N-Acetylcysteine (NAC) Infusion Protocol for Traumatic Liver Injury
The recommended N-acetylcysteine (NAC) infusion dose for traumatic liver injury is a loading dose of 150 mg/kg in 5% dextrose over 15 minutes, followed by a maintenance dose of 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours. 1
Rationale for NAC in Traumatic Liver Injury
- NAC serves as a hepatoprotective agent in traumatic liver injury by replenishing glutathione stores and providing antioxidant effects, similar to its mechanism in acetaminophen toxicity 1, 2
- NAC administration is recommended in any case of acute liver failure where hepatocyte damage is occurring or imminent, regardless of etiology 1
- NAC has been shown to decrease disease progression in hepatic failure, with studies demonstrating significant reductions in mortality, cerebral edema, and need for inotropic support 1
Administration Protocol
Intravenous Administration (Preferred in Trauma)
- Loading dose: 150 mg/kg in 5% dextrose over 15 minutes 1, 2
- Maintenance dose: 50 mg/kg over 4 hours, followed by 100 mg/kg over 16 hours 1, 2
- Continue administration until liver function tests normalize or clinical improvement is observed 1
Oral Administration (If IV access is limited)
- Loading dose: 140 mg/kg by mouth or nasogastric tube diluted to 5% solution 1
- Maintenance dose: 70 mg/kg by mouth every 4 hours for 17 doses 1
- Note: In trauma patients with active bleeding or altered mental status, oral administration may be precluded 1
Timing Considerations
- NAC should be administered as early as possible following traumatic liver injury 1, 3
- Maximum benefit is observed when NAC is initiated within 8 hours of injury, but it may still provide benefit when started up to 24 hours after injury 2, 3
- Caution: Initiation of NAC treatment >24 hours after hospital admission may potentially be harmful in critically ill patients 4
Monitoring During Treatment
- Monitor liver function tests (AST, ALT, alkaline phosphatase, total bilirubin) 1, 5
- Monitor coagulation parameters (INR, PT) 1, 5
- Monitor for adverse reactions, particularly allergic reactions which may include urticaria or bronchospasm 1
Management of Adverse Reactions
- For allergic reactions: discontinue infusion, administer antihistamines, and provide epinephrine for bronchospasm if needed 1
- Common adverse events include anaphylactic reactions with IV administration and gastrointestinal symptoms with oral administration 3
Special Considerations
- NAC has shown benefit in non-acetaminophen-induced acute liver failure, with one study demonstrating 96.4% transplant-free survival in patients receiving NAC compared to 23.3% in controls 6
- NAC (150 mg/kg) has demonstrated protective effects in ischemia-reperfusion liver injury models, which may be relevant in trauma settings 7
- NAC administration should be considered even in cases where the exact mechanism of liver injury is unclear, given its favorable risk-benefit profile 8
Pitfalls and Caveats
- Do not delay NAC administration while awaiting complete diagnostic workup in cases of severe traumatic liver injury 1
- Standard acetaminophen toxicity nomograms are not applicable to traumatic liver injury 5
- Be vigilant for signs of anaphylactic reactions, particularly during the loading dose administration 1, 3
- Consider potential drug interactions, particularly in polytrauma patients receiving multiple medications 5