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Safety and Efficacy of the SNAP 12-hour Acetylcysteine Regimen for the Treatment of Paracetamol Overdose

Lookup NU author(s): Dr Ruben ThanacoodyORCiD, Professor Simon ThomasORCiD



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Background Acetylcysteine (NAC) is effective at preventing liver injury after paracetamol overdose. The Scottish and Newcastle Anti-emetic Pre-treatment for Paracetamol Poisoning (SNAP) Study demonstrated that a 12h NAC regimen was associated with fewer adverse drug reactions compared with the standard 21h regimen. Here, we describe the clinical effectiveness of the SNAP NAC regimen. Methods The SNAP regimen, consisting of intravenous NAC 100mg/kg over 2h then 200 mg/kg over 10h, was introduced to treat all paracetamol overdose patients at the Royal Infirmary of Edinburgh, the Royal Victoria Infirmary, Newcastle and St Thomas’ Hospital, London. Patient data were prospectively and systematically collected before and after the change in treatment (total patients N= 3340, 21h N=1488, SNAP N=1852). Health record linkage was used to determine patient outcome after hospital discharge. Findings There was no difference in liver injury or liver synthetic dysfunction between regimens. Hepatotoxicity (peak ALT>1000U/L) occurred in 64 (4.3%) and 67 (3.6%) patients, respectively, in the 21h and SNAP groups (absolute difference -0.7%, 95% CI -2.1 to 0.6). Multivariable logistic regression did not identify treatment regimen as an outcome-associated factor. No patients were readmitted to hospital with, or died from, liver failure within 30 days of discharge. Anti-histamine treatment (for NAC anaphylactoid drug reactions) was prescribed for 163 (11.0%) patients with the 21h regimen and 37 (2.0%) patients with the SNAP regimen (absolute difference 9.0% (95% CI 7.3 to 10.7)). Interpretation In clinical use the SNAP regimen has similar efficacy as standard therapy for preventing liver injury and produces fewer adverse reactions.

Publication metadata

Author(s): Pettie JM, Caparrotta TM, Hunter RW, EMorrison EE, David M Wood DM, Dargan PI, Thanacoody RH, Thomas SHL, Elamin MEMO, Francis B, Webb DJ, Sandilands EA, Eddleston M, Dear JW

Publication type: Article

Publication status: Published

Journal: EClinicalMedicine

Year: 2019

Volume: 11

Pages: 11-17

Online publication date: 02/05/2019

Acceptance date: 10/04/2019

Date deposited: 11/04/2019

ISSN (electronic): 2589-5370

Publisher: Elsevier Ltd


DOI: 10.1016/j.eclinm.2019.04.005


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