Drug overdose

Question 1

Groups at increased risk of developing hepatotoxicity following paracetamol OD

Answer 1

Patients taking liver enzyme-inducing drugs

Malnourished patients or patients who have not eaten for a few days

Question 2

Liver enzyme-inducing drugs

Answer 2

Rifampicin

Phenytoin

Carbamazepine

Chronic alcohol excess

St John’s Wort

Question 3

First treatment if within 1 hour of ingestion

Answer 3

Activated charcoal to reduce absorption of the drug

Question 4

When to give NAC

Answer 4

If paracetamol conc > single treatment line regardless of risk factors of hepatotoxicity

Staggered overdose

Patients who present 8-24 hours after ingesting ?150mg/kg

Patients who present >24 hours and clearly jaundiced or have hepatic tenderness or ALT is high

Question 5

NAC

Answer 5

Infused over 1hour

Commonly causes anaphylactoid reaction (non IgE mediated mast cell release)

Treat anaphylactic reactions by stopping infusion and restarting and slower rate

Question 6

King’s College Hospital criteria for liver transplant

Answer 6

Arterial pH <7.3 24h after ingestion

or all 3
- PT >100secs
- creatinine >300umol/l
- grade III or IV encephalopathy