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53 Cards in this Set
- Front
- Back
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What are some types of anti-platlet drugs?
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- cyclo-oxygenase inhibitors
- phosphodiesterase inhobitor - ADP receptor pathway inhibitors - GPIIb/IIIa receptor antagonists |
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What class of drug are these?
- Abciximab - Eptifibatide |
GPIIb/IIIa receptor antagonists
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What class of drug are these?
- Clopidogrel - ticlopidine |
ADP receptor antagonist
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What class of drug are these?
- dipyridamole |
phosphodiesterase inhibitor
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Why is the effect of aspirin irreversible?
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platelets lack the ability to synthesize new enzyme cyclo-oxygenase
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What is the mechanism of aspirin?
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- irreversible inhibition of cyclo-oxygenase
- decrease TRX release from granules |
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Why use low dose aspirin (instead of high dose) to prevent clot?
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low dose aspirin inhibit COX1 in platelets: no TRX synthesis.
high dose aspirin also inhibit COX2 in endithelial cells: no PGI-2(anti-aggregatory). |
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Anti-platelet agents are useful in ____.
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preventing cerebral and myocardial ischemia.
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Decrease in platelet cAMP is ____.
A. pro-aggregatory B. Anti-aggregatory |
A.
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ADP receptor agonist ____ (stimulate/inhibit) adenylate cyclase and ____ (increase/decrease) cAMP.
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ADP receptor agonist inhibit adenylate cyclase and decrease cAMP.
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How does clopidogrel(Plavix) work?
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ADP receptor antagonist -> increase cAMP -> anti-aggregatory
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How does dipyrimadole work?
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1) phosphodiesterase inhibitor -> raise post-receptor cAMP
2) act on vascular smooth muscle to vasodilate |
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Name the three drugs that raises cAMP.
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- clopidogrel (Plavix)
- ticlopidine - dipyrimadole |
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What is the indication for Ticlopidine.
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To prevent 2nd stroke in patients who cannot tolerate other drugs.
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What is the drawback of Ticlopidine.
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May cause aplastic anemia
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Which of the following has a higher risk for GI bleed?
A. Aspirin B. Clopidogrel |
A.
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Which anti-platelet drug can be combined with aspirin or warfarin.
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dipyrimadole
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What are the four types of anticoagulants?
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1. immediate acting: heparin
2. delayed acting: warfarin 3. direct thrombin inhibitor 4. activated protein C |
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What is the major toxicity of anticoagulants?
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bleeding
*others: - antoantibodies to heparin - rare idiosyncratic microvascular clotting with warfarin (due to genetic protein C or S defiency). |
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What some actions of thrombin?
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- activates factor V, VII, VIII, XI, XIII.
- convert fibrinogen to fibrin - activate platelets and endothelial cells - stimulate the release of PGI2, NO, and tPA from intact endothelial cells near the site of injury. |
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What is this?
heterogenous group of mixed polysaccharides of variable length and MW |
heparin
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Which part of heparin recognizes, binds, and activates antithrombinIII by conformational change?
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panta-saccharide unit
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What is the antedote of heparin? and how does it work?
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Protamine:
highly positively charged protamine bind to negatively charged heparin. |
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Which type of heparin promotes binding of thrombin, factor IXa, Xa, XIa, XIIa to antithrombinIII?
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unfractionated heparin
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Which type of heparin can be administered IM?
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Low-MW heparin.
IM High MW heparin will cause hematoma. |
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Which is more selective for factor X?
A. low MW heparin B. high MW heparin |
A.
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What is a synthetic analogue of heparin that is used specifically for DVT?
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Fondaparinux
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Which causes less antibody formation against paltelets?
A. Low-MW heparin B. High-MW heparin |
A.
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Which is type of heparin binds to antithrombin which can inactivate factor Xa, but but able to inactivate thrombin?
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low MW heparin
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Which drug inactivate factor Xa specifically?
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Fondaparinux
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Which drug inactivates thrombine without action of antithrombinIII?
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Hirudin
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What is the polymer length for low and high MW heparin?
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low MW heparin: 1-5 kD
high MW heparin: 5-30 kD |
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Which is more potent at low doses?
A. low MW heparin B. high MW heparin |
A.
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How does deCon work as a rodenticide?
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internal bleeding
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Which anticoagulant is used for atrial fibrillation?
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warfarin
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What is the mechanism of warfarin?
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inhibit epoxide reductase which converts inactive VitK to the active reduced form.
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How are factors II, VII, IX, and X acitvated?
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carboxylation which is assited by VitK.
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Which of the following is affected first by warfarin?
A. Factor II B. Factor VII C. Factor IX D. Factor X E. PC |
C. Because factor VII has the shortest t1/2 (6hrs).
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Where common areas that are likely to bleed after taking warfarin?
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- sublingual region
- GI tract - skin - lung |
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Who are warfarin contraindicated for?
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- Elderly with history of falling -> cerebral hemorrhage.
- pregnant women: teratogen -> hypoplastic nose, flat face, low nasal bridge, altered skeletal calcification and bone growth. |
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What are some drug interaction that decreases warfarin effect in patients system?
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-cholestyramine: inhibit warfarin absorption
- barbituates: induce P450 - oral VitK: bypass the target enzyme blocked by warfarin *Warfarin in metabolized by P450 |
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What are some drug interaction that increases warfarin effect in patients system?
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- chloral hydrate: displace warfarin from plasma protein
- chloramphenicol: inhibit enzyme elimination in liver - broad spectrum antibiotics: decrease availability in GI tract - anabolic steroid: inhibit clotting factor liver synthesis and increase degradation |
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What is the antedote for warfarin?
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carboxylated clotting fators (frozen plasma)
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What species produces direct thrombin inhibitor?
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- leech: hirudin
- mosquito |
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Which drug produce a close fit with thrombin and directly inhibits it?
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hirudin: van der waals force
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What is the indication for hirudin?
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For patients who cannot take heparin.
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What is the mechanism of protein C?
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- inhibits factor V and VIII
- decreases circulating levels of plasminogen activator inhibitor - inhibits TNF from monocytes |
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Which drug is approved for septic shock?
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activated protein C which inhibits TNF-alpha.
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How is plasminogen activated to plasmin?
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by t-PA or u-PA
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Plasmin is normally inhibited by ___.
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alpha2-antiplasmin
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Which drug is indicated in ischemic stroke, but contraindicated for hemorrhagic stroke?
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t-PA
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What class of enzyme are streptokinase and urokinase?
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proteases.
- activational conformational change in plasminogen->chain reaction - immunogenic - non-specific system fibrinolysis and pathogenic hemorrhage |
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What are some indications for clot busters?
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Patients with chest pain consistent with diagnosis of acute MI and at lease 0.1mm of ST-segment elevation in at least two contiguous ECG leads.
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