Warfarin

Question 1

ATHLETICS

Answer 1

Action
Timing
How to take
Length of treatment
Effects - time to take effect
Tests required
Important side effects
Complications and Contraindications
Supplementary advice

Question 2

Action

Answer 2

Thins the blood.

It does this by blocking vitamin K – the vitamin used by the body to make proteins that cause the blood to clot.

Question 3

Timing

Answer 3

Once daily (usually in the evening)

Question 4

How to take?

Answer 4

Tablet

Question 5

Length of treatment?

Answer 5

3 months for provoked PE/DVT
longer if provoked
Lifelong for AF

Question 6

Effect - time before taking effect?

Answer 6

2-3 days

Question 7

Tests?

Answer 7

Start 5mg for 4 days then test INR on day 5 and 8, adjusting dose accordingly.
Started concomitantly with LMWH if immediate effect is required.
Then, regular INR checks by anti- coagulation clinic – regularity determined by INR stability

Question 8

Important side effects

Answer 8

Bleeding (1-2%) – tell doctor if any unusual bleeding e.g. bruises, dark stools, cuts take longer to heal.
Also diarrhoea, rash, hair loss, nausea.

Many drug interactions:
NSAIDs/aspirinq

Mainly with cytocrome P450 inhibitors/inducers (see notes on drug interactions), steroids

Question 9

Contraindications?

Answer 9

Pregnancy
Haemorrhagic stroke
Significant bleeding
High risk of falls

Question 10

Supplementary advice

Answer 10

Avoid liver, spinach, cranberry juice, alcohol binges
No NSAIDs/ aspirin
Given anticoagulant book