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What part of the clotting cascade that includes the contact activation system? Or in other words, the part of the pathway that occurs entirely within the vasculature?
When do the intrinsic and extrinsic pathways come together to make the final common pathway??
upon the activation of Factor X.
Review: Platelets act first to tissue injury (when you're bleeding) to form a platelet plug. This then activites the clotting factors. Factor X converts factor II (prothrombin) to IIa (thrombin) and IIa converts fibrinogen to fibrin clot (thrombus). Ischemia and necrosis occur distal to the clot and that is when you get MI, stroke, PE and VTE.
What is the goal of therapy when prescribing anticoagulants?
promote anticoagulation while minimizing hemorrhagic complications thru careful monitoring
Heparin is normally monitored with ___ levels. What drugs can not be monitored with this lab?
LMWH (Lovenox) -- less risk of bleeding with LMWH compared to Heparin.
It is important to remember that Heparin has no effect on _____.
Existing clots... it only prevents the clot from getting larger or new clots from forming.
What is the MOA of Heparin?
Binds with antithrombin III at 2 sites. First site has an effect on factor X. Second site is at the conversion of prothrombin to thrombin.
What is the MOA of Warfarin?
Inhibits clotting factors that depend on Vit K for synthesis; II,VII, IX, X and coagulation inhibitor proteins C&S.
*remember, these drugs will not break existing clots. They only prevent clots of forming. They only work on new clotting factors as well. They will not work on existing clotting factors.
What is the GOLD STANDARD for monitoring Warfarin?
How many times a day is Warfarin typically dosed?? Why is this?
once a day, long half life
*also has a very narrow therapeutic window so monitoring this drug is crucial!
For prevention of DVT... the INR should be?
For prevention of recurrent thrombosis, the INR should be?
For a tissue cardiac valve replacement, the INR should be?
For a MECHANICAL cardiac valve replacement, the INR should be?
2.5 - 3.5
For a recurrent systemic embolism, the INR should be?
What is the MOA of aspirin?
prevents platelet aggregation by inhibiting cyclooxygenase in platelets and endothelial cells, preventing synthesis of thromboxane A2 and prostacyclin (both are potent platelet aggregators and vasoconstrictors)
What is the MOA for Plavix?
inhibits the binding of ADP to its platelet receptor and the subsequent ADP-mediated activation of the GPIIB/IIIa complex.
-this process is irreversible.. once platelets are affected, it affects them for their lifespan (10 days?? --- previously in notes it says 3-5days?)
If you are treating a patient short term for a DVT with LMWH and warfarin, when should you stop the LMWH?
- D/c when INR is >2
- Should give LMWH for a min of 5 days.
- *if this the first time a patient has had a DVT... treat them for 6 months.
- *If the reason for the DVT is unknown, treat the patient for 6-12 months and keep the INR 2-3.
What drugs should be prescribed in the treatment of ischemic heart disease?
- ASA and oral anticoags.
- antiplatelets are beneficial as well
What is the treatment of choice for a massive or life threatening PE?
What is the preferred treatment over ASA for patients with recent TIA or minor stroke?
(this will help reduce the chance of another stroke)
Is it okay to change patients from Coumadin to Warfarin during dose adjustments??
- different bioavailabilities
- steady state will not be maintained when altering drug dosages based on INR
It is suggested to hold Warfarin if INR is >____.
What is the DOC for prevention of thromboembolic events in patients with atherosclerosis?
- ASA works better on arteries
- Heparin and Warfarin work better on veins
PTT reflects the ___ pathway and is typically used to monitor ___ therapy.
PT and INR results are used to monitor what drug?
PT measures which pathway?
How many dosages of Warfarin are required with subsequent INR monitoring before dosages should be adjusted?
How should an INR be monitored with initial treatment??
- Every 2 to 3 days until your goal is met
- Then every week--- if still at goal
- Then every 2 weeks
- And finally monthly
- When stable dose and INR are demonstrated.
Is it necessary to monitor for coagulation parameters with hemorheolgic agents (Pletal)?
Monitor CBC, platelets, UA, stool and hemoccult periodically based on existing medical conditions.
What preggo category is Warfarin?
Besides bleeding, what is the biggest side effect of platelet inhibitors?
(take with meals to prevent upset)
Patients should avoid ___ when taking aspirin.
NSAIDS... increased risk for bleeding.
What strength tablets is Warfarin available in?
1, 2, 2.5, 3, 4, 5, 6, 7.5, and 10 mg tabs
What is the recommended starting dose for Warfarin?
What about in the elderly?
- 5mg daily for 5-7 days --- monitor INR
- 2.5 for elderly (must monitor them more closely.. risk for bleeding and injury increased).
In regards to diet, it is important for patients to remember to avoid what 2 things with Warfarin treatment?
High Vit K in diet and rapid weight loss.. these will alter the effectiveness of Warfarin
*high vit k foods --- broccoli, cucumber, spinach, green tea, brussel sprouts (Green foods typically)