Anticoagulants: vit K antagonists Flashcards
What is the first MOA of warfarin
Inhibits post-translational carboxylation of coag factors II (protrombin), VII, IX, and X
What is the 2nd MOA of warfarin
Inhibits 2 vit-k sensitive synthetic enzymes
How is warfarin reversed?
Pharmacological doses of Vit K
What is the Vit K agent used to reverse warfarin?
Phytonadione
What is the risk with IV phyotonadion?
Rare risk of anaphylaxis with rapid infusion
How do you start warfarin?
With heparin in cases of A-fib, DVT, PE
How long does it take warfarin to provide full anticoagulation?
5-7 days
How do you measure warfarin effects?
With prothrombin time (PT) and international normalized ration (INR)
What is the therapeutic INR range for AFib, DVT, PE?
2-3
What is the therapeutic INR range for mechanical heart valves?
- 5-3.5
* not porcine*
How long does it take a dose of warfarin to become effective?
48 hours
What is a complication of starting 10 mg of warfarin daily?
Warfarin induced skin necrosis
What drug interaction can cause increased risk of bleeding with warfarin and what do they do to the INR?
Drugs that inhibit CYP2C9
Increase INR
What drugs inhibit CYP2C9 and negatively interact with warfarin?
Bactrim
Flagyl
What drug interaction can cause increase risk of thrombosis with warfarin and what do they do to the INR?
Drugs that induce CYP2C9
Decrease the INR
What drugs induce CYP2C9 and negatively interact with warfarin?
Contraceptives
What are some sources of high dietary folate
Beef Pork liver Green teas Leafy green vegetables Spinach
Supratherapeutic INR treatments
See slide 47
What is an example of an anti-factor XA inhibitor and how does it come?
Fondaparinux
Pre-filled syringes
What is fondaparinux?
Synthetic pentasaccharide
How is fondaparinux eliminated?
Mainly renally
When is fondaparinux contraindicated?
CrCL<30
What is an unlabled use of fondaparinux?
DVT prophylaxis in pts w/ a h/o HIT
What is Rivaroxaban (Xarelto)?
An oral direct Xa inhibitor
