Adverse reactions in patients treated with the one-bag method of N-acetylcysteine for acetaminophen ingestion

Abstract Acetaminophen (paracetamol) remains the leading pharmaceutical agent in overdoses in North America. The three-bag Prescott protocol for intravenous (IV) acetylcysteine is complex and prone to errors. It has frequent adverse reactions, particularly non-allergic anaphylactoid reactions (NAARs). Over 15 years ago, we adopted a simplified, one-bag protocol using a standard concentration to reduce errors. We report the adverse reactions with this protocol. We used hospital pharmacy records to retrospectively identify patients who received IV acetylcysteine between 12 January 2005 and 20 June 2016. We excluded patients without acetaminophen overdose or with any part of their IV acetylcysteine at an outside hospital. We searched pharmacy records for diphenhydramine or any antiemetic after commencing IV acetylcysteine. We reviewed progress notes for descriptions of nausea, dyspnea, itching/pruritus, or rash. Out of 252 patients receiving IV acetylcysteine, 202 met our inclusion criteria. Thirty-three patients had at least one adverse reaction including nausea in 28 patients and any symptom of NAAR in 8 patients. Twenty-eight patients received an antiemetic. Eleven patients received diphenhydramine (nine for NAAR and two with prochlorperazine). Nausea was the most common adverse reaction. The rate of non-allergic anaphylactoid reactions with the one-bag protocol was 4%.