PARACETAMOL OVERDOSE

MANAGEMENT

Airway protection (intubation) (if sedated or no-gag reflex)

Charcoal (give ASAP)

Indications:

• Ingestion < 8 hrs and Dose > 150mg/kg (>10-15g = > 20-30 500mg tablets)
• Chronic ingestion

Dose:

• 50g/150ml water with Sorbitol 50% 150ml

Adverse Reaction:

• Pulmonary aspiration
• Bowel obstruction

(NGT if unco-operative, intubate if airway not protected)

Lavage

Indications:

• Unwilling to take charcoal
• Unable to take charcoal

(intubate if airway not protected)

N-Acetylcysteine (NAC)

Indications: (Any of the following)

by clinical findings

• Signs of hepatic failure (even 24 hrs post-ingestion)

by dose

• Dose > 150 mg/kg and ingestion > 8 hrs ago
• Dose > 150mg/kg and paracetamol level not available within 8 hrs
• Chronic ingestion  > 150mg/kg/24hrs

by Paracetamol level

• 4 hr Paracetomol level > 1300 umol/L (200mg/L)
• 8 hr Paracetomol level > 660 umol/L (100mg/L)
• 12 hr Paracetomol level > 330 umol/L (50mg/L)
• Prolonged metabolism (calculated from two sequential levels)

N.B. For HIV, malnutrition, chronic ethanol intake, anticonvulsant (phenytoin, carbamazepine, phenobarbitone, primidone) use, rifampicin use: Lower the threshold cut off levels e.g. 4, 8, 12 hrly = 660, 330, 165 umol/L

Contraindications:

• Pregancy (relative)
• Asthma (relative)

Adverse Reactions:

see also Treatment of anaphylaxis

• Flushing (no treatment required)
• Urticaria
• Angioedema (hold NAC and review indications)
• Bronchospasm (hold NAC, consider continuing at slower rate)
• Anaphylactoid (dose and rate dependent)

Administration and dose

Standard protocol (20 hr infusion)

150mg/kg in 200 ml 5% Dextrose over 1 hr 50mg/kg in 500 ml 5% Dextrose over 4 hr 100mg/kg in 1000 ml 5% Dextrose over 16 hr

• Can be given > 24 hours in severe toxicity or awaiting transplant (or until INR normal, AST/ALT normal, paracetomol level neglible)

Modified protocol (> 24 hr infusion)

150mg/kg in 200 ml 5% Dextrose over 1 hr 50mg/kg in 500 ml 5% Dextrose over 4 hr 150mg/kg in 1000 ml 5% Dextrose over 24 hr

When to terminate NAC infusion early:

• Treatment onset 8-15 hrs post ingestion: if paracetamol level is non-toxic
• Treatment onset 15-24 hrs/Chronic ingestion: if asymptomatic AND LFTS normal AND Paracetamol < 70 umol/L (10mg/L) at 24 hours
• Unknown ingestion but no evidence of prolonged metabolism

Repeat LFTs after infusion

Vitamin K (only if INR prolonged)

FFP/Clotting factors (only if active bleeding)

PROGNOSIS

Poor

• Treatment delay > 12 hrs
• see disposition for indications for referral to liver transplant centre