Management of Anaphylactoid Reactions to Intravenous N-Acetylcysteine☆,☆☆,★,★★,♢
Section snippets
INTRODUCTION
N-Acetylcysteine (NAC) is an effective antidote for acute acetaminophen poisoning.1 It is usually given orally in a 72-hour treatment protocol or intravenously in either a 20-hour or a 48-hour treatment protocol.1 When used intravenously, NAC can cause anaphylactoid reactions involving flushing, urticaria, angioedema, bronchospasm, and other respiratory symptoms or a combination of them.1
In no study has the management of these reactions and the continuation of intravenous NAC been assessed.
Phase 1: Retrospective study and guidelines development
We reviewed the charts of all patients hospitalized in our pediatric hospital with a diagnosis of acetaminophen overdose between January 1, 1990, and December 31, 1995, to identify adverse reactions to intravenous NAC and the treatment used. In an attempt to detect all reactions, we reviewed medical progress notes, nursing progress notes, and medication prescription and delivery forms. Adverse reactions to NAC were defined as the presence of symptoms or signs of anaphylactoid reactions.
Phase 1: Retrospective study and guidelines development
Over the 6 years studied, 60 patients received at least one dose of NAC (more than one protocol was sometimes carried out in the same overdose). Forty-three patients were exposed to at least the first and the beginning of the second infusion of the 20-hour intravenous-NAC protocol, 5 patients were exposed at least to the first dose of the 48-hour intra venous-NAC protocol, and 16 patients were exposed to the first dose of the 72-hour oral-NAC protocol.
Adverse reactions to NAC developed in 11
DISCUSSION
Most adverse reactions to NAC are said to be anaphylactoid in nature because the reaction is clinically similar to an anaphylactic reaction in that it is caused by release of histamine but generally not IgE-mediated. Very rarely these reactions may have been associated with hypotension and death.7, 16, 19 The role of NAC in the reported deaths is not clear: In all of them an alternative cause of death was possible. Furthermore, in three of four, an incorrect dose of NAC was administered.7, 16,
Acknowledgements
We thank all the poison-information specialists who identified cases.
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Cited by (0)
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From the Section of Clinical Pharmacology and Toxicology* and Emergency Section,‡ Department of Pediatrics, Hôpital Sainte-Justine, Montreal, Quebec; and the Division of Clinical Pharmacology and Toxicology, Department of Pediatrics, Hospital for Sick Children and the Ontario Regional Poison Information Centre, Toronto, Ontario, Canada.§
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Received for publication April 9, 1997. Revisions received July 28, 1997, and January 28, 1998. Accepted for publication February 26, 1998.
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Dr Bailey was supported by a fellowship from the R. Samuel McLaughlin Foundation and the Canadian Society for Clinical Pharmacology.
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Address for reprints: Benoit Bailey, MD, MSc, Department of Pediatrics, Hôpital Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec, H3T 1C5 , Canada
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