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N-Acetylcysteine

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N-Acetylcysteine, Acetylcysteine, Acetadote, Mucomyst, NAC

  • Indications
  • Established
  1. Acetaminophen Overdose
  2. Contrast-Induced Nephropathy prevention
  • Indications
  • Evolving
  1. Prevention of COPD Exacerbation
    1. Dose: 600-1200 mg/day in divided dosing
    2. Decramer (2005) Lancet 365(9470):1552-60 [PubMed]
  2. Idiopathic Pulmonary Fibrosis
    1. Dose: 1800 mg/day in divided dosing
    2. Demedts (2005) N Engl J Med 353(21):2229-42 [PubMed]
  • Mechanism
  1. N-Acetylcysteine increases glutathione levels
    1. Acts as detoxification agent
    2. Acts as antioxidant
  2. N-Acetylcysteine increases nitric oxide concentrations
    1. Stimulates vasodilation
  • Adverse Effects (uncommon at doses 1200 mg/day or less)
  1. Nausea
  2. Vomiting
  3. Diarrhea
  4. Anaphylactoid Reaction (8% with IV)
    1. Contact poison control for rate adjustment in Acetaminophen Overdose
    2. Stop infusion for severe reactions (deaths have occurred)
  • Safety
  1. Pregnancy: Category B
  1. Protocol
    1. See Acetaminophen Overdose
    2. Directed by Rumack-Matthew Acetaminophen Nomogram
      1. http://www.ars-informatica.ca/toxicity_nomogram.php?calc=acetamin
    3. Continue NAC beyond protocol below if any of the following persist at end of protocol
      1. High Acetaminophen level or
      2. Increasing Bilirubin, INR or transaminases
  2. Formulation
    1. Intravenous indications
      1. Fulminant hepatic failure (best studied)
      2. Pregnancy
      3. Intractable Vomiting
    2. Oral advantages
      1. Preferred route
      2. Cheap and effective
      3. Lower Incidence of anaphylactoid reaction than with IV form
  3. Adults
    1. Oral
      1. Load: 140 mg/kg orally for 1 dose
      2. Next 70 mg/kg every 4 hours for total of 17 doses
      3. Administration pearls
        1. Better tolerate when chilled or mixed with orange juice or soda
        2. NAC smell may decrease tolerability (consider placing in covered cup with straw)
        3. Vomiting
          1. Re-dose if vomits within one hour of dose
            1. No need to re-dose if Vomiting after one hour (Absorbed quickly)
          2. Consider concurrent Ondansetron (Zofran) or other Antiemetic
          3. Consider switching to intravenous NAC
    2. Intravenous
      1. Load: 150 mg/kg in 200 ml D5W IV over 1 hour for 1 dose
      2. Next: 12.5 mg/kg/hour for 4 hours (50 mg/kg in 500 ml D5W given over 4 hours)
      3. Next: 6.25 mg/kg/hour for 16 hours (100 mg/kg in 1000 ml D5W given over 16 hours)
        1. May be extended for ongoing hepatotoxicity until Liver Function Tests start improving
  4. Child
    1. Oral: Same as for adults
    2. IV: Same as for adults
      1. EXCEPTION: For <88 lb (40 kg), dilute to 40 mg/ml in D5W
      2. Smaller volume to prevent Hyponatremia
  • References
  1. Nordt and Swadron in Majoewsky (2013) EM:Rap 13(4): 10-11
  2. Rowden (2006) Clin Lab Med 26(1): 49-65 [PubMed]
  3. Sung (1997) Pediatrics 100(3 pt 1): 389-91 [PubMed]