Patient on anti-coagulant therapy Flashcards
what are the 2 main types of oral anticoagulants?
- Vitamin K antagonists
- Direct oral anticoagulants (DOACs)
what is the purpose of anticoagulation?
to prevent thrombus formation in the veins where blood flow is slow
- thrombus consists of a fibrin web, platelets and RBCs
what is an example of a vitamin K antagonist?
warfarin
- inhibits vitamin K dependent clotting factors eg X, IX, VII and II and protein C and S
what are examples of DOACS?
- apixaban
- dabigatran
- edoxaban
- rivaroxaban
what is the mechanism of action of apixaban, edoxaban and rivaroxaban?
reversible inhibition of factor Xa
- prevents thrombin generation and thrombus formation
what is the mechanism of action of dabigatran?
reversible inhibition of free thrombin, fibrin-bound thrombin and thrombin-induced platelet aggregation
what should be measured prior to starting warfarin?
baseline prothrombin
what is warfarin licensed for?
- Prophylaxis of embolism in rheumatic fever and AF
- Prophylaxis in prosthetic heart valves
- prophylaxis and treatment of DVT, PEs and TIAs
when are DOACs preferred over warfarin?
- non-valvular AF
AND
- HF, HTN, previous stroke/TIA, >75yrs or DM
which DOACS can be used for PE and DVT?
ALL
- apixaban
- dabigatran
- edoxaban
- rivaroxaban
which DOACs can be used for VTE after hip/knee replacement?
- apixaban
- dabigatran
- rivaroxaban
which DOACs can be used for prophylaxis after ACS or PAD?
rivaroxaban
what are the contraindications of warfarin?
- haemorrhagic stroke
- significant bleeding
- severe hepatic impairment
- <72hrs post major surgery
- <48hrs postpartum
- drugs that interact with warfarin
what can increase action of warfarin and therefore require dose decrease?
- weight loss
- acute illness
- smoking cessation
what can decrease action of warfarin and therefore require dose increase?
- weight gain
- diarrhoea
- vomiting
what is the main adverse effect of all anticoagulants?
BLEEDING!!!
what are the side effects of warfarin?
- bleeding
- teratogenic (Teratogens are substances that cause congenital disorders in a developing embryo or fetus.)
- skin necrosis (decreased protein C > procoagulant state)
what is important to inform patients taking rivaroxaban?
must be taken with food
what are the contraindications of rivaroxaban?
- severe renal impairment
- active/risk of bleeding
- anti-phospholipid syndrome
- prosthetic valves
- liver disease affecting coagulopathy
- previous stroke/TIA
what are the side effects of rivaroxaban?
- bleeding
- GI effects
what is the reversal agent for warfarin?
- IV vit K 5mg
- prothrombin complex concentrate
what is the reversal agent for rivaroxaban?
andexanet alfa
- recombinant form of human factor Xa protein
how is warfarin monitored?
INR
- therapeutic range between 2-3
- variations within 0.5 units of target are ok
