A 29-year-old man presents to the emergency department 2 hours after ingesting approximately 40 paracetamol 500 mg tablets in an impulsive act of self-harm. He weighs 80 kg and is currently asymptomatic. Serum paracetamol level at 4 hours post-ingestion is 250 mg/L. According to Australian toxicology practice, what is the most appropriate management?