Antiplatelet and thrombolytic drugs Flashcards
Rx Tx of white clots
What’s the most effective therapy
Antiplatelet drugs
White clots are arterial and generally are more rich in platelets than red clots due to high shear in the injured vessel
Rx Tx of red clots
What’s the most effective therapy
Anticoagulation
Antiplatelet therapy is less effective
Venous thromboses are mostly fibrin and trapped RBCs
What enzyme synthesizes thromboxane A2?
Cyclooxygenase-1 and 2
Clopidogrel
MOA: irreversible blockade of ADP receptors (P2Y12) on platelets
Prodrug that requires CYP2C19
Can cause thrombotic thrombocytopenic purpura
What PPI Rx should be avoided with concurrent clopidogrel usage?
Omeprazole - inhibits CYP2C19 which activates clopidogrel
Use pantoprazole instead
What antiplatelet drugs are used in a Pt w/ high CV revent risk?
Ticagrelor and prasugrel
Alteplase
Recombinant tissue plasminogen activator (t-PA)
When should you avoid using tranexamic acid?
Contraindications:
Active intravascular clotting and subarachnoid hemorrhage
Cautions:
Renal impairment and thromboemoblic Hx
PGI2
Prostacyclin - prevents clotting
Which is a more potent platelet activator, TXA2 or ADP?
ADP
What activates platelets and causes expression of GIIb/IIIa
Thrombin
Collagen
ADP
TXA2
GIIb/IIIa is an integrin that binds fibrinogen and vWF
Antiplatelet Rx’s that block GP IIb/IIIa
-Abciximab
-Eptifibatide
-Tirofiban
What enzyme degrades fibrinogen?
Plasmin
What ADP receptor antagonist has increased risk for bleeding when used simultaneously with SSRI’s?
Prasugrel
What irreversible ADP antagonist is preffered for Tx of ACS?
Prasugrel
What reversal agent is used for an OD of Ticagrelor?
Bentracimab
What dose of aspirin should not be exceeded with simultaneous Ticagrelor Tx?
100 mg of aspirin is the daily limit when on ticagrelor
What antifibrinolytic can cause seizures at high doses?
Tranexamic acid
Rx used in hereditary angioedema
Tranexamic acid
Also used for epistaxis and after excessive thromblytic dosage
Desmopressin
Briefly increases factor VIII coagulant activity and increases plasma concentrations of vWF - accelerating and enhancing platelet adhesion respectively
Causes less smooth muscle contraction than vasopressin
Used for hemostasis in Pt’s w/ mild hemophilia A or vWF disease
A 55-year-old female with a history of myocardial infarction is prescribed clopidogrel. She is also taking omeprazole for gastroesophageal reflux disease. What is the concern with this combination of medications?
Reduced efficacy of clopidogrel - omeprazole inhibits CYP2C19 which is required to activate clopidogrel
Which of the following drugs is a direct thrombin inhibitor and is contraindicated in patients with a history of stroke or transient ischemic attack?
a. Aletplase
b. Vorapaxar
c. Digoxin
d. Clopidogrel
e. Aspirin
b. Vorapaxar
Which of the following antiplatelet agents binds the PGy12 receptor reversibly?
a. Aspirin
b. Clopidogrel
c. Abciximab
d. Vorapaxar
e. Ticagrelor
e. Ticagrelor
Which of the following drugs inhibits the conversion of plasminogen to plasmin and is therefore useful in treating bleeding due to systemic hyperfibrinolysis?
a. Heparin
b. Protamine sulfate
c. Aletplase
d. Clopidrogel
e. Tranexamic acid
e. Tranexamic acid
You’re treating a patient post PCI and stent placement. Prior to discharge you place them on an agent to reduce the risk of symptoms. This agent likely has what mechanism of action?
ADP (PGY12) receptor antagonist
E. PCI or CABG
Answer C. Antiplatelet ADP receptor antagonist is also a viable choice
Which ADP antagonist increases risk of subarachnoid hemorrhage?
Prasugrel
C. Glycoprotein IIa/IIIb receptor antagonism
In what Pt population presenting with A-fib is warfarin used over DOACs?
Pt’s with moderate-severe mitral stenosis or mechanical valves
