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60 CPD ACTIVITY FROM PAGE 59 Patient resources: • An ‘anticoagulant booklet’ or the NPS MedicineWise Warfarin Dose Tracker at: resources.amh.net.au/public/warfarin-dose-tracker.pdf • NPS MedicineWise warfarin information: nps.org.au/consumers/warfarin Key points • Warfarin is indicated for stroke prevention in patients with AF, thrombus formation in those with prosthetic heart valves, and prevention and treatment of venous thromboembolism. • Older age alone is not a barrier to warfarin use in those with AF. Bleeding risks should be managed by addressing risk factors and dose adjustment guided by INR. • Pharmacists play an integral role in warfarin management, including INR monitoring and patient education to optimise warfarin use. Conclusion Although anticoagulation with non-vitamin K oral antagonists is increasingly preferred because routine laboratory monitoring is not required, warfarin still has an important place in older people with multiple morbidities, concurrent medicines, significant renal or hepatic impairment and in those who are already well controlled with adherent INR testing. Pharmacists can help promote the safe use of warfarin to improve the balance of benefit versus bleeding risk References 1. PirmohamedM.‘Warfarin:almost60yearsoldandstillcausingproblems’. BJCP 2006; 62(5):509-11. 2. ‘Optimal use of warfarin’. AMH Aged Care Companion. Adelaide: Australian Medicines Handbook; 2020. 3. The warfarin dilemma. In: BPJ 31:22-29. 2010. At: bpac.org.nz/bpj/2010/october/warfarin.aspx 4. eTG complete. Melbourne: Therapeutic Guidelines; 2021. 5. Rossi S, ed. Australian Medicines Handbook. Adelaide: Australian Medicines Handbook; 2021. 6. Harter K, Levine M, Henderson S. ‘Anticoagulation drug therapy: A review’. West J Emerg Med, 2015; 16 (1): 11-17. 7. ChinP,DoogueM.‘Long-termprescribingofneworalanticoagulants’. Aust Prescr, 2016; 39: 200-4. 8. Xarelto product information. In: MIMs cloud. Sydney: MIMS Australia; 2020. 9. Eliquis product information. In: MIMs cloud. Sydney: MIMS Australia; 2020. 10. Apixaban (Eliquis) for stroke prevention in non-valvular atrial fibrillation. NPS MedicineWise RADAR. 2013. At: nps.org.au/radar/articles/apixaban-eliquis-for-stroke- prevention-in-non-valvular-atrial-fibrillation 11. Australian Government Department of Veterans’ Affairs: Veterans’ Mates. Therapeutic Brief 37: The oral anticoagulant dilemma. 2013. At: veteransmates.net.au/ topic-37-therapeutic-brief 12. Stevens H, Tran H and Gibbs H. ‘Venous thromboembolism: Current management’. Aust Prescr, 2019; 42: 123-6. 13. McCallum C, Raja F, Pathak R. ‘Atrial fibrillation: An update on management’. Aust Prescr, 2019; 42: 186-91. 14. Tran H, Chunilal S, Harper P, et al. ‘An update of consensus guidelines for warfarin reversal’. Med J Aust, 2013; 198 (4): 198-9. 15. Shendre A, Parmar G, Dillon C, et al. ‘Influence of age on warfarin dose, anticoagulant control, and risk of hemorrhage’. Pharmacotherapy, 2018; 38 (6): 588-96. 16. Australian Government Department of Health and Ageing Therapeutic Goods Administration: Medicines Safety Update No. 2; 2010. At: tga.gov.au/publication-issue/medicines-safety-update-no2-2010 17. Clinical Excellence Commission, 2017, Non-vitamin K Antagonist Oral Anticoagulant (NOAC) Guidelines. At: www.cec.health.nsw.gov.au/ Accreditation Number: A2103RP3 (exp:21/03/2023) This activity has been accredited for 1 hour of Group One CPD (or 1 CPD credit) suitable for inclusion in an individual pharmacist’s CPD plan, which may be converted to 1 hour of Group Two CPD (or 2 CPD credits) upon successful completion of the associated assessment activity. 1. Regarding the pharmacodynamics of oral anticoagulant agents, which statement is CORRECT? A) Warfarin inhibits the synthesis of clotting factors II, VII, IX and X. B) Rivaroxaban directly affects platelet aggregation. C) Warfarin’s bioavailability is about 80 per cent. D) Oral non-vitamin K antagonists have longer half-lives than warfarin. 2. Which of the following statements about the clinical uses of warfarin is CORRECT? A) Warfarin is indicated for prevention of venous thromboembolism (VTE) following elective hip or knee replacement. B) Monotherapy with warfarin is the preferred option over a NOAC for most adults with acute VTE. C) Warfarin is indicated for prevention of stroke in those with increased embolic risk and previous MI. D) A patient with atrial fibrillation (AF) and a CHA2DS2-VA score of 1 should not be recommended for treatment with warfarin or another oral anticoagulant. 3. Your local GP has asked you for advice on initiating warfarin in Mr MK with paroxysmal AF. Mr MK is 72 years old and takes metformin for type 2 diabetes. He also takes a daily coenzyme Q10 supplement. He lives alone and socialises at the pub for some beers and a meal three times a week. Which advice is MOST APPROPRIATE? A) Considering his CHA2DS2-VA score and that AF is not chronic, aspirin would be a better choice than warfarin. B) Before starting, he should have a baseline INR level taken and be advised to cease coenzyme Q10 and not to drink alcohol excessively. C) A usual regimen would start with a 10mg dose of warfarin for the first three days before checking the INR. D) The INR should be checked every three days until it is stable in the target range. 4. As older patients with AF are at greater risk of both stroke and intracranial bleed, which of the following statements is CORRECT? A) A 75-year-old woman with AF and renal impairment has a HAS-BLED score of two, so warfarin is contraindicated. B) Older patients are more sensitive to warfarin anticoagulation so require a higher dose. C) The relative risk of bleeding increases with age, despite older patients being more consistently in the target INR range. D) The bleeding risk associated with warfarin is highest in the first three weeks of therapy, before reducing. 5. When a pharmacist counsels a patient about warfarin, which advice is MOST APPROPRIATE? A) Risk of bleeding is the most important factor in deciding whether warfarin is warranted in older people with AF. B) If the patient becomes unwell with a vomiting bug, they can delay the INR test until they feel better. C) Cranberry juice can be taken safely concurrently with warfarin. D) There is individual variability in response to warfarin and different effects of diet and other drugs, so regular INR testing is a most important check to optimise safety of therapy. Warfarin use in older people: an overview 2 CPD CREDITS RETAIL PHARMACY • MAR 2021