Pharm - Coagulation Disorders Flashcards
COX inhibitors (antiplatelet drugs)
Aspirin (Ibuprofen)
ADP P2Y12 inhibitors (Antiplatelet drugs)
Clopidogrel, Ticlopidine, (Prasugrel)
Phosphodiesterase Inhibitors (Antiplatelet drugs)
Dipyridamole (Boner Pills)
GpIIb/IIIa inhibitors (antiplatelet drugs)
Abciximab, Eptifibatide (Tirofiban)
PAR-1 inhibitors (Antiplatelet drugs)
Vorapaxar
Aspirin MOA
irreversible COX-1 inhibitor, reduces TxA2 production, reduces platelet aggregation
P2Y12 receptor antagonists MOA
Clopidogrel, Ticlopidine, Prasugrel –> block effect of ADP at receptor, inhibit platelet function/activation/aggregation
GpIIb/IIIa antagonists MOA
Abciximab, Eptifibatide, Tirofiban –> block binding of fibrinogen to activated platelet receptor
PDE inhibitor MOA
Dipyridamole –> inhibits the catalysis of cAMP and cGMP –> elevated cAMP levels inhibit platelet function
PAR-1 antagonist MOA
Vorapaxar –> block thrombin-induced platelet aggregation
Major adv effects of platelet inhibitors
bleeding
Contraindications to use of platelet inhibitors
pts w/ conditions pre-disposing them to bleeding –> PMH of active pathological bleeding, trauma, surgery,
Aspirin and Ibuprofen - both act on COX - which one is irreversible? (and other one is reversible)
Aspirin = irreversible (ibuprofen = reversible)
What effect does aspirin have on the PT or PTT?
none
Why does aspirin have specificity for the platelet? (B/c endothelial cells have COX also)
platelets are anucleat –> have no ability to recover from COX inhibition, b/c cannot synthesize more. Endothelial cells can regenerate COX
What do endothelial cells COX produce, why is it impt?
PGI2, it inhibits platelet action
What does the dose/response profile for aspirin look like compared to the dose/risk profile? (Idk how to ask this question)
there is no additional clinical effect w/ increased dose, only increase risk
Adverse effects of aspirin
GI related, they are dose dependent –> severely toxic in high doses (suicide), hepatic and renal toxicity
contraindications for aspirin use
previous hx of aspirin-induced bronchospasm
what happens when ADP binds the P2Y12 receptor on platelet surface
inhibition of adenylyl cyclase –> lower levels of cAMP, platelets have less inhibition
P2Y12 inhibitors - reversible or irreversible
Clopidogrel, Ticlopidine, Prasugrel –> irreversible
–> persistence of effect ~10 days
black box warning for Clopidogrel
poor Cyp2C9 metabolizers –> at risk for reduced response, genetic tests available
black box warning for Ticlopidine
second line tx due to life threatening hematologic toxicities –> agranulocytosis, neutropenia, thrombocytopenia, TTP, anemia
route of excretion for the P2Y12 inhibitors
Clopidogrel, Ticlopidine, Prasugrel –> hepatic/renal elimination
PDE inhibitor MOA
Dipyridamole –> induce elevations in cAMP –> block release of AA from membrane phospholipids, reduce TxA2 –> less inhibition of platelets
also, stimulates release PGI2 (prostacyclin) which induces adenylate cyclase, thus raising cAMP levels , inhibit platelet aggregation even more
Sweatman quote about Dipyridamole
“It is uninteresting w/ regards to adverse effects”
GpIIb/IIIa inhibitors route of admin
Abciximab, Eptifibatide, Tirofiban –> IV
Abciximab
Fab fragment of chimeric monoclonal Ab –> NONCOMPETITIVE (causes steric hindrance, conformational change) of GpIIb/IIIa site
Abciximab reversible or irreversible
irreversible - protracted duration up to 2 weeks
Reactions seen to these GpIIb/IIIa antagonists
Abciximab, Eptifibatide, Tirofiban –> anaphylactic reactions
adv effect seen with Abciximab
thrombocytopenia –> numan anti-chimeric Ab formation to abciximab
PAR-1 antagonist route of admin
Vorapaxar –> oral
Vorapaxar half life / reversibility
technically reversible –> but t1/2 = 8 days –> effectively irreversible
Vorapaxar persistence
up to 4 weeks –> Holding a dose will do NOTHING to correct bleeding or reduce risk
PAR-1 antagonist metabolism/elimination
Vorapaxar –> hepatic metabolism (3A4) - fecal elimination
Herbal Product Interactions w/ antiplatelet drugs
Ginkgo Biloba - antiplatelet properties
garlic - antiplatelet properties
ginger - inhibits TxA synthetase, a platelet aggregation inducer
indirect thrombin inhibitors (anticoagulant drugs)
Heparin
Heparin antidote
protamine sulfate
direct thrombin inhibitors (anticoagulant drugs)
Dabigatran (Bivalirudin, Lepirudin)
Factor Xa inhibitors (anticoagulant drugs)
Enoxaparin, Apixaban, Rivaroxaban (Fondaparinux)
inhibitor of clotting factor synthesis (anticoagulant drug)
Warfarin
Warfarin antidotes
prothrombin complex, Phytonadione vit K1
Heparin route of admin
IV