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24 Cards in this Set
- Front
- Back
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how does AT-III inhibit coagulation? what does heparin do to this?
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- inhibits thrombin (IIa) & FIX, X, XI
- heparin potentiates AT-III |
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how do you administer unfractionated heparin?
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- need to do IV b/c low bioavailability, short half-life
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what form of herparin do you get HIT from? what is HIT? how do you treat it?
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- from UFH
- HIT = herparin induced thrombocytopenia --> immune mediated rx --> IgG against heparin-PF4 --> antibody complexes activate endothelial cells - despite low platelet count overall concern is clotting - treat it by discontinuing all heparin exposure, switch to DTI (argatroban) then bridge to warfarin |
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what is enoxaparin (levonox)? what does it work on?
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- LWMH
- inhibits Xa >> IIa (thrombin) |
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what is fondaparinux? what does it work on?
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- synthetic pentasaccharide of heparin --> usedd less frequently because so expensive
- PURE Xa inhibitor, but still needs AT-III to work |
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how do you monitor UFH vs LWMH vs Fodaparinux?
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- UFH need to monitor PTT
- for LWMH & fodaparinum need to directly assay Xa because greater effects there |
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what is the antidote for heparin overdose?
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- protamine sulphate neutralizes UFH & 80% of LWMH
- no antidote for fondaparinux |
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when are direct thrombin inhibitors used?
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- indiccated for treatment of HIT
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what is the different between argatroban vs lepiurdin?
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- both are DTIs
- argatroban: hepatic clerance - lepirudin: renal clearance |
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how does dabigatran differn from agratobran & lepirudin?
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- dabigatran is an oral DTI
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how do direct thrombin inhibitors (DTI) work?
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- inactivate thrombin, but AT-III independent
- not neutralized by PF4 - aka no thrombocytopenia/HIT |
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are their antidotes for DTI?
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- no antidotes for DTIs
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how is warfarin taken? what is the half-life?
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- taken orally
- half-life is 36-42 hours |
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what is the MOA of warfarin?
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- inhibits vit K epoxide reductase & vit K reductase --> interfere w/ recycling of vit K = no II, VII, IX, X
- need vit K for gamma carboxylation adding Gla --> anchor to phospholipids via Ca so they can participate in thrombosis |
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what can affect warfarin MOA?
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- hepatic dysfunciton (b/c relies on CYT P450 system), thyroid, fever, co-morbidities, nutritional status
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how do you monitor warfarin? what is the INR?
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- measure it w/ PT b/c FVII falls the most with warfarin therapy
- INR you need to standardize PT time w/ thromboplastin reagant --> given (international sensitivity index) to standardize it against standard thromboplastin (how sensitive is agent to FVII) |
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what is the formula for the INR? what is the therapeutic range?
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- PT ratio = pt PT/conrol PT --> INR = (PT ratio)^ISI
- therapeutic range is between 2-3 |
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what is the heparin bridge?
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- warfarin decreases protein C & S so it is actually pro-coagulant at first
- do heparin bridge for 5 days then have 2 consecutive days of INR therapeutic levels |
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what are some side effects of warfarin? why do you avoid in pregnancy?
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- most common side effect of all anticoagulants is bleeding
- warfarin induced skin necrosis in pts with protein C deficiency b/c initial microthombosis - avoid in pregnancy b/c teratogenic |
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what is dabigatran? rivaoxaban?
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- dabigatran is new thrombin inhibitor
- rivaoxaban is Xa inhibitor - both have no monitoring & no antidote |
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how do thrombolytic agents work?
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- convert plasminogen --> plasmin which breaks down fibrin clot
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how fast does recombinant tPA work?
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- binds plasminogen bound to fibrin to avoid systemic lysis
- cleared w/in 4-8 minutes |
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how do clopidogrel & prasugrel work?
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- ADP inhibitors
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how does abciximab work?
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- GP IIb/III antagnoist
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