Pharm - Anticoag Basics Flashcards
Warfarin’s MOA is what?
Inhibits the formation of multiple clotting factors by de-activating Vitamin K.
What are the enzymes used to metabolize Warfarin?
3A4 and 2C9
Why does it matter that Warfarin is highly protein bound?
Other highly protein-bound meds (Digoxin) can push Warfarin off proteins and increase blood levels.
Is Warfarin fast-acting or slow-acting?
Slow: can take 5-10 days because of it’s MOA.
When would you want to avoid Warfarin?
Pregnancy.
Any bleeding risks (including fall risks)
After CNS/ocular surgery (brain bleed risk)
Spinal catheters/aneurysms (spinal hematoma risk)
Anyone who can’t adhere to it.
Anyone with hepatic disease or alcoholism.
What’s the INR goal for Warfarin?
2-3 in most cases.
2.5-3.5 for mitral valve replacements.
INR: which way is thinner?
Higher number is thinner - less coagulability.
What sorts of things will increase the INR (make blood thinner?)
Anything that inhibits CYP3A4 or 2C9. Lots of alcohol. Decreasing Vitamin K. Acute infection or diarrhea. CHF or CKD. Liver disease.
What sorts of things will decrease the INR (make blood more likely to clot)?
Anything that induces 2C9 or 3A4. Poor intestinal absorption. Increased Vitamin K ingestion. Smoking Hypothyroidism. Chronic alcohol ingestion. Missing a dose.
What are the AEs with Warfarin?
Bleeding risk (esp GI, intracranial)
Necrosis of skin/adipose tissue
Purple toe syndrome
What do you need to educate pt about with Warfarin when they start taking it?
Dosing/Adherence: monitoring, taking daily, what to do if you miss a dose.
Diet/drug interactions: Keep Vit K steady, limit alcohol, tell all providers.
Signs of bleeding or clotting: stroke. Internal. Calling 911.
Routine pt education with warfarin includes
INR
Specific Bleeding and thromboembolism s/s
Changes in meds, diet, alcohol consumption, smoking, diseases.
Missed doses.
Duration of therapy
Dabigatran: what is it?
A DOAC (direct-acting oral anticoagulant).
What to know about DOACs, generally
Kidney function must be good. Can’t use with liver disease. Can’t use with strong 3A4 inhibitors or inducers. Can’t use with cancer. Can’t use if body weight is extreme. They’re expensive. They’re hard/expensive to reverse.
What to know about dabigatran, specifically?
80% renal metabolism (can’t use in kidney disease).
Works on Factor II (thrombin).
NOT a CYP substrate (exception).
Take it twice a day.
What is apixaban?
A DOAC (direct-acting oral anticoagulant).
What to know about apixaban, specifically?
CYP 3A4.
Works on Factor 10a. Have to take it twice a day.
Do DOACs have food monitoring?
No. Only warfarin.
Do DOACs have INR monitoring?
Nope.
MOA of DOACs?
Direct inhibition of 2a or 10a.
UFH: Unfractionated Heparin, SubQ administration tips.
2in away from belly button
1/2in-5/8in needle, 25/26g.
Don’t ever administer IM.
With heparin, why do you monitor platelets and H&H?
For safety reasons. Don’t want bleeding and don’t want HIT. Monitored daily.
For heparin, why do you want to measure aPTT?
To make sure it’s at therapeutic levels.
How long does HIT take to develop? What is the effect?
5-14 days after heparin exposure.
Thrombosis, thrombocytopenia.
What medication do you use to reverse heparin or LMWH od?
Protamine Sulfate, IV over 10m.
Be aware of fish allergy
What should we know about low molecular weight heparin?
Less HIT risk.
Longer half-life.
Eliminated really.
No aPTT monitoring.
What is Fondaparinux?
Synthetic Unfractionated heparin. NO HIT reaction. No macrophage/plasma protein binding. No monitoring. SubQ.
What is Bivalrudin?
Inhibitor of thrombin.
IV admin.
Renal elimination.
Good in pts with HIT hx or high bleeding risk.
What are SEs of Bivalirudin?
Headache, Hypotension, Pain (back, abdominal, pelvic).
Serious bleeding if combined with other bleeding drugs.
What is Argatroban?
Direct thrombin inhibitor. IV admin Hepatic elimination. Useful in pts with hx of HIT with an active thrombosis. Common to have allergic reactions.
