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20 Cards in this Set
- Front
- Back
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three heparin classes/drug names
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1. UH (unfractionated heparin) - MW = 15000 avg
2. LMWH - Enoxaparin. MW = 5000 avg 3. Pentasaccharide - Fondaparinux. |
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heparin MOA
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join AntiThrombin III and Thrombin to inactivate thrombin. also inactivates F-Xa. Need UH or LMWH to join Thrombin<->ATIII, so Fonaparinux doesn't inactivate Thrombin, but it does inactivate F-Xa.
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benefit of LMWH over UH?
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LMWH has less non-specific binding of arbitrary cells/proteins.
greater bioavailability more effective regarding DVT and MI self administration OK longer 1/2 life more predictable response more bioavailability |
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how are heparins administered? do heparins cross placenta? pass into mom's milk?
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SC (highly charged - not oral!) or IV for lots of UH
NO NO |
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how is UH monitored?
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aPTT until time is 2x normal
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how are LMWH and Fondaparinux monitored?
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usually they are not monitored. if necessary: minimal aPTT change, thus use the "antifactor Xa Activity" assay, which takes plasma + Factor Xa + chromogenic substate + ATIII. less color = more [heparin]
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how does SC bioavailability differ among the heparins? what affects this bioavailability?
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Fondaparinux > LMWH >> UH.
affected by their uptake by Macrophages. process is 0 order for UH. |
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Longest 1/2 life among heparins?
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Fondaparinux, 20 hours.
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Protamine Sulfate - MOA. with which type of heparins is it most efficient?
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it's highly (+), so it binds and inactivates heparin. it's less effective with the LMWH (and Fondaparinux?)
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aside from Hemorrhage, what is a major side effect of heparin?
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Heparin Induced Thrombocytopenia. type 1 is mild - activates platelets -> thrombocytopenia.
type 2 - serious - along with Thrombosis Syndrome (Thus HITTS) - Ab's (eventually on platelet surface) form against PF4-Heparin and activates platelets -> thrombocytopenia can also occur on endothelium, leading to TF exposure and thus Clotting |
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what is the mechanism of hirudin/lepirudin?
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direct inhibitor of free and bound Thrombin, whereas heparin only inhibits free Thrombin
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what is warfarin's MOA? list all the coagulation factors it affects
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inhibits gamma-carboxylation of coag factors via blocking vitamin K cycle
affects 2, 7, 9, 10 and Protein C and S |
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how can warfarin's effects be reversed?
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giving vitamin K. however, it will take 24 hours to reverse effects.
if ER, can give FFP |
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what drugs can lead to faster warfarin metabolism? slower?
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faster: barbiturates, rifampin, carbamazepine
slower: bactrim, metronidazole, (more listed p171 notes) |
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when is warfarin contraindicated?
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1st trimester pregnancy
liver/renal disease bleeders |
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fibrinolytics indications:
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PE, DVT, MI, and ischemic stroke
(not hemorrhagic stroke!) -best if w/in 4 hours |
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fibrinolytics MOA:
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activate plasminogen to plasmin.
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side effect of fibrinolytics
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1. intracranial bleeding (very bad)
2. GI bleeding |
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treatment of hemorrhage (after induced by fibrinolytics)
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aminocaproic acid (EACA)
FFP |
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name some fibrinolytic drugs
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streptokinase
alteplase urokinase anistreplase |
