MicroRNA from a 12-h versus 20-h acetylcysteine infusion for paracetamol overdose. 
Paracetamol overdose is common and microRNA (miR)-122 expression is increased with liver injury.  We aimed to measure miR-122 in the setting of an abbreviated paracetamol overdose treatment regimen.  We compared miRNA expression in patients treated for paracetamol poisoning with an abbreviated 12-h intravenous acetylcysteine regimen (200 mg/kg over 4 h, 50 mg/kg over 8 h) or a 20-h regimen (200 mg/kg over 4 h, 100 mg/kg over 16 h) (NACSTOP trial).  miR-122 expression is increased (decreased cycle threshold (Ct) values) with paracetamol liver injury.  We assessed miR-122 expression in patients receiving the two acetylcysteine regimens and in a separate group with acute liver injury (ALI).  We examined 121 blood samples in 38 patients.  After 20 h of acetylcysteine, median alanine transaminase (ALT) was 12 U/L (18, 14) versus 16 U/L (11, 21) ( p = 0.17) and median miR-122 Ct was 30.1 (interquartile range (IQR): 28.9, 33.3) versus 31.4 (28.9, 33.9) ( p = 0.7) in the NACSTOP abbreviated and control groups, respectively.  Median normalized miR-122 Ct after 20 h of acetylcysteine was 2.2 (IQR 1.9, 6.4), 1.1 (0.7, 2.9), 63.9 (2.5, 168), 123.2 (40.9, 207.8) in the NACSTOP-abbreviated, NACSTOP-control, ALI and hepatotoxicity groups, respectively.  There was no significant difference in ALT or miRNA between NACSTOP treatment groups and no signal of increased liver injury from an abbreviated 12-h acetylcysteine regimen.  These findings suggest that an abbreviated acetylcysteine regimen in low-risk patients who have overdosed on paracetamol is safe.  Further study is required to validate this finding utilizing miRNA as a comparative biomarker.