Bleeding Disorders and Assessment part 2 Flashcards
clopidogrel (Plavix)
oral prodrug metabolized by liver
what percent of clopidogrel (Plavix) absorbed becomes the active form?
15%
what is the half life of clopidogrel (Plavix)?
8 hours
how long does the effect of clopidogrel (Plavix) last for?
platelet’s lifetime
what does clopidogrel (Plavix) bind irreversibly to?
P2Y12 ADP receptor on platelet surface
clopidogrel (Plavix) can be used as a secondary prophylaxis in patients with what?
- myocardial infarction
- stroke
- peripheral arterial disease
combo of clopidogrel (Plavix) and aspirin was shown to be superior over aspirin alone after what?
- acute coronary event
- percutaneous coronary interventions (PCI)
- coronary stent placement
T/F: clopidogrel (Plavix) is more expensive than aspirin
true
cons of using clopidogrel (Plavix)
results in more clinical bruising/bleeding than aspirin
T/F: like aspirin, clopidogrel (Plavix) is generally safe to continue through most oral surgery
true
other P2Y12 blockers
- ticlopidine (Ticlid)
- Prasugrel (Efient)
- direct acting, reversible inhibitors
T/F: ticlopidine (Ticlid) has at least 5 metabolic pathways and less variable clinical response
true
ticlopidine (Ticlid) has a more rapid onset than what?
clopidogrel
dipyramidole has antiplatelet effect by inhibition of what?
phosphodiesterase
what happens when dipyramidole inhibits phosphodiesterase?
results in intracellular accumulation of cyclic AMP
dipyramidole is a potent inhibitor of what?
platelet aggregation in vitro
what are the most potent inhibitors of platelet aggregation?
glycoprotein receptors IIb/IIIa inhibitors
glycoprotein receptors IIb/IIIa inhibitors are competitive inhibitors for what?
fibrinogen binding to platelet IIb/IIIa receptor
coumadin
oral vitamin K antagonist
what does coumadin block?
essential vitamin K-dependent carboxylation of coagulation factors II, VII, IX and X
what happens when coumadin blocks coagulation factors II, VII, IX, and X?
- results in formation of biologically inactive proteins
2. decreases the coagulant activity of these factors in plasma
effect of coumadin is a fxn of what and not the drug itself?
fxn of the decay in the concentration of the coagulation factors
half life of vitamin K-dependent coagulation factors
ranges from 6 to 60 hours
the full effect of coumadin is delayed for how long?
2-3 days
full restoration of normal coagulation after termination of coumadin therapy requires how long?
at least 3-5 days
dose-effect relationship of coumadin varies considerably due to what?
- binding to palsma albumin
- variable vitamin K intake
- variable clearance by the liver
what is used to monitor effect of coumadin?
PT/INR
what is the most important side effect of coumadin treatment?
bleeding
rare coumadin-induced skin necrosis may occur and is usually associated with what?
protein C deficiency
Pradaxa (dabigatran)
direct thrombin inhibitor
factor Xa inhibitors
- Xarelto (rivaroxaban)
- Eliquis (apixaban)
- Savaysa (edoxaban)
why do the new oral anticoagulants (i.e. direct thrombin inhibitor and factor Xa inhibitors) not require regular lab monitoring unlike coumadin?
not affected by diet, liver fxn, etc
onset time of new oral anticoagulants (i.e. direct thrombin inhibitor and factor Xa inhibitors)
rapid onset of 2-3 hours