None of 205 selected patients treated with a shortened course of N-acetylcysteine therapy developed liver injury.
The standard approach to acetaminophen poisoning is an 18-dose oral regimen of N-acetylcysteine given over 72 hours. However, this regimen may prolong an otherwise short hospitalization, and the bad taste of N-acetylcysteine sometimes causes nausea or vomiting.
In a prospective study, researchers from the California poison control system tested a shortened protocol for patients with potentially toxic acetaminophen ingestion. After the initial five doses of N-acetylcysteine (20 hours), the drug could be stopped if the acetaminophen level was undetectable and the AST, ALT, and prothrombin times were normal. If any of these conditions were not met, N-acetylcysteine was continued until the acetaminophen level was undetectable and the lab tests were normal.
Of 282 patients with acute acetaminophen poisoning who were eligible for shortened treatment, 205 actually received it (clinicians treating the other patients preferred to give the standard 72-hour treatment). The mean duration of shortened treatment was 36 hours. None of the 195 patients who were available for follow-up within 30 days after overdose had an adverse hepatic outcome, and none of the remaining 10 patients subsequently appeared in a death index or liver transplant registry.
Comment: Although this trial was not randomized, the findings strongly suggest that an abbreviated course of N-acetylcysteine is acceptable for patients with acetaminophen overdose who meet certain criteria. Editorialists endorse the findings but call for a clinical trial to corroborate them.
Published in Journal Watch General Medicine September 13, 2007
Betten DP et al. A prospective evaluation of shortened course oral N-acetylcysteine for the treatment of acute acetaminophen poisoning. Ann Emerg Med 2007 Sep; 50:272-9.