Antithrombotics

Question 1

Arachidonic Acid (AA) vs. Eicosapentaenoic Acid (EPA)

Answer 1

Higher AA in diet: makes PGH2 to TxA2 = platelet aggregation and ADP release

Higher EPA in diet: makes PGH3 to TxA3 = no platelet aggregation and ADP release

Question 2

Platelet Hyperactivity

Answer 2

HTN, increased cholesterol, diabetic, and obese patients

Higher risk for thrombo-embolic events

Question 3

ADP and Thrombosis

Answer 3

vWF, collagen, TxA2, and thrombin = dense granule release of ADP causing stimulation of P2Y12, which allows for:
Increased granule release
Recruitment of Platelets
More coagulation and aggregation

Overall, maintains thrombus growth and stability

Question 4

Aspirin

Answer 4

Antiplatelet agent - inhibits COX -1 and COX -2

Question 5

ADP Receptor Antagonists

Answer 5

Antiplatelet agents- irreversible via binding P2Y12

Ticlopidine
Clopidogrel
Prasugrel

Question 6

Inhibitors of Platelet Receptors (GPIIb-IIIa)

Answer 6

Antiplatelet agents - inhibit binding of fibrinogen to GPIIb-IIIa

Abciximab
Eptifibatide
Tirofiban

Question 7

PDE Inhibitors

Answer 7

Antiplatelet agents - inhibits platelet aggregation

Dipyridamole

Question 8

Uses for Antiplatelet Agents

Answer 8

Patients with MI/past MI
Symptoms from atherosclerosis including angina, TIAs, or intermittent claudication
Following coronary artery bypass grafting (CABG), coronary artery angioplasty/stent, acute thrombotic stroke, A-fib if contraindication to oral anticoagulants

Question 9

MI Pathway

Answer 9

If ASA intolerant or had an MI while on ASAs, then replace with Clopidogrel

If 10 year risk is:
greater than 1.5%/year = ASA

Question 10

Therapeutic Window

Answer 10

Need to give dose within therapeutic window
If less: increase risk of bleeding
If more: increase risk of ischemia

Question 11

Fibrinolytic Drugs

Answer 11

Cause fibrinolysis - use for acute MI (within 12 hrs onset), thrombotic stroke (3 hrs onset), DVT, PE, clearing shunts, and actue arterial thromboembolism

Strepokinase
Urokinase
t-PA
Reteplase
Tenecteplase

Question 12

Natural Inhibitors of Fibrinolysis

Answer 12

PAI- 1: inhibits plasminogen to plasmin

alpha-antiplasmin: inhibits plasmin from activating fibrinogen to fibrin degradation

Question 13

Aminocaproic Acid

Answer 13

Inhibitor of Fibrinolysis
Similar to Lys
Synthetic
Competitively inhibits plasminogen activation
Taken orally and eliminated via kidney
Used for bleeding due to fibrinolysis and hemophilia tx

*make sure kidney function is normal

Question 14

Tranexamic Acid

Answer 14

Inhibitor of Fibrinolysis
Analog of aminocaproic acid
Inhibits plasminogen activation 
More potent than aminocaproic acid
Lower dose = less side effects