Haemostasis Drugs Flashcards
Indications for anticoagulation? Therapeutic
Venous thrombosis
Atrial fibrillation - to reduce risk of embolic stroke
Mechanical prosthetic heart valve
Indications for anticoagulation? Preventative
(Thromboprophylaxis)
Following surgery
During pregnancy
Different types of heparin?
Long chains - unfractionated (IV administration, short half life)
Low molecular weight heparin (subcutaneous admission)
Actions of unfractionated heparin?
Enhancement of antithrombin
- inactivation of thrombin (hep binds AT + thrombin)
- inactivation of FXa (hep binds AT)
- (inactivation of FIXa, FXIa + FXIIa)
Action of LMWH?
Contains pentasaccharide sequence for binding AT
Predictable dose response in most cases so doesn’t require monitoring
UFH vs LMWH on APTT?
Both increase but LMWH does it predictably so doesn’t require monitoring, unlike UFH.
Warfarin MOA?
Vitamin K antagonist
Induces anti coagulated state slowly
Reversible (can administer Vitamin K to do it slowly, or rapidly by infusing coagulation factors - PCC or FFP)
Vitamin K effect?
Carboxylates glutamate (in FII, VII, IX + X)
Warfarin side effects?
Bleeding
Skin necrosis (severe protein C deficiency)
Purple toe syndrome
Chondrodysplasia punctata - is teratogenic in 1st trimester
What to use for warfarin monitoring?
International normalised ratio
Resistance to warfarin caused by?
Lack of compliance
Diet, vit K intake
Increased metabolism Cyt P450
Reduced binding
DOACs?
Work against factor Xa or IIa
Rapid
Fixed dose, no monitoring
DOACs vs Warfarin?
DOACs:
Rapid onset (Warfarin slow)
Fixed dosing (Warfarin variable)
No food effects or monitoring (Warfarin yes)
Few interactions (Warfarin many)
Some renal dependence (Warfarin none)
Choice of anticoagulant for venous thrombosis?
DOAC or LMWH for first few days, followed by DOAC or warfarin
Choice of anticoag for atrial fibrillation
DOAC or warfarin
