Criteria for acetylcysteine treatment and clinical outcomes after paracetamol poisoning

Abstract

Acetylcysteine is an effective antidote for paracetamol (acetaminophen) poisoning, but different treatment criteria exist internationally. In the UK, acetylcysteine is indicated by paracetamol concentrations higher than the Prescott nomogram or higher than 50% of the nomogram in patients with increased susceptibility to liver toxicity. In the USA, a single ‘150-line’ nomogram has been used that removes the need for additional clinical risk assessment. The latter approach has recently been adopted in Australia, New Zealand and elsewhere. Few data exist to allow direct comparison of these different international approaches. An existing database of 1191 patients admitted to hospital after paracetamol overdose identified that the 4-h equivalent paracetamol concentration was: ≥200 mg/l in 163 patients (15.6%; 95% CI: 13.3–18.2%), ≥150 mg/l in 264 (24.3%; 95% CI: 21.5–27.5%) and ≥100 mg/l in 426 patients (39.3%; 95% CI: 35.6–43.2%), and acute liver injury occurred in 3.7% (95% CI: 1.4–8.0%), 2.3% (95% CI: 0.8–5.0%) and 1.9% (95% CI: 0.8–3.7%), respectively. The different indications for acetylcysteine used by the UK and USA would result in similar numbers of patients treated, although the criteria would define patients with different characteristics and patterns of overdose. The relative merit of these different international approaches to acetylcysteine administration is considered in this article.

Keywords::

• acetylcysteine
• acetaminophen
• antidote
• drug toxicity
• liver injury
• nomogram
• paracetamol
• poisoning
• risk assessment

Acknowledgements

The data were originally collected by the author when he worked as a Consultant in the Poisons Unit & Acute Medical Unit of the Royal Infirmary of Edinburgh. The author had sole responsibility for the study design, submission for consideration by the Ethics Committee and Research and Development department, data analyses and report writing. The author is grateful to Margaret Dow and Janice Pettie of the Poisons Unit of the Royal Infirmary of Edinburgh for assistance with the original data collection, and would like to acknowledge the medical and nursing staff of the Emergency Department and Poisons Unit of the Royal Infirmary of Edinburgh for their clinical care of the patients.

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.