Keywords: acetaminophen, acetylcysteine (PubMed Search)
The three-bag IV acetylcysteine regimen for acetaminophen overdose is complicated and can result in medication/administration errors.  Two recent studies have attempted simplifying the regimen using a two-bag approach and evaluated its effect on adverse effects. [2, 3]
Study 1 
Prospective comparison of cases using a 20 h, two-bag regimen (200 mg/kg over 4 h followed by 100 mg/kg over 16 h) to an historical cohort treated with the 21 h three-bag IV regimen (150 mg/kg over 1 h, 50 mg/kg over 4 h and 100 mg/kg over 16 h).
The two-bag 20 h acetylcysteine regimen was well tolerated and resulted in significantly fewer and milder non-allergic anaphylactic reactions than the standard three-bag regimen.
Study 2 
Prospective observational study of a modified 2-phase acetylcysteine protocol. The first infusion was 200 mg/kg over 4-9 h. The second infusion was 100 mg/kg over 16 h. Pre-defined outcomes were frequency of adverse reactions (systemic hypersensitivity reactions or gastrointestinal); proportion with ALT > 1000 U/L or abnormal ALT.
The 2-phase acetylcysteine infusion protocol resulted in fewer reactions in patients with toxic paracetamol concentrations.
Final word: Two-bag regimens seem to offer advantages compared to the traditional three-bag regimen with regard to reduced adverse drug reactions. Look for more data, particularly on effectiveness, and a potential transition to a two-bag approach in the future.
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