session 11 Flashcards
What is the most common oral anticoagulant?
Warfarin (Coumadin)
Newer agents are gaining popularity.
What is the mechanism of action of Warfarin?
Inactivates vitamin K in the liver and interferes with the formation of vitamin K-dependent clotting factors (prothrombin, factors VII, IX, X)
Delayed onset (2-7 days) due to the long half-life of prothrombin.
What are the primary adverse effects of Warfarin?
Primarily bleeding.
What is the reversal agent for Warfarin?
Vitamin K.
List the indications for Warfarin.
- Post-acute MI with LV thrombus
- Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT)
- Atrial fibrillation and prosthetic heart valves
- Recurrent ischemic strokes and TIAs (transient ischemic attacks)
What is the initial dosing for Warfarin?
5mg/day.
What does INR stand for and what is its goal for most indications?
International Normalized Ratio; goal 2-3.
What should be monitored when a patient is on Warfarin?
PT (Prothrombin Time) and INR.
What enhances the response to Warfarin?
- Alcohol
- Aspirin
- Many others.
What decreases the response to Warfarin?
- Antacids
- Barbiturates
- Some others.
Why is consistent intake of vitamin K-rich foods important for patients on Warfarin?
To avoid altering INR.
What is the action of Heparin?
Enhances antithrombin-III action; prevents clot expansion.
What are the adverse effects of Heparin?
Bleeding and potential heparin-induced thrombocytopenia.
List the indications for Heparin.
- Acute MI
- Coronary syndromes
- Atrial fibrillation.
What does PTT stand for and what is its therapeutic range?
Partial Thromboplastin Time; therapeutic range 1.5-2x control.
What are the advantages of Low-Molecular-Weight Heparin (LMWH)?
Greater bioavailability, longer half-life.
What is the action of Low-Molecular-Weight Heparin (LMWH)?
Binds antithrombin-III and inhibits factor Xa.
What are common drugs classified as Low-Molecular-Weight Heparin?
- Enoxaparin (Lovenox)
- Daltaparin (Fragmin)
What is the action of Direct Thrombin Inhibitors?
Directly inhibit thrombin, reducing clot-bound thrombin activity effectively.
What is an advantage of Direct Thrombin Inhibitors?
Less bleeding risk with PCI.
What is the action of Fondaparinux?
Selectively inhibits factor Xa.
What are the advantages of Fondaparinux?
Once daily dosing, no platelet function inhibition.
What are the types of Novel Oral Anticoagulants (NOACs)?
- Direct thrombin inhibitors (e.g., Dabigatran)
- Factor Xa inhibitors (e.g., Rivaroxaban)
What is an advantage of NOACs compared to Warfarin?
Direct action, no need for routine bloodwork, fewer interactions.
