Paracetamol overdose — risk assessment and NAC OSCE

Candidate instructions^[1]

Assess the overdose, start NAC, manage a mild infusion reaction, and arrange psychosocial assessment.^[1]

Candidate tasks^[1]

1. Confirm time, dose (mg/kg), co-ingestants, intent.
2. Interpret need for NAC from timed level.
3. Prescribe three-bag IV NAC with doses.
4. Manage anaphylactoid reaction without abandoning NAC.
5. Refer for mental-health/risk assessment before discharge planning.^[1]

Examiner checklist^[1]

• Toxic dose concept (≥150 mg/kg — 92.6 percent sensitive against the treatment line)^[1]
• NAC indicated; nearly 100% protective if <8 h
• Correct loading and maintenance concept
• Anaphylactoid ≠ true allergy; slow/restart after antihistamine
• LFTs/INR monitoring plan
• Psychosocial assessment mandatory

Model standard^[1]

Start NAC promptly for above-line levels; continue through minor anaphylactoid reactions after treatment (8.2 percent of courses; mostly cutaneous; do not abandon);^[2] monitor for hepatotoxicity; never discharge without psychiatric risk assessment.

Common errors^[1]

• Waiting for ALT rise before NAC
• Stopping NAC permanently after flush/urticaria
• No psych review

References2ShowHide

1. [1]Smilkstein MJ, Knapp GL, Kulig KW, Rumack BH. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. N Engl J Med, 1988.PMID 3059186
2. [2]Yarema M, Chopra P, Sivilotti MLA, et al. Anaphylactoid Reactions to Intravenous N-Acetylcysteine during Treatment for Acetaminophen Poisoning. J Med Toxicol, 2018.PMID 29423816