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