S18C234 - Anticoagulants, Antiplatelets, Fibrinolytics Flashcards
1
Q
Warfarin
A
- 1/2 life 36h
- blocks activation of vit K therefore interferes with factors II, VII, IX, X and blocks synthesis of proteins C and S ( antithrombotic factors)
- ie. warfarin has antithrombotic and thrombotic effect but overwhelming effect is AC
- target for prosthetic heart valve and for antiphospholipid antibody syndrome is 2.5-3.5
- skin necrosis develops 3-8d after starting warfarin, treat by d/c warfarin, giving vit k and providing a parenteral AC
2
Q
Reversal of warfarin and high INR
A
- options: Stop warfarin, give vit k, give FFP or PCC or factor VIIa
- asymptomatic INR 5-9: stop warfarin, give vit K 1-2.5mg PO (oral decrease INR faster - 16h- than SC vit K)
- asymptomatic INR >9, vit K 2.5-5mg PO and hold warfarin
- elevated INR and serious bleeding present: 10mg vit K slow IV push (rpt in 12h if inr stil lhigh), 10-15ml/kg FFP (4 units)
3
Q
IV Vit K: risk
A
- risk of anaphylaxis rxn
- only give IV if life-threatening bleed or inr >20 or symptomatic pts who have been poisoned
4
Q
Rivaroxaban
A
- direct Factor Xa inhibitor
- OD dosing
- 10mg OD for VTE prophylaxis
5
Q
Heparin
A
- UFH
- binds to antithrombin
- interferes with intrinsic and extrinsic pathways (Xa, IXa, XIa, XIIa, thrombin)
- effects mostly from Xa inhibition
- 1/2 life is 30-150min
- do not use SC UFH for acute VTE, but may be used prophylactically
- neither UFH or LMWH cross the placenta
- AC effect can be monitored with aPTT with therapeutic range being 1.5-2.5 aPTT times the normal value (normal = 25-40 sec)
6
Q
LMWH
A
- advantages of UFH: quick and predictable absorption, more reliable AC, does not need to be monitored, decreased risk of HIT, can be given as outpatient therapy, greater anti-factor Xa activity, less anti-factor IIa activity
- caution in pts with renal dz
- indications: DVT, PE, ACS
7
Q
Fondaparinux
A
- indications: VTE prophylaxis and tx of DVT/PE
- binds AT and enhances its affinity for Factor Xa
8
Q
UFH reversal
A
- protamine
- give it slowly IV over 1-3min, NMT 50mg in a 10min period
- risk of anaphylaxis therefore only use if major bleeding
9
Q
UFH HIT
A
- stop all heparin products
- administer fondaparinus
- do not give warfarin
10
Q
Argatroban
A
-hirudin: direct thrombin inhibitors, do not require AT as a cofactor
11
Q
Antiplatelets: Aspirin
A
- irreversilby blocks cyclooxygenase
- antithrombotic
- peak concn in 15-20mins, 1/2life 4h
- irreversible, lasts for lifespan of platelet (7d)
- dose 162-325mg
12
Q
Clopidogrel
A
- inhibit platelet activation by inhibiting the ADP receptor
- 600mg gives full antiplatelet effect by 2h and lasts 48h
- give for ACS whether pt going for lysis or PCI
- some pts will have a diminished antiplatetlet response
- omeprazole decreases clopidogrel activity
13
Q
Fibrinolytics:
A
convert plasminogen to plasmin which then enzymatically breaks apart the fibrin componenet of thrombi
14
Q
Lytics: alteplase
A
- tissue plasminogen activator (TPA)
- 1/2 life is
15
Q
Lytics: tenecteplase
A
- similar to alteplase
- longer 1/2 life = 20mins
- single wt based bolus over 5-10sec
- no mortality benefit in STEMI over alteplase
