(473) IV N-Acetylcysteine for Non-Acetaminophen-Induced Acute Liver Failure

Introduction: The American Association for the Study of Liver Diseases (AASLD) suggests that IV N-acetylcysteine (NAC) may have benefit in patients with Non-Acetaminophen Induced Acute Liver Failure (NAI-ALF). Some studies suggest that using IV NAC in the setting of NAI-ALF improved transplant free survival in patients with Grade I-II encephalopathy compared to placebo while others suggest there is no benefit. Variability in dosing and duration make it difficult to assess the true benefit of IV NAC for this indication. The dose utilized at Rush University Medical Center is 150mg/kg over 1 hour, 50mg/kg over 4 hours and 6.25mg/kg/hour for 67 hours or until discontinued. The objective of this case series was to identify clinical markers to assess efficacy and guide duration of therapy of IV NAC for NAI-ALF.

Methods: Adult patients who received at least one dose of IV NAC for NAI-ALF were included. Patients treated for acetaminophen toxicity, started IV NAC therapy at an outside hospital, and less than the age of 18 were excluded. Patient charts were retrospectively reviewed to collect data on survival, receipt of liver transplant, and daily lab values for alanine transaminase (ALT), aspartate aminotransferase (AST), and international normalized ratio (INR).

Results: Eighty-two patients were identified with 49 patients analyzed after applying exclusion criteria. The most common etiology for liver failure was ischemic liver injury in 16 patients (33%) and empiric therapy in 28 patients (61%) without an identifiable cause at presentation. Of those patients, 10 (36%) were later identified to have ischemic liver injury as the mechanism for ALF. Patients received NAC for a median duration of 28 hours. The median age for this cohort was 54 years and most patients had a MELD score between 31-40 (41%). Twenty-five (51%) patients survived to day 28 after presentation. Overall, INR tended to normalize on day 4 after administration of IV NAC, and AST and ALT normalized on day 2 after administration.

Conclusions: It is difficult to conclude whether duration of IV NAC therapy can be guided with liver function tests or if IV NAC improves survival due to the high mortality rate in this study. Prospective trials are needed to determine the utility of IV NAC for NAI-ALF.