Warfarin

Question 1

How does warfaring work?

How long does it take to work and why?

Answer 1

Vit K antagonist which basically reduces synthesis of clotting factors

A few days as clotting factors have half life up to 80 hours

Question 2

What needs to be checked before starting this medication? - 3

What other clotting test needs to be done?

When should it be done?

Answer 2

FBC
LFT
Coag screen to establish baseline

INR

48 hrs after starting
Daily until in target range
Then weekly/monthly

Question 3

How many days preoperatively should it be stopped?

How many days post operatively should it be stopped?

Answer 3

5 days

48 hrs

Question 4

Contraindications:

• to do with blood
• type of stroke
• happens in stomach and duodenum
• can only happen in women
• to do with BP

Answer 4

Bleeding disease 
Haemorrhagic stroke 
Active PUD 
Pregnancy 
Severe HTN

Question 5

Agents/drugs that raise levels in blood:

• AB’s
• CV
• Psych
• Drug for GORD
• In the RUQ
• Diet and lifestyle

Answer 5

Macrolides
Metronidazole
Ciprofloxacin

Statins
Amiodarone

SSRI’s
Valproate

Omeprazole

Liver disease

Acute alcohol
Grapefruit and cranberry juice

Question 6

Agents/drugs that lower levels in blood:

• Used to treat epilepsy
• Used to treat epilepsy
• Sedative starting with B
• Antibiotic starting with R
• Can binge
• Not good for anything

Answer 6

Phenytoin 
Carbamazepine 
Barbiturates 
Rifampicin 
Chronic alcohol 
Smoking

Question 7

What about aspirin and NSAID’s in conjunction with warfarin?

Answer 7

increases bleeding risk due to their anti-platelet effects

Question 8

Side effects:

• Big one
• GI
• Hepatic
• Skin

Answer 8

Bleeding

N&V
Diarrhoea

Jaundice, hepatitis dysfunciton

Skin necrosis especially with protein C and S deficiency

Question 9

What can be given to reverse warfarin effects?

Answer 9

Vit K IV