Pharm - Anticoag Basics

Question 1

Warfarin’s MOA is what?

Answer 1

Inhibits the formation of multiple clotting factors by de-activating Vitamin K.

Question 2

What are the enzymes used to metabolize Warfarin?

Answer 2

3A4 and 2C9

Question 3

Why does it matter that Warfarin is highly protein bound?

Answer 3

Other highly protein-bound meds (Digoxin) can push Warfarin off proteins and increase blood levels.

Question 4

Is Warfarin fast-acting or slow-acting?

Answer 4

Slow: can take 5-10 days because of it’s MOA.

Question 5

When would you want to avoid Warfarin?

Answer 5

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.

Question 6

What’s the INR goal for Warfarin?

Answer 6

2-3 in most cases.

2.5-3.5 for mitral valve replacements.

Question 7

INR: which way is thinner?

Answer 7

Higher number is thinner - less coagulability.

Question 8

What sorts of things will increase the INR (make blood thinner?)

Answer 8

Anything that inhibits CYP3A4 or 2C9. 
Lots of alcohol. 
Decreasing Vitamin K. 
Acute infection or diarrhea. 
CHF or CKD. 
Liver disease.

Question 9

What sorts of things will decrease the INR (make blood more likely to clot)?

Answer 9

Anything that induces 2C9 or 3A4. 
Poor intestinal absorption. 
Increased Vitamin K ingestion. 
Smoking
Hypothyroidism. 
Chronic alcohol ingestion. 
Missing a dose.

Question 10

What are the AEs with Warfarin?

Answer 10

Bleeding risk (esp GI, intracranial)
Necrosis of skin/adipose tissue
Purple toe syndrome

Question 11

What do you need to educate pt about with Warfarin when they start taking it?

Answer 11

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.

Question 12

Routine pt education with warfarin includes

Answer 12

INR
Specific Bleeding and thromboembolism s/s
Changes in meds, diet, alcohol consumption, smoking, diseases.
Missed doses.
Duration of therapy

Question 13

Dabigatran: what is it?

Answer 13

A DOAC (direct-acting oral anticoagulant).

Question 14

What to know about DOACs, generally

Answer 14

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.

Question 15

What to know about dabigatran, specifically?

Answer 15

80% renal metabolism (can’t use in kidney disease).
Works on Factor II (thrombin).
NOT a CYP substrate (exception).
Take it twice a day.

Question 16

What is apixaban?

Answer 16

A DOAC (direct-acting oral anticoagulant).

Question 17

What to know about apixaban, specifically?

Answer 17

CYP 3A4.

Works on Factor 10a. Have to take it twice a day.

Question 18

Do DOACs have food monitoring?

Answer 18

No. Only warfarin.

Question 19

Do DOACs have INR monitoring?

Answer 19

Nope.

Question 20

MOA of DOACs?

Answer 20

Direct inhibition of 2a or 10a.

Question 21

UFH: Unfractionated Heparin, SubQ administration tips.

Answer 21

2in away from belly button
1/2in-5/8in needle, 25/26g.
Don’t ever administer IM.

Question 22

With heparin, why do you monitor platelets and H&H?

Answer 22

For safety reasons. Don’t want bleeding and don’t want HIT. Monitored daily.

Question 23

For heparin, why do you want to measure aPTT?

Answer 23

To make sure it’s at therapeutic levels.

Question 24

How long does HIT take to develop? What is the effect?

Answer 24

5-14 days after heparin exposure.

Thrombosis, thrombocytopenia.

Question 25

What medication do you use to reverse heparin or LMWH od?

Answer 25

Protamine Sulfate, IV over 10m.

Be aware of fish allergy

Question 26

What should we know about low molecular weight heparin?

Answer 26

Less HIT risk.
Longer half-life.
Eliminated really.
No aPTT monitoring.

Question 27

What is Fondaparinux?

Answer 27

Synthetic Unfractionated heparin. 
NO HIT reaction. 
No macrophage/plasma protein binding. 
No monitoring. 
SubQ.

Question 28

What is Bivalrudin?

Answer 28

Inhibitor of thrombin.
IV admin.
Renal elimination.
Good in pts with HIT hx or high bleeding risk.

Question 29

What are SEs of Bivalirudin?

Answer 29

Headache, Hypotension, Pain (back, abdominal, pelvic).

Serious bleeding if combined with other bleeding drugs.

Question 30

What is Argatroban?

Answer 30

Direct thrombin inhibitor. 
IV admin
Hepatic elimination. 
Useful in pts with hx of HIT with an active thrombosis. 
Common to have allergic reactions.