Thrombolytic Drugs Flashcards
What classes of drugs are antiplatelet?
Aspirin, ADP receptor antagonists, GpIIb-GpIIIa receptor inhibitors
How does Aspirin (acetylsalicylic acid) work?
irreversible COX-I inhibitor
What is the general mechanism for ADP receptor antagonists?
irreversibly bind ADP receptor and prevent activation of platelets
What drugs are ADP receptor antagonists?
Ticlopidine, Clopidogrel, Prasugrel
-used in stents for ppl that don’t tolerate aspirin
What is the mechanism of Dipyridamole?
increases cAMP by blocking phosphodiesterase 3 –> inhibits platelet activation
- little benefit on own
- use with warfarin/aspirin
What drugs are GpIIb-GpIIIa receptor inhibitors?
Abiciximab, Eptifibatide, Tirofiban
What is the MOA for GpIIb-GpIIIa?
prevent binding of adhesive glycoproteins (fibrinogen/vWF) to activated platelets –> inhibits common pathway
What is specific about GpIIb-GpIIIa use?
IV admin.
used during angioplasty with heparin and aspirin
What drugs are the anti-coagulants?
Heparin (and derivatives), Dabigatran etexylate, Fondaparinux
-inhibit thrombin
What is the action of heparin?
binds to thrombin and DIRECTLY inhibits the enzyme from converting fibrinogen –> fibrin
What drugs are heparin derivatives?
lepirudin, bivalirudin, argatroban
also dabigatran etexylate (oral)
What is unique about admin. heparin and its derivatives?
must be admin. via IV
-Dabigatran etexylate is oral
What are the indirect inhibitors of thrombin (indirect anti-coags)?
unfractionated heparin (HMW), LMWH, Fondaparinux
What is the action of indirect anti-coag drugs?
enhance action of Antithrombin III to inhibit Factor Xa (results in no thrombin)
What is unique about Unfractionated Heparin and LMWH?
can bind antithrombin and thrombin to cause thrombin inhibition
-Fondaparinux cannot bind thrombin
What test is used to monitor heparin dosing?
partial thromboplastin time (PTT)
-LMWH doesn’t need to be monitored
What is the action of protamine?
heparin antidote
What is the mechanism of protamine?
basic, + charged molecule binds - charged heparin to form stable complex that isn’t active
What is the action of Warfarin?
inhibits conversion of oxidized Vitamin K epoxide to reduced Vitamin K hydroquinone
What is Vitamin K needed for in coagulation?
needed for gamma carboxylation of factors II, VII, IX, X, and Protein C and S
Why is a patient on Warfarin initially hypercoagulable?
warfarin inhibits Protein C and S first that inhibit clotting; takes a few days before all of reduced Vit. K can be used up
-must admin another drug to bridge patient
How is warfarin monitored?
INR (PT) - looks at Factor VII, which is the first to be affected
What causes people to require different doses of Warfarin?
polymorphisms in VKOR1 gene
What is the major issue with Warfarin?
low Tx index and tons of drug interactions
