomenadione (vitamin K1), in combination with dried prothrombin complex concentrate or fresh frozen plasma.

Practicalities of dispensing warfarin prescriptions Most pharmacy standard operating procedures (SOPs) should include guidance indicating that pharmacists should always ask patients for their anticoagulant book when dispensing medication. On the patient’s medication record (PMR), you should record the date of the most recent INR test, the result, and the current

Everyday scrapes and knocks You should advise patients taking warfarin to seek medical attention if they cut themselves and are unable to stop the bleeding. In addition, if they experience a blow to the head or body, they should seek medical support from their local A&E department, as it may not be immediately obvious that they have internal bleeding. You should encourage patients to carry their anticoagulant booklet with them at all times. This ensures that if they do require medical treatment – whether an emergency or not – those treating them know they are taking warfarin and what dose they are currently on. Going to the dentist You should explain to patients that they are able to go to their dentist – as the majority of treatments can go ahead as planned – without having to stop or alter their anticoagulant dose. However, you should advise them to take their recent INR results in their yellow booklet with them, so the dentist can ensure it is safe to treat them. If the patient is attending an appointment with a new dentist, they should ensure the new practice is aware of their medical conditions and current treatments.

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recommended dose. If a patient does not have their anticoagulant book to hand, or cannot remember the details it contains, you should still make a note of this exchange in the PMR. When labelling warfarin tablets, you should write “take as directed in your anticoagulant book”, and then counsel the patient to ensure they understand what their current dose is and when they will need to go for their next INR test. Counselling should also involve discussing the different colours of warfarin tablets; for example, explain clearly that 0.5mg tablets are

The role of the pharmacist in warfarin therapy CPD

white, 1mg tablets are brown, 3mg tablets are blue and 5mg tablets are pink. These are useful indicators for patients, and you may often come across patients discussing taking certain combinations of colours on a given day.

Alternatives to warfarin therapy Alternatives to warfarin therapy include novel oral anticoagulant drugs (NOACs), or direct oral anticoagulant drugs (DOACs) as they are also known. In terms of efficacy, NOACs/DOACs are just as effective as warfarin. There are four

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Reflect How long should patients with a pulmonary embolism take warfarin for? When is the best time of day for patients to take their warfarin? What precautions should warfarin patients take when going to the dentist?

1. Warfarin doses in the yellow anticoagulant book should always be expressed in milligrams. True or false

Plan This article contains information about warfarin therapy, including how long patients should take warfarin for and what to do if a dose is missed. Advice that pharmacists can provide for patients on warfarin, and the considerations required when dispensing warfarin prescriptions, are also discussed.

2. For the treatment of atrial fibrillation, a patient will usually need to take warfarin for six months. True or false

Act • Revise your knowledge of the yellow patient anticoagulant therapy book on the NHS patient safety website at tinyurl.com/warfarin13 • Make sure that all patients who have been newly prescribed warfarin are offered a new medicine service (NMS) review. Make sure all other warfarin patients have regular medicines use reviews (MURs). • Find out about anticoagulant clinics in your area, and think about whether this is a service you could provide • Revise your knowledge of novel oral anticoagulant drugs (NOACs), also known as direct oral anticoagulant drugs (DOACs), from the BNF section 2.8.2 ‘Oral anticoagulants’, and on the British Heart Foundation website at tinyurl.com/warfarin14 Evaluate Are you now confident in your knowledge of warfarin therapy? Could you give advice to patients about how warfarin may impact their day-to-day life?

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NOACs/DOACs available in the UK today – dabigatran, rivaroxaban, apixaban and edoxaban. One of the key differences between NOACs/DOACs and warfarin is that INR monitoring is not required with the former. This may be a more convenient option for patients who are unable to attend anticoagulant clinics. This lack of regular monitoring can have a downside, however, as it means patients have less contact with healthcare professionals, and so health issues may be missed.

3. Patients are usually advised to take their warfarin in the morning, after eating. True or false 4. Patients should not take a double dose of warfarin to make up for a missed dose. True or false 5. Monitored dosage systems are not generally recommended for anticoagulants, due to the frequent need to adjust doses. True or false

6. Warfarin doses should be reduced two weeks before having any vaccinations. True or false 7. Patients should have their INR checked and warfarin dose reduced before having any dental treatment. True or false 8. Pharmacists should always ask warfarin patients for their anticoagulant book when dispensing medication. True or false 9. The date of the most recent INR test, the INR result, and the current recommended dosage should be recorded on a patient’s medication record. True or false 10. Novel oral anticoagulant drugs, such as dabigatran, require blood monitoring every three months. True or false

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