A 28-year-old woman is brought to the emergency department 6 hours after ingesting approximately 15 g of paracetamol in a suicide attempt. She is currently asymptomatic with normal vital signs. Physical examination is unremarkable. Blood investigations show: AST 45 U/L, ALT 52 U/L, bilirubin 0.9 mg/dL, INR 1.0, serum paracetamol level 180 µg/mL. What is the most appropriate next step in management?