N-acetylcysteine (NAC) Injection Administration Site
For N-acetylcysteine (NAC) injections, the recommended administration site is intravenous (IV) through a peripheral or central venous line, not an intramuscular or subcutaneous injection site. 1
Administration Routes for NAC
- NAC is administered intravenously in cases of acetaminophen overdose or suspected hepatotoxicity 1
- The IV route is preferred when oral administration is precluded (e.g., by gastrointestinal bleeding or worsening mental status) 1
- NAC is not administered as an intramuscular or subcutaneous injection 1
IV NAC Administration Protocol
Standard Intravenous Dosing:
- Loading dose: 150 mg/kg in 5% dextrose over 15 minutes 1
- Maintenance dose: 50 mg/kg given over 4 hours followed by 100 mg/kg administered over 16 hours 1
Alternative Simplified Protocol:
- Preparation: IV-NAC 30 g in 1 L of 5% dextrose in water 2
- Loading dose: 150 mg/kg administered over 1 hour 2
- Maintenance: 14 mg/kg/h for 20 hours 2
Important Considerations for Administration
- Monitor for allergic reactions during administration, especially during the loading dose 1
- Allergic reactions may present as transient, patchy skin erythema or mild urticaria 3
- If allergic reactions occur, they can be managed with discontinuation, antihistamines, and epinephrine for bronchospasm 1
- Be cautious about the preparation of NAC solution to avoid excess free water administration which can lead to hyponatremia 4
Timing of NAC Administration
- NAC should be given as early as possible after acetaminophen overdose 1
- The incidence of severe hepatotoxicity is 2.9% when NAC treatment delay is less than 8 hours and increases to 26.4% when treatment delay exceeds 10 hours 1
- NAC may still provide benefit even when administered 48 hours or more after ingestion 1
Clinical Indications for NAC
- Administer NAC to patients with hepatic failure thought to be due to acetaminophen 1
- Begin NAC promptly in all patients where acetaminophen levels, quantity ingested, or rising aminotransferases indicate impending or evolving liver injury 1
- NAC may be used in cases of acute liver failure where acetaminophen ingestion is possible or when knowledge of circumstances surrounding admission is inadequate 1
Potential Complications to Monitor
- Watch for hyponatremia, especially in pediatric patients receiving NAC in D5W 4
- Monitor for anaphylactoid reactions, which are more common during the loading dose 1, 3
- For massive acetaminophen overdose (above the "300-line" on the nomogram), higher NAC doses may be necessary 5
Remember that proper IV administration of NAC is critical for effective treatment of acetaminophen toxicity and prevention of hepatic failure.