Anticoagulant drugs

Question 1

Heparin vs Warfarin

Answer 1

Heparin:
IV or SQ
Short half life
Rapid onset of action
OD reversal: protamine sulfate

Warfarin:
Oral
Long half life
Slow onset of action 2-3 days, 5 days to stabilize
OD reversal: oral or IV vit K (IV small risk of anaphylaxsis, not more effective than oral)
Prothrombin complex concentrate (PCC) or FFP

Question 2

Heparin

Answer 2

Cofactor for activation of antithrombin
Very shoft half life
Can be used in pregnancy, does not cross placenta

Monitor PTT

SE:
Bleeding
Bone loss – decreased bone formation -> osteoporosis
Heparin induced thrombocytopenia (HIT)

Question 3

Heparin induced thrombocytopenia (HIT)

Answer 3

Binds platelet factor 4
Auto Ab – heparin – PF4 complex -> activate platelets -> aggregate, removed from circulation and destroyed
-> thrombocytopenia
-> hypercoagulable state

Tx: stop heparin
Start different anticoagulant

Question 4

Direct thrombin inhibitors

Answer 4

USE: HIT or contra for heparin

Derivatives of hirudin (in leech saliva)

• Lepirudin
• bivalirudin
• desirudin

acts at antithrombin site

Argatroban
Dabigatran

Question 5

LMW Heparins

Answer 5

Enoxaparin
Dalteparin
Not interchangeable

Stimulate antithrombin to inactivate Xa instead of thrombin

Longer half life

SQ:
QD prophylaxis
BID tx DVT

Doesn’t have to be monitored – wt based dosing

Monitor antifactor Xa activity

Question 6

Fondaparinux

Answer 6

Activates antithrombin

Inhibits Factor Xa

Question 7

Direct factor Xa inhibitors

Answer 7

Rivaroxaban
Apixaban

Tx afib, post op DVT

Question 8

Thrombolytics

Answer 8

Clot busting drugs

Streptokinase
Urokinase
tPA – alteplase

activate plasmin -> degradation of fibrin

use:
early STEMI if no cath lab
acute stroke – early if candidate

Contra:
Active bleeding
Hx intracranial bleed
Recent surgery
Known bleeding disorder
Severe HTN

Reversal agent: aminocaproic acid