What is the role of acetylcysteine (N-acetylcysteine) in treating parquet (presumably referring to paraquat) poisonings?

Acetylcysteine in Paraquat Poisoning

N-acetylcysteine (NAC) should be administered as part of an antioxidant therapy regimen in paraquat poisoning, as it may improve survival when combined with early digestive decontamination and hemodialysis. 1

Mechanism and Rationale

• Paraquat causes multi-organ damage through oxidative stress by generating reactive oxygen species that damage biomolecules 2
• NAC functions as an antioxidant that may help limit systemic toxicity in paraquat poisoning by counteracting oxidative damage 1
• While NAC is well-established for acetaminophen toxicity, its use in paraquat poisoning is based on its antioxidant properties rather than the specific mechanism used in acetaminophen overdose 3

Treatment Protocol

• Early administration of NAC is critical for maximum benefit, similar to its use in other forms of acute liver failure 4
• Continuous infusion of acetylcysteine (300 mg/kg/day for up to 3 weeks) has been reported in successful management of paraquat poisoning 1
• NAC should be used as part of a comprehensive treatment approach that includes:
  • Immediate gastrointestinal decontamination to prevent further absorption 2
  • Hemodialysis to enhance elimination of the toxin 2
  • Additional antioxidants such as deferoxamine (100 mg/kg in 24 hours) may be beneficial when combined with NAC 1

Evidence of Efficacy

• Case reports demonstrate survival in patients with potentially fatal paraquat poisoning when treated with NAC as part of an antioxidant regimen 1, 2
• In one reported case, a patient with multiple poor prognostic indicators survived after receiving early digestive decontamination, hemodialysis, and antioxidant therapy including NAC 1
• Alternative antioxidants such as S-carboxymethylcysteine have been used in settings where NAC is unavailable, with a reported mortality rate of 22.86% in a series of 35 patients 5

Important Considerations

• The timing of NAC administration appears critical - treatment should be initiated as early as possible after paraquat ingestion 2
• NAC is generally well-tolerated, with common adverse effects including nausea, vomiting, and gastrointestinal disturbances 4
• Less common side effects include skin rash (<5%) and transient bronchospasm (1-2%) 4
• NAC's safety profile is favorable compared to other antidotes - it is very well tolerated and available as a pharmaceutical preparation in a 20% sterile solution 3

Treatment Algorithm

1. Confirm paraquat poisoning through history and testing
2. Initiate immediate gastrointestinal decontamination 2
3. Start hemodialysis to enhance elimination 2
4. Begin antioxidant therapy:
   • NAC continuous infusion (300 mg/kg/day) 1
   • Consider additional antioxidants like deferoxamine and vitamin E 1, 2
5. Continue supportive care and monitor for multi-organ failure
6. Maintain NAC therapy for up to 3 weeks in severe cases 1

While the evidence for NAC in paraquat poisoning is not as robust as for acetaminophen toxicity, case reports suggest that early administration as part of a comprehensive treatment approach may improve outcomes in this otherwise highly lethal poisoning.