Anti-Platelets Flashcards
What do the GPIa/IIa and GPIb bind to in order to start the clotting cascade?
GPIa/IIa -> binds vWF
GPIb -> binds collagen
These bind to damaged endothelium inducing fibrinogen binding and making TXA2
What do PAR1/PAR4 receptors interact with?
PAR1/PAR4 bind to Thrombin (IIa) to become activated.
What do P2Y1/P2Y12 respond to become activated?
ADP
What is produced by endothelial cells to inhibit platelet aggregation?
PGI2, produced by COX in the endothelium
What is an irreversible inhibitor of COX?
Aspirin. Prevents TXA2 production in platelets for 7-10 days, but preserves endothelium production of PGI2.
Why is Aspirin used?
Mild prevention of thrombus for MI, CVA, and helps with angina. Can cause GI irritation, dose dependant.
How does Dipyridamole work?
PDE3 Inhibitor, causes blocking of adenosine uptake, and increase cAMP - prevent platelet aggregation.
What is Dipyridamole primarily used for?
Used to prevent thrombi with prostetic heart valve, used with Warfarin. Can cause GI irritation and Headache.
What drug is the only reversible antagonist of P2Y12?
Ticagrelor, advantageous in patient about to undergo surgery to prevent thrombi afterwards.
Which ADP prodrug (P2Y1/P2Y12) Receptor blocker has the fastest onset time?
Prasugrel, due to efficient generation of metabolites by multiple methods.
What prodrugs are activated by CYP2C19?
Clopidogrel and Ticlopidine
How is the activity of Prasugrel different from Clopidogrel?
Prasugrel is more potent and has a more consistent level of inhibition with faster onset.
What can cause changes in activity of patient’s taking Clopidogrel and Ticlopidine?
Very common polymorphisms of CYP2C19, especially in asain decent, which cause poor metabolizers, thus less activity from the drug and clot prevention. Additionally, taking proton pump inhibitors can cause decreased activity of Clopidogrel as well.
When is Clopidogrel indicated for use?
Unstable Angina or NSTEMI (with ASA)
Recent MI or Stroke.
Peripheral vascular disease
When is Prasugrel used?
To reduce the risk of thrombi when undergoing cardiovascular intervention.
When is Ticagrelor used?
Irreversible inhibitor of ADP receptor. Used with ASA to prevent thrombi with NSTEMI/STEMI patients that were managed medically or if they had a CABG
What antiplatelet drug can cause neutrapenia?
Ticlopidine, less commonly used and has been replaced by others.
Which antiplatelet can cause dyspnea?
Ticagrelor
What is the antibody that binds to the GbIIb/IIIa receptor?
Abciximab. Binds to the receptor and prevents fibrinogen from binding noncompetitively.
What does the GbIIb/IIIa receptor bind and do?
Binds fibrinogen and caused platelet aggregation
What drug is used with Alteplase and Heparin for thrombolysis?
Abciximab. Can also be used after undergoing stenting to prevent restenosis. IV only, 7 days lasting.
How does Eptifibatide work to prevent aggregation?
Eptifibatide is a cyclic heptapeptide that binds in the GbIIb/IIIa receptor competitively preventing fibrinogen from binding. Fast onset with short half life.
When is Eptifibatide used and what are adverse side effects?
Used with unstable angina, NSTEMI, STEMI with LMWH. Also patient undergoing intervention to prevent clotting.
Can cause bleeding, thrombocytopenia, hypotension, and bradycardia.
