Anticoagulants, Antifibrinolytics and Anti-platelet agents Flashcards
Low molecular weight Heparin e.g Dalteparin: Mechanism of Action
Combine with antithrombin III and inhibit secondary haemostasis via relatively selective inactivation of factor Xa & thrombin by antithrombin, minimal effect on APTT
Low molecular weight Heparin e.g Dalteparin: Effects
decrease risk of DVT and PE
Low molecular weight Heparin e.g Dalteparin: Side Effects
Injection site heamatoma and pain
increased risk of bleeding
rarely hyperkalemia
Low molecular weight Heparin e.g Dalteparin: Dose
5,000 Units prophylactic dose SC
Theraputic dose according to weight
Low molecular weight Heparin e.g Dalteparin: Cautions
Haemorrhage, active major bleeding
Thrombocytopenia
Warfarin: Mechanism of Action
Antagonises the enzyme vitamin k epoxide reductase that is required for usual vitamin k metabolism. This inhibits carboxylation of clotting factors II, VII, IX and X rendering them inactive
Warfarin: Effects
More long term anticoagulation - AF, prosthetic heart valves, prophylaxis VTE
Delayed effect 48-72 hours
Warfarin: Side effects
haemorrhage
Warfarin: Cautions
Bleeding - should be stopped % days prior to surgery
Hemorrhagic stroke
Teratogenic
Warfarin: Dose
Daily maintenance dose is 3-9mg to target INR
INR 2.5 for
Treatment VTE or PE, AF cardioversion, dilated cardiomyopathy, mitral stenosis or regurgitation
INR 3.5 for
recurrent DVT or PE
avoid cranberry juice
DOAC (e.g. Apixiban, Riveroxiban, Dabigatrin): Mechanism of Action
Novel oral anticoagulants eg dabigatran (direct thrombin inhibitor) or rivaroxaban (Factor Xa inhibitor)
DOAC: Side Effects
Haemorrhage
DOAC: Cautions
No reversal agents available (except dabigatran)
Active bleeding
DOAC: Dose
apixiban 2.5 mg BD
Aspirin: Mechanism of Action
Blocks cyclooxygenase thereby blocking thromboxane A2 generation and inhibiting platelet aggregation
Aspirin: Effects/ Clinical Use
platelet inhibition - Useful in unstable angina and acute MI
Management of unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI),
Management of ST-segment elevation myocardial infarction (STEMI)
- cardiovascular disease secondary prevention
Aspirin: Side Effects
Nausea
Aspirin: Cautions
Gastrointestinal bleeding - history of ulcers
bleeding disorders
Aspirin: Dose
75 mg OD
Clopidogrel: Mechanism of Action
Covalently modify platelet ADP receptor, thereby preventing receptor signalling and irreversibly inhibiting ADP-dependent platelet activation
IHD: Acetylation of the platelet cyclooxygenase 1(COX 1) causing inhibition of platelet-dependent thromboxane.
Clopidogrel: Effects/ Clinical Use
Secondary prevention of atherosclerotic plaque in MI or stroke
Clopidogrel: Side Effects
N&V
Clopidogrel: Cautions
Atrial fibrillation
Heart failure
Active bleeding
Discontinue 7 days before elective surgery if antiplatelet effect not desirable; patients at risk of increased bleeding from trauma, surgery, or other pathological conditions
Clopidogrel: Dose
75mg OD, PO
What is the mechanism of Heparin and LMWHs?
Inactivation of thrombin, factor Xa inhibitor
What is the mechanism of Fondaparinux?
Selective factor Xa inhibitor
What is the mechanism of Dipyridamol?
anti-platelet
Phosphodiesterase inhibitor
What is the shared mechanism of Clopidogrel, Prasugrel, Ticagrelor?
Reversible/ irreversible P2Y12 receptor blockers
