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48 Cards in this Set

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Indication for anti-platelet agents?
arterial thrombosis
Approaches to anti-platelet therapy? (4)
1. inhib platelet adhesion
2. inhib platelet activation/secretion
3. inhib platelet aggregation
4. inhib procoagulant activity
Ligand/receptor for platelet adhesion?
vW factor/ glycoprotein Ib/IX
Ligand/receptor for platelet aggregation?
Fibrinogen/ GPIIb/IIIa
Platelet activating substances? (4)
1. Thromboxane
2.PAF
Indication for anti-platelet agents?
arterial thrombosis
Approaches to anti-platelet therapy? (4)
1. inhib platelet adhesion
2. inhib platelet activation/secretion
3. inhib platelet aggregation
4. inhib procoagulant activity
Ligand/receptor for platelet adhesion?
vW factor/ glycoprotein Ib/IX
Ligand/receptor for platelet aggregation?
Fibrinogen/ GPIIb/IIIa
Platelet activating substances? (4)
1. Thromboxane
2.PAF
3. ADP
4. Collagen
What does prostacyclin (PGI2) do for cAMP and aggregation?
increase cAMP, decrease aggregation
What does Thromboxane (TXA2) do for cAMP and aggregation?
decrease cAMP, increase aggregation
Platelet phospholipid surface crucial for?
coagulation cascade
Name the two ADP receptor inhibitors
Ticlopidine
Clopidigrel
What do ADP -receptor blockers do?
inhibit ADP-induced platelet aggregation
What is ticlopidine a derivative of?
Thienopyridine (prodrug)
What does ticlopidine do?
blocks ADP receptor, inhibiting platelet aggregation and degranulation
When is ticlopidine used?
unstable angina, TIAs, stroke, peripheral vascular disease. After placement of intracoronary stents
What are ticlopidines side effects? how bad are they?
nausea, diarrhea, hemmorhage, neutropenia - BAD
What is clopidogrel a derivative of?
Thienopyridine
What does clopidogrel do?
irreversibly blocks ADP receptors
How long does it take for clopidogrel to take effect?
4 -7 days (lasts 7-10)
When is clopidogrel used?
acute coronary syndrome; risk reduction in pts with recent CVA, MI or PAD
What did the CAPRIE trial show?
clopidogrel slightly better than aspirin in preventing MIs and strokes
What did the CURE study show?
aspirin + clopidogrel better than aspirin alone in preventing MI/stroke/CV death (20% risk reduction)
What is a dangerous condition associated with both clopidogrel and ticlopidine?
TTP - meds block ADAMTS13
With patient on ticlopidine or clopidogrel, how do you check for TTP?
check platelets weekly (1st month of treatment), educate on warning signs of TTP
What would thrombin receptor inhibitors do?
Block platelet activation and aggregation, some under development, none on market
What does aspirin do? (4 steps)
Irreversibly inhibits COX-1 which inhibits arachadonic acid generation which inhibits TXA2 secretion which inhibits platelet activation
How long until aspirin takes effect? How long does it last?
15-20 min, 7 days
What is the long-term use dose of aspirin?
81 mg
Why use a low dose of aspirin?
fewer GI side effects, less risk of bleeding, similar antiplatelet effects
Who is on lifelong aspirin?
Pts with ACS, CVA, or PCI
What is the anti-platelet mechanism of PDE inhibitors?
less PDE means less breakdown of cAMP which means less platelet function
What are the PDE inhibitors? (3)
Dipyridamole, Cilostazol, Aggrenox (aspirin + dipyridamole)
How do GPIIb/IIIa inhibitors work?
bind to activated receptor and directly block platelet aggregation, "final common pathway"
What are the three GPIIb/IIIa inhibitors?
1. Abciximab
2. Eptifibatide
3. Tirofiban
What is abciximab?
a chimeric antibody to the GPIIb/IIIa receptor
How is abciximab given?
IV and short term
At what occupancy does abciximab completely inhibit ADP-induced platelet aggregation?
80%
What is eptifibatide?
A cyclic heptapeptide from snake venom that selectively blocks GPIIb/IIIa receptors and prevents platelet aggregation
When is eptifibatide used?
prevention of thrombosis in PCTA (percutaneous angioplasty), MI, angina
What is the t1/2 of eptifibatide and where is is cleared?
2.5 h, the kidney
What is tirofiban?
snake venom GP IIb/IIIa receptor inhibitor.
When is tirofiban used?
PCTA, MI, unstable angina
What did the PRISM-PLUS study find (wrt tirofiban)?
adding tirofiban to heparin decrease risk of repeat MI/death by 35% in 7 days post MI
How often does thrombocytopenia occur with GPIIb/IIIa inhibitors?
0.5% of exposures, more with abciximab, more with repeat exposures
How is the thrombocytopenia following GPIIb/IIIa inhibitors mediated?
Through naturally occuring abs that don't require prior exposure (=weird)