Paracetamol Overdose

Question 1

What does the liver conjugate paracetamol with ?

Answer 1

Glucoronic or sulphate

Question 2

During paracetamol over dose what happens in the liver system

Answer 2

Conjugation system in the liver becomes OVER SATURATED

Question 3

What happens to the paracetamol when the B conjugation system in the liver becomes over saturated ?

Answer 3

Paracetamol oxidises using the P450
Producing toxic - N acetyl b benzoquinone

Question 4

How does glutathione help with the N acetyl B benzoquinone

Answer 4

Glutathione helps to congugate the toxic substance made forming non toxic mercapturic acid
However glutathione stores run out q

Question 5

When glutathione runs out how does the toxin damage the body

Answer 5

Forms covalent bonds proteins denaturing them not just liver cells but renal cells

Question 6

How does N acetyl cysteine help with paracetamol overdose

Answer 6

Pre cursor to glutathione - can increase hepatic glutathione production to counteract the paracetamol over oxidation

Question 7

The following groups of patients are at an increased risk of developing hepatotoxicity following a paracetamol overdose ?

Answer 7

Patients taking liver enzyme-inducing drugs - rifampicin, phenytoin,
carbamazepine,
St John’s Wort

Patients with a history of chronic alcohol excess

Malnourished patients (e.g. anorexia nervosa) or patients who have not eaten for a few days, due to depletion of glutathione.