Anti-platelets + Anti-coagulants Flashcards
Which type of drug is used to treat arterial thrombosis?
Anti platelets e.g. aspirin
Which type of drug is used to treat venous thrombosis?
Anti-coagulants e.g. warfarin, heparin, DOACs
How does aspirin work?
Inhibits cyclo-oxygenase which is necessary to produce thromboxane A2 (a platelet agonist released from granules on activation)
What are the side effects of aspirin?
- bleeding
- blocks production of prostaglandins:
- GI ulceration
- bronchospasm
Name 4 other anti-platelet drugs other than aspirin?
Clopidogrel + prasugrel
Dipyridamole
Abciximab
How do clopidogrel + prasugrel work?
ADP receptor antagonists
How does dipyridamole work?
Phosphodiesterase inhibitor
- reduces production of cAMP which is a second messenger in platelet activation
How does abciximab work?
GP IIb/IIIa inhibitor
–> inhibits aggregation of platelets
How long do the effects of anti-platelets last after stopping taking them?
About 7-10 days (lifespan of platelets)
What can do does to reverse anti-platelet function in severe bleeding?
Platelet transfusion
What are the indications for anticoagulant drugs?
Venous thrombosis
Atrial fibrillation
Which drugs are anticoagulants?
Heparin
Warfarin
Direct oral anticoagulants
How does heparin work?
Potentiates antithrombin
How is heparin given?
Parenteral –> SC or IV
What are the type different types of heparin?
Unfractionated
LMWH
Which monitoring is required for patients taking heparin?
Unfractionated –> APTT
LMWH –> can monitor anti-Xa assay but not usually required
FBC
What are the complications of heparin?
Bleeding
Heparin induced thrombocytopenia (with thrombosis) - HITT
–> monitor FBC
Osteoporosis with long term use
How is heparin reversed if necessary?
Stop the heparin (short half life)
If very severe bleeding:
–> protamine sulphate
- reverses antithrombin effect
How does warfarin work?
Inhibits vitamin K
Which factors are affected by inhibition of vitamin K?
2 (prothrombin), 7, 9, 10
How is warfarin monitored?
INR - calculated from PT
What are the options for management of bleeding in a patient on warfarin?
Oral vitamin K Clotting factors (factor concentrates)
–> depends of severity of bleeding + INR
How long does oral vitamin K take to work?
6 hours
How long do clotting factors take to work?
Immediate
Give some examples of the new oral anticoagulant drugs and how they work
Direct thrombin inhibitors –> dabigatran
Direct Xa inhibitors –> edoxaban, rivaroxaban, apixaban
What are the advantages of DOACs?
Oral
No monitoring required
Less drug interactions
Recently developed specific antidotes
