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Abstract

We appreciate the interest by Tsai et al in our study. The administration of less than 72 hours of oral N-acetylcysteine following inappropriate acetaminophen use has clearly been used by many poison centers and members of the medical toxicology community for years.1Kozer E. McGuigan M. Treatment strategies for early presenting acetaminophen overdose: A survey of medical directors of Poison Centers in North America and Europe.Hum Exp Toxicol. 2002; 21: 123-127Crossref PubMed Scopus (12) Google Scholar While a multicentered randomized study remains lacking, our experience with a shortened N-acetylcysteine protocol in addition to those published initially by Woo et al2Woo O.F. Mueller P.P. Olson K.R. et al.Shorter duration of oral N-acetylcysteine therapy for acute acetaminophen overdose.Ann Emerg Med. 2000; 35: 363-368Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar and later by Tsai et al3Tsai C.L. Chang W.T. Weng T.I. et al.A patient-tailored N-acetylcysteine protocol for acute acetaminophen intoxication.Clin Ther. 2005; 27: 336-341Abstract Full Text PDF PubMed Scopus (47) Google Scholar lends evidence supporting the effectiveness of this “off-label” use of shortened duration N-acetylcysteine treatment in a “low risk patient” subset. Our prospective observational study was designed to look solely at those patients that we considered low risk based upon predefined laboratory criteria. Those acute acetaminophen poisonings not meeting these criteria were by default placed in a category of individuals requiring a minimum of 72 hours of treatment. It is unclear to us how the omission in our study of individuals considered “high risk” and requiring continued N-acetylcysteine treatment would have any impact on defining the effectiveness of a shortened treatment regimen in an entirely different patient subset. The point is duly noted, however, that far from all acetaminophen-poisoned patients may be considered acceptable candidates for early N-acetylcysteine discontinuation. A retrospective evaluation of 2 years of California Poison Center data on acetaminophen poisoning found that 817 out of 1339 (61.0%) patients with acute, chronic, or ingestions at an unknown time considered to be possibly toxic would meet our study’s laboratory criteria for early N-acetylcysteine discontinuation.4Betten D.P. Burner E.E. Williams S.R. Clark R.F. A retrospective evaluation of shortened course oral N-acetylcysteine for the treatment of acute acetaminophen poisoning [abstract].Clin Tox. 2005; 43: 87Google Scholar It is our belief that the low number of patients in our study with full laboratory studies recorded prior to N-acetylcysteine discontinuation was in many cases due to inaccurate reporting by treating health care professionals. That being said, it is clear to us that a treatment protocol will only be effective if it is appropriately followed. The use of acetaminophen clearance rates in dictating treatment time holds promise, yet may find similar limitations if clinicians are unable to understand or apply rules for appropriate timing of N-acetylcysteine discontinuation. Many of these clinicians may not be managing acetaminophen-poisoned patients on a regular basis. Guidance from a medical toxicologist or a poison center specialist may help to assure that inappropriately early treatment discontinuation does not occur. Key Features of the Patient-Tailored N-Acetylcysteine ProtocolAnnals of Emergency MedicineVol. 51Issue 4PreviewWe read with great interest the article by Betten et al1 and the accompanying editorial2 on the shortened course oral N-acetylcysteine for the treatment of acute acetaminophen poisoning. We agree with the main results and ideas but feel that there are a few additional points that are worth noting. Full-Text PDF