N-Acetylcysteine
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General
N-acetylcysteine (NAC) prevents toxicity by limiting the formation of NAPQI which increases the ability to detoxify the NAPQI that is formed via hepatotoxic substances such as tylenol.
- Type:
- Dosage Forms:, IV, PO, Nebulized
- Common Trade Names: NAC;
Adult Dosing
Acetaminophen (tylenol) toxicity
PO
- 140mg/kg PO load
- 70mg/kg PO q4hr x17 doses additional; dilute to 5% soln
IV
- Loading dose: 150mg/kg in 100 mL D5W over 60min
- Second (maintenance) dose: 50mg/kg in 250 mL D5W over 4hr
- Third dose: 100mg/kg in 500 mL D5W over 16hr
Comments
- Almost 100% effective if given <8 hr post-ingestion; less effective if 16-24 hr post-ingestion
- May still be useful >24 hr post-ingestion, even with fulminant hepatic failure. Give NAC until LFTs improve (not until APAP level is 0) [1] [2]
- Be aware NAC treatment may affect PT. May see a dose-dependent increase in PT following NAC in patients without hepatotoxicity. [3]
Pediatric Dosing
Special Populations
- Pregnancy Rating:
- Both IV or oral NAC may be used in pregnant patients with Acetaminophen toxicity. [4]
- IV formulation may be preferred to increase fetal NAC concentrations
- Lactation:
- Renal Dosing
- Adult
- Pediatric
- Hepatic Dosing
- Adult
- Pediatric
Contraindications
- Allergy to class/drug
Adverse Reactions
Serious
- Anaphylactoid reaction but also associated with seizures, cerebral edema, & herniation. [5]
- Anaphylaxis responds to standard therapies and can usually restart NAC without safely without complications. [6]
- No treatment is necessary for isolated flushing
- If urticaria, then Diphenhydramine
- If angioedema, bronchospasm, or hypotension, then Diphenhydramine, corticosteroids, and bronchodilators along with cessation of the NAC
- Restart NAC infusion at a slower rate 1 hour after administration of medical therapy
- Epinephrine is not recommended although it can be used in patients with severe progressive symptoms[7]
Common
- sulfur-smell causes nausea and vomiting. Consider mixing with juice or soda, in a cup with a lid and straw
Pharmacology
- Half-life:
- Metabolism:
- Excretion:
- Mechanism of Action:
- Intravenous acetylcysteine is indicated for the treatment of acetaminophen overdose by preventing depletion of glutathione reserves.
See Also
References
- ↑ Keays R, Harrison PM, Wendon JA, et al. Intravenous acetylcysteine in paracetamol-induced fulminant hepatic failure: a prospective controlled trial. BMJ. 1991;303(6809):1026-1029. (Prospective randomized controlled trial; 50 patients)
- ↑ Harrison PM, Keays R, Bray GP, et al. Improved outcome of paracetamol-induced fulminant hepatic failure by late administration of N-acetylcysteine. Lancet. 1990;335(8705):1572- 1573. (Retrospective analysis; 100 patients)
- ↑ Wasserman GS, Garg U. Intravenous administration of Nacetylcysteine: interference with coagulopathy testing. Ann Emerg Med. 2004;44(5):546-547. (Letter)
- ↑ Heard KJ. Acetylcysteine for acetaminophen poisoning. N Eng J Med. 2008;359(3):285-292. (Review)
- ↑ http://journals.lww.com/em-news/Fulltext/2012/02000/Toxicology_Rounds__Lessons_from_the_Courtroom_.9.aspx
- ↑ Sandilands EA, Bateman DN. Adverse reactions associated with acetylcysteine. Clin Toxicol (Phila). 2009;47(2):81-88. (Systematic literature review)
- ↑ Heard KJ. Acetylcysteine for acetaminophen poisoning. N Engl J Med. 2008; 359(3): 285-92.