Coumarins Flashcards
Give an example of a coumarin
Warfarin
What is the mechanism of action of warfarin?
It is a vitamin K antagonist, and interferes with the vitamin K cycle by inhibiting the enzyme vitamin K epoxide reductase. Vitamin K is needed to form clotting factors, hence the use of warfarin to reduce the likelihood of clot formation
What is the route of delivery of warfarin?
PO
What is warfarin available in?
Different colours, representing different strengths
How much warfarin in brown tablet?
1mg
How much warfarin in blue tablet?
3mg
What colours of warfarin are not used often?
White and pink (because they can get mixed up)
How much warfarin in white tablet?
0.5mg
How much warfarin in pink tablet?
5mg
What are the indications for warfarin?
- Prophylaxis and treatment of DVT and PE
- Prophylaxis of embolism in prosthetic valves
- Atrial fibrillation
What is the duration of treatment with warfarin in DVT/PE?
Variable, dependent on how many times patient has had DVT/PE and if it was spontaneous or provoked
What is the duration of treatment with warfarin in embolism in prosthetic valve?
Lifelong
What is the duration of treatment with warfarin with atrial fibrillation?
Lifelong
What are the contraindications to warfarin treatment?
- Haemorrhagic stroke
- Significant bleeding
What are the cautions in warfarin treatment?
- Bacterial endocarditis
- Conditions in which risk of bleeding is increased
- Up to 48 hours postpartum
- History of GI bleeding
- Hyperthyroidism or hypothyroidism
- Peptic ulcer
- Recent ischaemic stroke
- Recent surgery
- Uncontrolled hypertension
- Severe hepatic impairment
Is warfarin safe in pregnancy?
No, dangerous in 1st and 3rd trimester