Intravenous acetaminophen associated with acute liver failure

Abstract

In conjunction with BMJ Case Reports, DTB will feature occasional drug-related cases that are likely to be of interest to readers. These will include cases that involve recently marketed drugs for which there is limited knowledge of adverse effects and cases that highlight unusual reactions to drugs that have been marketed for several years. A woman in her mid-60s, without known liver disease, was admitted to the hospital with a partial malignant colonic obstruction. Over a 6-day course, she received a total of 13 g of intravenous acetaminophen not exceeding 4 g over a 24-hour period. She developed encephalopathy and an international normalised ratio of 6.1 meeting criteria for acute liver failure (ALF). She was treated with intravenous N-acetyl cysteine and other causes of liver failure were excluded. The patient was discharged with subsequent resolution of encephalopathy and improvement of her liver chemistries. Though ALF is rare, in countries where acetaminophen is readily available, almost 50% of ALF cases are acetaminophen-induced hepatotoxicity and most have been documented as oral ingestion of acetaminophen. We present a rare case of intravenous acetaminophen-induced ALF. Acute liver failure (ALF) is defined as new onset coagulopathy with international normalised ratio (INR) ≥1.5 and encephalopathy without pre-existing cirrhosis.1 Drug-induced liver injury (DILI) is the most common cause of ALF in the USA occurring at a rate of 20 cases per 100 000 persons.2 3 Of all DILI cases, acetaminophen-induced hepatotoxicity accounts for up to 46% of ALF cases.2 The two main aetiologies of acetaminophen overdoses are either intentional, often in context of suicide attempts, and unintentional overdoses, also known as therapeutic misadventures.3 4 Bower et al conducted a population-based surveillance for ALF that noted 55% of all acetaminophen-related ALF cases to be therapeutic misadventures.5 Current US Food and Drug Administration packaging …