Switching between anticoagulants
The National Institute for Health and Care Excellence (NICE) guideline5 on anticoagulation in AF recommends the use of either NOACs or vitamin K antagonists. It is, however, patient preference, cognitive function, co-morbidities and liable INR that can determine choice of anticoagulant. These parameters can change throughout a patient’s clinical condition, which may require an anticoagulation switch.
Instances where vitamin K antagonists may need to be switched to a NOAC can be determined by time in therapeutic range (TTR). NICE highlights the following factors to reassess therapy and possibly to switch to a NOAC:
- Two INR values higher than 5 or one INR value higher than 8 within the past six months
- Two INR values less than 1.5 within the past six months
- TTR less than 65%.
On the flip side, patients well-established on a NOAC, may need to switch to a vitamin K antagonist, for example, if they are having a mechanical valve replacement since NOACs are only being licensed for non-valvular AF.
The dosing recommendations on switching can be found in the summary of product characteristics (SPCs).
Role of the community pharmacist in optimising this patient’s care
Patients have regular access to community pharmacists, who can add to the care of a patient medicated with anticoagulation and antiplatelet therapy. Anticoagulants are one of the classes of medicines most frequently identified as causing preventable harm and admission to hospital.
Following the National Patient Safety Agency guidance6 issued in March 2007 on the safe use of anticoagulant therapy, pharmacists are in a prime position to provide both medication and disease-state counselling. The guidance recommends that patients receive appropriate information throughout the course of their treatment, and that their INRs (for warfarin) are monitored regularly, to ensure they are at a safe level (see figure 1), before repeat prescriptions for oral anticoagulation are dispensed.
The guidance also suggests that pharmacists dispensing clinically significant interacting medicines, such as antibiotics, or another medication that may increase the risk of bleeding (e.g. selective serotonin re-uptake inhibitors, or non-steroidal anti-inflammatory drugs (NSAIDs)), should take additional safety precautions. These include:
- informing the anticoagulant service that an interacting medicine has been prescribed
- ensuring additional INR blood tests have been arranged to monitor any changes.
More recently, the New Medicines Service (NMS)7 has been introduced as an advanced service to the community pharmacy contract. The service provides support for people with long-term conditions newly prescribed a medicine, helping to improve medicine adherence. The optimal use of appropriately prescribed medicines is vital to the self-management of most long-term conditions, but reviews conducted across disease states are consistent in estimating that between 30–50% of prescribed medicines are not taken as recommended. This represents a failure to translate the technological benefits of new medicines into health gain for individuals. Sub-optimal medicine use can lead to inadequate management of long-term conditions, and a cost to the patient, the NHS, and to society.
The NMS currently focuses on specific patient groups and conditions, including antiplatelet and anticoagulant therapy.
The service is such that all patients newly prescribed an anticoagulant, for example, will be eligible to receive it. The NMS provides an interview schedule to facilitate discussions between pharmacist and patient. These include:
- Have you had a chance to start taking your new medicine yet?
- How are you getting on with it?
- Are you having any problems with your new medicine, or concerns about taking it?
If you are a hospital-based pharmacist or prescriber, consider referral to the new medicine service. This will provide the reassurance that any information provided to the patient is reinforced by community pharmacy colleagues, and that any problems patients experience will be addressed and discussed.
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References
1. Commissioning effective anticoagulation services for the future: a resource pack for commissioners. Anticoagulation Europe 2013. Available from http://anticoagulationeurope.org/publications (accessed 20/02/13)1. Commissioning effective anticoagulation services for the future: a resource pack for commissioners. Anticoagulation Europe 2013. Available from http://anticoagulationeurope.org/publications (accessed 20/02/13)
2. Dorian P, et al. The Impairment of health related quality of life in patients with intermittent AF; implications of the assessment of investigational therapy. J Am Coll Cardiol 2000;36:1303–9. http://dx.doi.org/10.1016/S0735-1097(00)00886-X
3. Summary of product characteristics for apixaban, rivaroxaban, dabigatran, and warfarin. Electronic Medicines Compendium 2012. Available from http://emc.medicines.org.uk/ (accessed 20/02/13)
4. Summary of product characteristics for edoxaban. Electronic Medicines Compendium 2015. Available from http://emc.medicines.org.uk/ (accessed 09/08/15)
5. National Institute for Health and Care Excellence. Atrial fibrillation: the management of atrial fibrillation. Clinical guideline 180. Issued June 2014, last modified: August 2014. https://www.nice.org.uk/guidance/cg180/resources/guidance-atrial-fibrillation-the-management-of-atrial-fibrillation-pdf
6. National Patient Safety Agency. Patient safety alert: actions that can make anticoagulant therapy safer(Alert 18), 2007. Available from http://www.nrls.npsa.nhs.uk/resources/?entryid45=59814 (accessed 20th February 2013)
7. Outline service specification – New Medicine Service. Pharmaceutical Services Negotiating Committee 2011. Available from http://www.psnc.org.uk/pages/nms.html (accessed 20/02/13)
Further reading
Hicks T, Stewart F, Eisinga A. NOACs versus warfarin for stroke prevention in patients with AF: a systematic review and meta-analysis. Open Heart 2016;3:e000279. http://dx.doi.org/10.1136/openhrt-2015-000279
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