NAC is NOT indicated for anticoagulant rodenticide poisoning
N-acetylcysteine (NAC) has no role in the treatment of anticoagulant rodenticide poisoning, as it is a specific antidote only for acetaminophen toxicity and does not address the mechanism of anticoagulant rodenticides. 1
Mechanism and Rationale
- NAC works exclusively by replenishing glutathione stores and preventing formation of the toxic acetaminophen metabolite NAPQI—mechanisms completely irrelevant to rodenticide poisoning 1, 2
- Anticoagulant rodenticides inhibit vitamin K₁-2,3-epoxide reductase, blocking synthesis of clotting factors II, VII, IX, and X—a pathway unaffected by NAC 3
- Administering NAC for rodenticide poisoning would be ineffective and potentially delay appropriate treatment 1
Correct Management of Anticoagulant Rodenticide Poisoning
Immediate Triage Decisions
- Refer immediately to emergency department if exposure involves suspected self-harm, abuse, misuse, or malicious administration regardless of dose 4
- Refer immediately if patient has any symptoms of anticoagulant toxicity (bleeding, bruising) regardless of dose 4
- Refer immediately for chronic ingestion to evaluate intent and potential coagulopathy 4
Risk Stratification by Dose
- Unintentional ingestion <1 mg active ingredient: Safe observation at home without laboratory monitoring (includes practically all unintentional pediatric ingestions) 4
- Unintentional ingestion ≥1 mg active ingredient: Evaluate for coagulopathy at 48-72 hours post-exposure 4
- Patients on therapeutic anticoagulants who ingest any dose should have baseline PT/INR and repeat at 48-72 hours 4
Definitive Treatment Protocol
For elevated INR without active bleeding:
- INR <4.0: No treatment required 3
- INR ≥4.0: Phytomenadione (vitamin K₁) 10 mg IV (100 mcg/kg for children) 3
For active bleeding:
- Prothrombin complex concentrate 50 units/kg (preferred—contains factors II, VII, IX, X) 3
- OR recombinant activated factor VII 1.2-4.8 mg 3
- OR fresh frozen plasma 15 mL/kg if concentrate unavailable 3
- PLUS phytomenadione 10 mg IV (100 mcg/kg for children) 3
Laboratory Monitoring
- Measure INR at 36-48 hours post-exposure for all cases except low-dose unintentional pediatric ingestions 3
- If INR normal at 48-72 hours, even with long-acting formulations, no further action required 3
- Outpatient facilities must obtain coagulation results within 24 hours 4
Critical Pitfalls to Avoid
- Do not administer vitamin K prophylactically before evaluation for coagulopathy 4
- Do not use ipecac or gastric lavage for decontamination 4
- Do not delay ED transport to administer activated charcoal 4
- Long-acting anticoagulant rodenticides (brodifacoum, bromadiolone, difenacoum) may cause anticoagulation for weeks to months after substantial ingestion due to high lipid solubility and enterohepatic circulation 3
Exception: Co-Ingestion Scenario
Only consider NAC if documented or suspected acetaminophen co-ingestion with rodenticide 1:
- Oral NAC: 140 mg/kg loading dose, then 70 mg/kg every 4 hours for 17 doses 1
- IV NAC: 150 mg/kg over 15 minutes, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours 1
Conflicting Research Evidence
While two retrospective studies 5, 6 suggested potential survival benefits of NAC in rodenticide poisoning, these findings contradict established pharmacological mechanisms and guideline recommendations. The proposed benefit lacks biological plausibility given NAC's specific mechanism of action in acetaminophen toxicity 1, 2. Contact your regional poison control center immediately for specific guidance on the particular rodenticide involved 1.