Anti Coagulents

Question 1

What is the mode of action of warfarin?

Answer 1

Epoxide reductase inhibitor which stops activation of VitK

Can take up to 5 days to have an effect so should have heparin for this time

Question 2

What are the indications of warfarin?

Answer 2

Mechanical heart valve

Second line in DVT/PE/AF

Question 3

What monitoring is required for warfarin?

Answer 3

INR
-initially done on alternate days after starting until in target INR

Target INR

• DVT/PE/AF= 2-3
• Recurrent DVT/PE or mechanical heart valve= 3-4

Question 4

What should be done if there is over anticoagulation of warfarin?

Answer 4

INR 5-8
-skip dose and restart when INR <5

INR 5-8 and minor bleeding

• stop warfarin and give IV vit K
• restart when INR <5

INR >8

• stop and give oral VitK
• can repeat VitK 24hrs later if INR high still
• restart at lower dose when INR <5

INR>8 and minor bleeding

• stop and give IV VitK
• restat when INR <5

Major bleeding

• stop
• IV vitK and prothrombin complex concentrate (octaplex)

Question 5

When is warfarin contraindicated?

Answer 5

Peptic ulcer disease
pregnancy
Severe HTN

Question 6

What are DOACs?

Answer 6

Apixaban, Rivaroxaban and Dabigatran

A and R are competitive receptor antagonists of factor Xa

D is competitive receptor antagonist for thrombin

Rapid onset of action and no monitoring required

Question 7

What is given with over anticoagulation of DOACs?

Answer 7

For dabigatran can give idarucizmab

Question 8

What are SE and contraindications of DOACs?

Answer 8

Do not give if creatinine clearance <30

Slightly higher risk of GI bleeding

Question 9

What is LMWH?

Answer 9

Enoxaparin
Inhibits factor Xa
No monitoring needed unless severe renal impairment

Lower dose for prophylaxis and higher dose for treatment

Question 10

What is unfractionated heparin?

Answer 10

Given SC or IV
Rapid onset of action and short half life so can be stopped quickly
Used in high bleeding risk
Should measure APTT 6hrs after and aim for 1.5-2.5

Potentiates anti-thrombin III

Question 11

What are side effects and contraindications of heparin?

Answer 11

Contraindicated in bleeding disorders and peptic ulcers

Heparin induced thrombocytopenia
GI bleeding
Osteoporosis
Hyperkalaemia

Less common in LMWH

Question 12

What is given in over anti-coagulation of unfractionated heparin?

Answer 12

Protamine sulphate infusion

Less effective with LMWH

Question 13

What are contraindications of thrombolysis?

Answer 13

Active bleeding
Severe HTN
Recent head trauma
Recent surgery
Pregnancy 
Severe liver disease or oesophageal varices
Prolonged or traumatic CPR