NAC Infusion for Yellow Phosphorus Rodenticide Poisoning
N-acetylcysteine (NAC) should be administered to patients with acute liver failure from yellow phosphorus rodenticide poisoning, as it significantly improves survival and reduces mortality despite the absence of specific antidote for this toxin. 1, 2, 3
Evidence for NAC in Rodenticide-Induced Acute Liver Failure
Survival Benefits
NAC treatment demonstrates significant survival benefits in rodenticide poisoning, with pooled analysis of randomized controlled trials showing improved recovery rates (OR: 3.97; 95% CI: 1.69-9.30) and reduced mortality (OR: 0.25; 95% CI: 0.11-0.59). 3
Retrospective studies confirm this mortality reduction (OR: 0.34; 95% CI: 0.15-0.78), with real-world data from Indian tertiary care settings showing significantly higher survival rates in NAC-treated versus non-NAC groups (p ≤ 0.03). 2, 3
Case series report successful recovery in 2 out of 3 patients with rodenticide-induced acute liver failure treated with NAC, including one pregnant patient. 1
Mechanism and Rationale
NAC functions as a glutathione precursor and provides antioxidant effects that protect hepatocytes from oxidative damage caused by yellow phosphorus, similar to its mechanism in acetaminophen toxicity. 4, 5
The American Gastroenterological Association recommends NAC for acute liver failure regardless of etiology, with meta-analysis showing improvements in overall survival (76% vs 59%) and liver transplant-free survival (64% vs 26%) in non-acetaminophen related acute liver failure. 6, 4, 5
Treatment Protocol
Timing and Administration
Initiate NAC as early as possible after yellow phosphorus ingestion, as time lag ≥24 hours is a significant risk factor for mortality (RR: 3.479; 95% CI: 1.137-10.645). 2
NAC is most beneficial when started early in the disease course, particularly in patients with grades I-II hepatic encephalopathy. 4, 5
Dosing Considerations
Mean oral loading dose reported in rodenticide poisoning studies: 7580.95 ± 2204.29 mg, with maintenance dose of 3694.53 ± 2322.58 mg. 2
Standard intravenous NAC protocols for acute liver failure should be followed, with treatment duration extended based on clinical response and liver function parameters. 4, 5
Safety Profile
NAC demonstrates excellent safety, with 93.4% of patients experiencing no adverse effects in rodenticide poisoning studies. 2
Common side effects include nausea, vomiting, skin rash (<5%), and transient bronchospasm (1-2%). 4, 5
Critical Management Points
Risk Stratification
Yellow phosphorus poisoning itself is a significant risk factor for mortality (RR: 2.888; 95% CI: 1.179-7.079), requiring aggressive early intervention. 2
Monitor for development of acute liver failure with serial liver function tests, coagulation studies (PT/INR), and hepatic encephalopathy grading. 7
Adjunctive Measures
Contact liver transplantation center immediately for all patients with severe yellow phosphorus poisoning and PT <50%, as transplantation remains the definitive treatment for severe intoxication. 7, 1, 8
Consider therapeutic plasma exchange (plasmapheresis) in severe cases, as it may remove the toxin, metabolites, and inflammatory mediators. 8
Maintain serum sodium 140-145 mmol/L, monitor glucose every 2 hours minimum, and provide multiorganic support as needed. 7
Monitoring Parameters
Serial assessment of hepatic encephalopathy grade (determines prognosis and NAC benefit). 5, 7
Apply King's College criteria or lactate levels for transplant evaluation: pH <7.3 after adequate volume resuscitation, or lactate >3.5 mmol/L at 4 hours or >3.0 mmol/L at 12 hours. 7
Track INR trends between days 3-4: rising INR associates with only 7% survival versus 79% if INR decreases. 7
Clinical Pitfalls to Avoid
Do not delay NAC administration while awaiting definitive diagnosis or transplant evaluation, as early treatment is critical for survival. 4, 2
Do not discontinue NAC prematurely; continue treatment for extended duration (potentially 3+ days) based on clinical response and liver function improvement. 2, 9
Recognize that yellow phosphorus poisoning has no specific antidote—NAC provides supportive hepatoprotection while awaiting potential transplantation or spontaneous recovery. 1, 8