In this episode, I’ll discuss N-acetylcysteine in non-acetaminophen-induced acute liver failure.
Treatment of acute liver failure with N-acetylcysteine is the first thing that comes to mind if the liver failure is due to acetaminophen. However acute liver failure from causes other than acetaminophen may also respond to treatment with N-acetylcysteine. A recent meta-analysis evaluated 5 prospective studies that included 672 patients with acute liver failure who were split between a control group and treatment with N-acetlycysteine. The most common causes of acute liver failure were: viral hepatitis, drug-induced (but not from acetaminophen), auto-immune hepatitis and cause indeterminate.
55% of the patients in the N-acetylcysteine group had transplant-free survival compared with just 28% in the control group. The relative risk in favor of treatment was 0.56. Treatment also was responsible for a lower length of hospital stay when compared to control. While overall survival was numerically superior in the treatment group, this difference was not statistically significant.
N-acetylcysteine was given as an IV infusion in 4 of the studies and orally in the 5th. Most patients had treatment that lasted 72 hours. The most commonly studied regimen was an initial loading dose of 150 mg/kg/hr of N-acetylcysteine over one hour, followed by 12.5 mg/kg/hour for 4 hours, then continuous infusions of 6.25 mg/kg N-acetylcysteine for the remaining 67 hours. Only 1 of the 5 studies suggested an increase in adverse events with treatment, and this was only nausea and vomiting related events.
While the total number of patients is relatively small, the authors of the meta-analysis are confident these 5 studies represent all of the available published data on the topic. With there being seemingly no downside risk to the administration of N-acetylcysteine, it is reasonable to consider this therapy in acute liver failure, even if acetaminophen is not the cause.
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