A 25-year-old woman presents 6 hours after ingesting 20 g of immediate-release paracetamol in a suicide attempt. She weighs 60 kg. She is asymptomatic. Her 4-hour post-ingestion paracetamol level is 180 mg/L (1190 µmol/L). According to Australian paracetamol poisoning guidelines, what is the most appropriate management?