Toxin

Paraquat Poisoning

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Paraquat Poisoning, Paraquat, Paraquat Toxicity, Paraquat Lung

  • Epidemiology
  1. Responsible for 300,000 deaths per year in Asia-Pacific Region
  • Pathophysiology
  1. Dipyridilium compound
  2. Paraquat is an inexpensive herbicide typically used outside the U.S. (although some pockets of rural U.S. use)
    1. Paraquat is typically dyed blue to prevent Accidental Ingestion
  3. Poisoning typically occurs with intentional ingestion for Suicide
    1. Mortality 40-60% with ingestion of 15 ml (1 tbs, 0.5 oz) of 24% solution
    2. Results in multi-organ failure over the course of days
  4. Mechanism of systemic toxicity
    1. Cellular metabolism of Paraquat generates free radicals resulting in toxicity
    2. Inhibits NADP reduction to NADPH
    3. Mitochondrial toxicity
    4. Cell membrane dysfunction (lipid peroxidation)
  5. Pharmacokinetics
    1. Peak serum level at 4 hours after ingestion
    2. Excretion renal
  • Findings
  • Skin Contact (Corrosive) to Concentrated Paraquat Solutions
  1. Skin irritation
  2. Nail shedding
  3. Skin exposure rarely causes systemic effects
  • Findings
  • Systemic (Ingestion)
  1. Gastrointestinal
    1. Vomiting
    2. Mucosal inflammation and burns (local corrosive effects)
  2. Renal
    1. Acute Tubular Necrosis
  3. Hepatic
    1. Liver function abnormalities
  4. Neurologic
    1. Seizures
  5. Pulmonary Fibrosis (Paraquat Lung)
    1. Onset 5-31 days after ingestion
    2. Presents with Hypoxia
  • Labs
  1. Complete Blood Count
    1. High White Blood Cell Count is associated with poor prognosis
  2. Comprehensive Metabolic Panel
    1. Increased Serum Creatinine is associated with poor prognosis
  3. Plasma Paraquat Level
    1. Plasma Paraquat >2.64 mcg/ml at 3 hours is lethal in 100% of cases
  • Management
  1. Intravenous crystalloid
  2. Activated Charcoal within 4 hours of ingestion
  3. Avoid excessive Supplemental Oxygen
  4. Start Hemoperfusion within 6 hours of ingestion
  5. Disposition
    1. All symptomatic Paraquat exposures are admitted to hospital
    2. Observe all asymptomatic Paraquat exposures for at least 6 hours
  • References
  1. Tomaszewski (2021) Crit Dec Emerg Med 35(5): 28
  2. Gawarammana (2011) Br J Clin Pharmacol 72(5): 745-57 +PMID:21615775 [PubMed]