Warfarin

Question 1

What contraindications are important to exclude before prescribing warfarin?

Answer 1

• Pregnancy
• Significant risk of major bleeding
• Active bleeding

Question 2

How would you describe the MOA of warfarin to a patient?

Answer 2

• Thins the blood to treat or prevent clots
• It does this by blocking vitamin K
• Vitamin K is used by the body to make proteins that cause blood to clot

Question 3

How should warfarin be taken?

Answer 3

• Once daily tablet (usually in the evening)
• 3 months for DVT
• 6 months of PE
• Lifelong for AF
• Dose changes takes 2-3 days to take effect

Question 4

What monitoring is required after prescribing warfarin?

Answer 4

• Start at 5mg each evening
• INR on days 3, 4, and 5 - warfarin dosing charts tell you how to adjust the dose
• Then regular INR checks by anticoagulation clinic (usually up to every 12 weeks) - regularity determined by INR stability

Question 5

What are the important side effects of warfarin that patients should be aware of?

Answer 5

• Bleeding - seek medical advice for significant head injury, prolonged nose bleeds, unusual headaches, blood in stool/urine/vomit, dark stools, unexplained or severe bruising
• Diarrhoea
• Rash
• Hair loss
• Nausea

Question 6

What should patients avoid when taking warfarin?

Answer 6

• Liver
• Spinach
• Cranberry juice
• Alcohol binges
• NSAIDs/aspirin