Anticoagulants

Question 1

Heparin

Answer 1

MOA: potentiates antithrombin -> dec conversion of prothrombin to thrombin
ROA: SQ or IV
T1/2: 1-2 hrs IV
Renal adj: none
Monitoring: anti Xa (0.3-0.7 goal), Hgb, Hct, Plt
Pearls:
- higher body weights may require higher dosing
- workhorse in hospital, rare outpatient

Question 2

Low Molecular Weight Heparin (LMWH)

Answer 2

MOA: inactivates factor Xa AND decreases transformation from prothrombin to thrombin
ROA: SQ
T1/2: 12hrs
Renal adj: CrCl < 30
Monitor: Hgb, Hct, Plt, SCr
Pearls:
- monitor Xa in obese, renal dysfunction, or pregnant patients
- common in hospital, can be given outpatient

Question 3

Warfarin

Answer 3

MOA: vitamin K antagonist
ROA: oral
T1/2:20-60 hrs
Renal adj: none
DDI: Amiodarone, Macrolide abx, -azole antifungals, sulfa antibiotics, rifampin
Monitor: INR (goal 2-3), Hgb, Hct, Plt
Pearls:
- limit servings of vitamin K rich foods to 3-4 per week

Question 4

Apixaban (Eliquis)

Answer 4

MOA: Factor Xa inhibitor
ROA: oral
Dose:
- Afib 5mg BID
- VTE 10 mg BID x 1 week, then 5mg daily
T1/2: 12hrs
Monitor: Hgb, Hct, Plt, Scr
Pearls:
- best DOAC in pts with poor renal function / ESRD dialysis

Question 5

Apixaban (Eliquis) renal adjustments

Answer 5

In Afib patients:
adjust dose to 2.5mg BID if 2 out of 3 criteria met:
- SCr > 1.5
- Weight < 60 kg
- Age > 80 yrs

Question 6

Rivaroxaban (Xarelto)

Answer 6

MOA: Factor Xa inhibitor
ROA: oral
Dose:
- Afib 20 mg daily
- VTE 15mg BID x 21d then 20 mg daily
T1/2: 5-9h
Monitoring: Hgb, Hct, Plt, SCr
Pearls:
- best studied DOAC in obese patients

Question 7

Rivaroxaban (Xarelto) renal adjustments

Answer 7

Afib:
CrCl 15-50 mL/min: 15mg daily
CrCl < 15 mL/min: AVOID USE

Question 8

Edoxaban (Savaysa)

Answer 8

MOA: Factor Xa inhibitor
ROA: oral
Dose:
- Afib 60mg daily
- VTE (after 5 days parenteral): >60kg - 60mg daily, </=60kg - 30 mg daily
T1/2: 10-14 hrs
Monitor: Hgb, Hct, Plt, SCr
Pearls: rarely used

Question 9

Edoxaban (Savaysa) renal adjustments

Answer 9

Only use in pts with CrCl 15-95 mL/min
Afib: 15-50 mL/min = 30 mg daily

Question 10

Fondaparinux (Arixtra)

Answer 10

Factor Xa inhibitor
ROA: SQ and IV
T1/2: 17-21 hrs
Renal adj: avoid use CrCl < 30
Monitor: Hgb, Hct
Pearls:
- does not contain pork
- avoid weight < 50 kg

Question 11

Dabigatran (Praxada)

Answer 11

MOA: direct thrombin inhibitor
ROA: oral
Dose:
- Afib 150mg BID
- VTE (after 5d parenteral) 150mg BID
T1/2: 12-17hrs
Monitoring: Hgb, Hct, Plt, SCr
Pearls:
- increased risk of GI bleeds compared to warfarin -> rarely used