Do not get a serum acetaminophen level less than 4 hours after an acute ingestion

4 out of 5 stars Can a serum acetaminophen concentration obtained less than 4 hours post-ingestion determine which patients do not require treatment with acetylcysteine? Yarema MC et al. Clin Toxicol 2017 Feb;55:102-108. Abstract For decades the decision whether or not to treat acute acetaminophen [APAP] toxicity with N-acetylcysteine (NAC) has been guided by a serum APAP level drawn 4 or more hours after ingestion. The thought was that before 4 hours the level might be misleading because absorption of the drug might not be complete. This paper addresses the question of whether an earlier level can be sufficient to clear a patient and decide that the antidote is not needed. The authors performed a secondary analysis of patients entered into the Canadian Acetaminophen Overdose Study over the years 1980 to 2005. They identified nearly 2500 cases in which a patient had an APAP level obtained less than 4 hours after acute ingestion and a second level obtained between 4 and 20 hours post-ingestion. Acute ingestion was defined as one occurring over a duration of less than 4 hours, and “time of ingestion” was taken at the midpoint of that span. The main outcome was agreement between a < 4 hour APAP level of 100 μg/ml or more (pre-specified) and a subsequent > 4 hour level above the treatment line on the Rumack-Matthew nomogram. Long story short, the authors found that: While agreement was very good, the diagnostic accuracy for predicting a subsequent concent...
Source: The Poison Review - Category: Toxicology Authors: Tags: Medical acetaminophen antidote APAP N-acetylcysteine rumack-matthew nomogram treatment Source Type: news