Explanation of warfarin

Question 1

How does warfarin work?

Answer 1

• it thins the blood
• does this by blocking vit. K
• Vit. K is used by body to make proteins that cause the blood to clot

Question 2

How often do you take warfarin?

Answer 2

• once daily

- usually in the evening

Question 3

How do you take warfarin?

Answer 3

• orally in tablet form

- start at 5mg

Question 4

How long do I need to be on warfarin for?

Answer 4

• after DVT= 3mths
• after PE= 6mths
• for AF= lifelong

Question 5

How long until warfarin starts to work?

Answer 5

• 2-3 days

- may also start you on LMWH simultaneously if need immediate anti-coag. effect

Question 6

Do I need any tests while on warfarin?

Answer 6

• will need a blood test called an INR test regularly- at your GPs or local anti-coag. clinic.
• when you start will need a test on day 5 then on day 8 and they will adjust the dose depending on the result
• while they are stabilising the dose you may need a test 1/ wk
• once your results are stable you may only need INR test every 8-12 wks

Question 7

what are common SE w/ warfarin?

Answer 7

• bleeding in 1-2% people- tell Dr if bruises, dark stools, cuts taking longer to heal
• diarrhoea
• rash
• hair loss
• nausea

Question 8

What are potential drug interactions with warfarin?

Answer 8

• CYP450 inhibs./ inducers

- steroids

Question 9

Are there any CI for warfarin?

Answer 9

• pregnancy
• haemorrhagic stroke
• signif. bleeding

cautions
- pt. @ high risk of falls

Question 10

Supplementary advice for warfarin

Answer 10

• avoid liver, spinach, cranberry juice, grapefruit, alcohol binges
• no NSAIDs/ aspirin
• given an anti-coag. book