Emergency Medicine Book


Paraquat Poisoning

Aka: Paraquat Poisoning, Paraquat, Paraquat Toxicity, Paraquat Lung
  1. Epidemiology
    1. Responsible for 300,000 deaths per year in Asia-Pacific Region
  2. 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
  3. Findings: Skin Contact (Corrosive) to Concentrated Paraquat Solutions
    1. Skin irritation
    2. Nail shedding
    3. Skin exposure rarely causes systemic effects
  4. 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
  5. 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
  6. 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
  7. 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]

Paraquat (C0030493)

Definition (MSH) A poisonous dipyridilium compound used as contact herbicide. Contact with concentrated solutions causes irritation of the skin, cracking and shedding of the nails, and delayed healing of cuts and wounds.
Definition (CSP) poisonous dipyridilium compound used as a contact herbicide.
Concepts Hazardous or Poisonous Substance (T131) , Organic Chemical (T109)
MSH D010269
SnomedCT 22065005
LNC LP16830-9, MTHU009385
English Methyl Viologen, Paraquat, Viologen, Methyl, 4,4'-Bipyridinium, 1,1'-dimethyl-, Paraquat [Chemical/Ingredient], paraquat, Paraquat (substance)
Swedish Parakvat
Czech paraquat
Finnish Parakvatti
Japanese パラコート, メチルビオロゲン
Italian Metil viologeno, Paraquat
Polish Parakwat, Gramoxone
Spanish paraquat (sustancia), paraquat, Paraquat, Metil Viológeno
French Paraquat
German Methylviologen, Paraquat
Portuguese Metil Viologênio, Paraquat
Derived from the NIH UMLS (Unified Medical Language System)

Paraquat toxicity (C0413070)

Concepts Injury or Poisoning (T037)
SnomedCT 75017004
English Paraquat toxicity, Paraquat causing toxic effect, Paraquat toxicity (disorder)
Spanish intoxicación por paraquat (trastorno), intoxicación por paraquat, toxicidad del paraquat
Derived from the NIH UMLS (Unified Medical Language System)

Paraquat lung (C2931434)

Concepts Disease or Syndrome (T047)
MSH C537171
English Paraquat lung, Paraquat induced lung disease
Derived from the NIH UMLS (Unified Medical Language System)

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