Paracetamol Overdose

Question 1

WHo is at increased risk of hepatotoxicity following paracetamol overdose?

Answer 1

• those taking liver enzyme inducing drugs ( rifampicin, phenytoin, chronic alcohol excess, st john’s wort, carbamazepine
  -malnourished patients

Question 2

if patients present within 1 hour of overdose they may benefit from?

Answer 2

activated charcoal to reduce absorption of the drug

Question 3

acetylcysteine should be given if?

Answer 3

1. the plasma paracetamol concentration is on or above a single treatment line joining points of 100 mg/L at 4 hours and 15 mg/L at 15 hours, regardless of risk factors of hepatotoxicity

2.there is a staggered overdose* or there is doubt over the time of paracetamol ingestion, regardless of the plasma paracetamol concentration; or

3. patients who present 8-24 hours after ingestion of an acute overdose of more than 150 mg/kg of paracetamol even if the plasma-paracetamol concentration is not yet available
4. patients who present > 24 hours if they are clearly jaundiced or have hepatic tenderness, their ALT is above the upper limit of normal
   acetylcysteine should be continued if the paracetamol concentration or ALT remains elevated whilst seeking specialist advice

Question 4

how much time is acetylcysteine infused over?

Answer 4

1 hour

Question 5

what does acetylcysteine commonly cause?

Answer 5

anaphylactoid reaction (non-IgE mediated mast cell release)

Question 6

how to stop an anphylactoid reaction to IV acetylycysteine?

Answer 6

stopping the infusion, restart at slower rate

Question 7

liver transplantation criteria after paracetamol liver failure?

Answer 7

arterial pH< 7.3 , 24 hours ingestion

or all of the following:
prothrombin time> 100 seconds
creatinine> 300 micromol/l
grade III or IV encephalopathy