Anticoagulants Junk Flashcards
(53 cards)
What clotting factors are found within the Extrinsic Pathway?
VII, TF, X
What clotting factors are found within the Intrinsic Pathway?
XI, IX, VIII, X
What clotting factors are found with in the Common Pathway?
V, X, Thrombin (II), Fibrin (I), XIII
What is the MOA for Warfarin?
To inhibit the Vitamin K Reductase
- Causing a DECREASE in clotting factors.
What is the CYP what activates Warfarin?
CYP2C9
How long does it take before you may start seeing the effects of Warfarin?
About 3-5 Days; because it takes time to deplete all of the clotting factors from Reduced Vit K
- II: 60-100 Hours; VII: 4-6 Hours; IX: 20-30 Hours; X: 24-40 Hours
What is the initial dose of Warfarin?
5mg once daily
- Should overlap with a UFH/LMWH/Xa for 5 day AND until INR is normal
How to reverse a Warfarin Overdose?
-Can give high amounts of Vit K, which will reverse the inhibition of Vit K Reductase. Allowing for the clotting factors to be made again
-PCC [contains II, VII, IX, X, Protein C & S]
How do the genetic difference affect CYP2C9?
- 1*: normal wild type
- 2*: decrease clearance by 40-70%
- 3*: decrease clearance by 90%
-1/2: 20% dose reduction
-2/3 & 1/3: 35% dose reduction
-3/3: 80% dose reduction
How do the genetic difference affect VKORC1?
- A: Lower Dose; Higher Sensitivity
- G: High Dose; Lower Sensitivity
What is the cause of Warfarin Necrosis?
The initial dose of Warfarin will cause Protein C & S to become lower than the rest of the clotting factors [II, VII, IX, X] and also leaving factors V & VIII active as well = hypercoagulable
- can take with heparin to help with this
What is INR?
INR: the total time it take for the blood to clot
What drugs can increase INR?
Metronidazole, Amirodene, Cipro, Fluoxitine, Bactrim
- Will make it to where the blood clots slower
What drugs can decrease INR?
Rifampin
- Will make it to where the blood clots higher
What are the contraindications for Warfarin?
- Pregnancy: has the ability to pass through the plaecenta.
- Liver Disease: a lot of the clotting factors are made within the liver so if the liver is not making any of the clotting factors and warfarin decreases them even more = Warfarin will cause an INCREASED bleeding.
What is the MOA for heparin [UFH]?
It is going to bind to Anti-Thrombin, causing it to accelerate the action of it. This will cause inhibition of BOTH Thrombin and Xa; a long chain with a pentasaccharide binds to AT and wraps around and inhibits Thrombin or Xa.
What is the aPTT?
A test that determines how fast it takes for the blood to clot without TF
What are the adverse affects with UFH?
Iatrogenic Hemorrhage: hemorrhage at any site of injection
- >50 years old, HTN, Ulcers, Antiplatelet Drugs
HIT
Osteoporosis
What is HIT?
HIT - Thormbocytopenia: A decrease in the number of platelets
What is the mechanism of HIT?
Heparin will bind to the PF4 receptor on the platelet:
- Heparin + PF4 on the platelet will cause the antibody IgG to become activated. IgG will bind to Heparin + PF4 marking it for death. This is know as Type 2 [Immunogenic]; for first time users of Herparin, this may occur in 30 days while second time users may experience this within 1 day
-Heparin + PF4 on the platelet will cause the platelet to become activated, initiating the clotting cascade, causing an overall decrease in platelets
How to you reverse Heparin?
Protamine Sulfate: this will directly bind to the Heparin molecule causing inactivation.
- Doesn’t really affect the LMWH [Enoxiparin and Daltaparin]
- HAS NOT EFFECT AT ALL on fondaparinux
What is the MOA for Low Molecular Weight Heparins [LMWH]?
The MOA for the LMWH is pretty much the same as the MOA for UFH, but since this has a low molecular weight it the pentasaccharide chain is much shorter, ONLY inhibiting Xa.
What is the dosing for LMWH?
Enoxiparin:
-Prevention: 30mg BID (surgery) & 40mg daily (medical?)
-Treatment: 1mg SQ BID or 1.5mg SQ Daily
-Renal dysfunction: 30mg BID (prevent) & 1mg SQ Daily (medical)
Which ones work better within the Liver? UFH or LMWH?
UFH; LMWH do not!!
