Anticoagulants

Question 1

Unfractioned heparin - use?

Answer 1

Enhances antithrombin III activity
Inactivates Xa & thrombin

Monitor with aPTT as unpredictable

Better for renal failure

Question 2

Low molecular weight heparin

Answer 2

Dalteparin, Enoxaparin
(Fondaparinux - synthetic derivative of LMWH)

DVT/PE, Safe in pregnancy too

Enhances antithrombin III activity
Inactivates Xa only

Question 3

What drug can reverse the effects of heparin?

Answer 3

Protamine Sulphate i.v.

Question 4

Warfarin

Answer 4

Vit K antagonist

Prevents hepatic synthesis of active vit K dependent clotting factors (II, VII, IX, X)
Inhibits VK epoxide reductase (VKOR)

Slower onset then heparin

Question 5

Warfarin DDis and contraindications?

Answer 5

Teratogenic
Stop 3 days before surgery and replace with LMWH (48hr half life)

NSAIDS -Displace warfarin from albumin

CYP2C9 inducers (Phenytoin/rifampacin/st john’s wort) - ^metabolism / reduce INR

CYP2C9 inhibitors (amiodarone/clopidogrel) - reduce metabolism / ^ INR

Cephalosporin - reduce vit K so ^warfarin effect

Question 6

What drug can be used to reverse the effects of warfarin?

Answer 6

Prothrombin Complex Concentrate i.v.

Question 7

Direct Oral Anti-coagulant (DOAC)

Answer 7

Apixaban, Edoxaban, Rivaroxaban

Inhibit free bound Xa + Xa bound to antithrombin III

Can’t use in pregnancy/breastfeeding

Question 8

What drug do you give to reverse the effects of apixaban?

Answer 8

Andexanet