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20 Cards in this Set
- Front
- Back
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Give 4 examples of anticoagulant drugs |
warfarin heparin Dabigatran Apixaban |
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Give 2 examples of antiplatelet drugs |
Aspirin Clopidogrel |
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what is the mechanism of actions of warfarin |
Warfarin is vitamin Kepoxide reductase antagonist, which then inhibit the synthesis of biologically functional factors of coagulation cascade; factors IX, X, VII and II in the liver This enzyme is essential for recycling vitamin K, and vitamin K is an essential co-factor. |
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Warfarin exists as racemic mixture. which enantiomer is more potent? |
S-warfarin is 4 times more potent than R-warfarin |
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What are the drugs that increase warfarin metabolism; reduce anticoagulant effect? |
carbamazepine, primidone, phenytoin, rifamycin |
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What are the drugs that reduce warfarin metabolism? |
cimetridine, amiodarone |
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what is the formulation of warfarin? how long does it take to work? |
it is only works in vivo orally active takes several days to achieve anticoagulant effects |
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what are the major concerns of warfarin? |
- risk of bleeding - teratogenic (not for pregnant ) - possible drug and diet interactions - INR monitoring required |
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what is INR? |
International normalisation ratio; measures how long it takes your blood to clot High INR, higher risk of bleeding |
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what is the mechanism of action of heparin? |
Heparin typically lines the walls of the vascular endothelium and its function isto inhibit the coagulation of blood. It does this by potentiating the activity ofantithrombin III – which inhibits both thrombin and factor IIa (key componentsof the coagulation cascade).
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what are the concerns of heparin? |
- risk of bleeding - can cause serious hypersensitivity reactions - physical incompatibility with many drugs |
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what are the types of heparin available? |
- High molecular weight heparin - low molecular weight heparin - synthetic pentasaccharides |
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explain what is high molecule weight heparin. drug source bioavailability formulation |
- isolated from bovine lung or porcine intestine mucosa - IV administered only as salt form - because HMWH is a mixture of different polysaccharides with different affinities, the dosing cannot be calculated based on mg of drug - But because of the high density of negative charge and high molecularweight heparins bind non-specifically to proteins, cells, platelets,macrophages....low bioavailability |
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what does 1 unit of heparin mean in HMWH? |
1 unit of heparin = the amount of heparin required to prevent 1 mLof sheep blood from clotting for 1 hr
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explain low molecular weight heparin |
smaller polysaccharides (4-6 kDa), morehomogeneous
• Less non-specific binding to proteins, cells etc.... • 90% is absorbed after subcutaneous injection - more bioavailable than highmolecular weight heparin • Still contains the same pentasaccharide motif but - more selective forfactor Xa than thrombin |
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explain Synthetic pentasaccharides |
Chemically synthesised - heterogeneityproblem is eliminated.• Improved bioavailability, more selective than heparin and less variability
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what are dabigatran etexilate |
direct thrombin (IIa) inhibitor
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what are apixaban and rivaroxaban |
direct Xa inhibitors
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which enantiomer of clopidogrel pharmacologically active? |
It isadministered as a single enantiomer - the S enantiomer. The corresponding Renantiomer is devoid of antithrombotic activity.
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Clopidogrel has a mechanism of action as bioactivation. what is bioactivation? |
Clopidogrel is rapidly metabolised in the liver – and it is one of the resultingmetabolites which reacts with PY12 and prevents clotting.
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