Warfarin

Question 1

Major bleeding (e.g., gastrointestinal bleeding, intracranial hemorrhage, or major trauma).

Answer 1

stop warfarin

give phytomenadione (vitamin K1) by slow intravenous injection; give dried prothrombin complex (factors II, VII, IX, and X); if dried prothrombin complex unavailable, fresh frozen plasma can be given but is less effective; recombinant factor VIIa is not recommended for emergency anticoagulation reversal

Question 2

Minor bleeding. INR >8

Answer 2

stop warfarin sodium; give phytomenadione (vitamin K1) by slow intravenous injection; repeat dose of phytomenadione if INR still too high after 24 hours; restart warfarin sodium when INR <5.0

Question 3

No bleeding. INR >8

Answer 3

stop warfarin sodium; give phytomenadione (vitamin K1) by mouth using the intravenous preparation orally [unlicensed use]; repeat dose of phytomenadione if INR still too high after 24 hours; restart warfarin when INR <5.0

Question 4

INR 5-8. No bleeding

Answer 4

withhold 1 or 2 doses of warfarin sodium and reduce subsequent maintenance dose

Question 5

INR 5-8. Minor bleeding

Answer 5

stop warfarin sodium; give phytomenadione (vitamin K1) by slow intravenous injection; restart warfarin sodium when INR <5.0

Question 6

Warfarin in pregnancy

Answer 6

Avoid in 1st trimester

Crosses the placenta causing congenital malformations, placenta, feats and neonatal haemorrhage

Question 7

Warfarin interactions

Answer 7

Increased risk of bleeding
Altered anticoagulant effect with pencillins
Increased anticoagulant effect with cranberry juice, metronidazole and tetracyclines

Question 8

Wafarin monitoring

Answer 8

Initially daily/alternate days. Then based on patient response to 12 weeks