Paraquat: The Poison Potion

Abstract

Paraquat is a commonly used herbicide in India that has lethal consequences even on minimal consumption. The case fatality rate for this poisoning is high and there is dearth of evidence-based recommendation for the treatment of this poison. This review article explores the diagnosis and management of paraquat poisoning with an emphasis on recent advances in treatment. Though immunosuppressants and antioxidants are conventionally used, there is a gap in evidence to prove survival benefit of these treatment regimens. There are also some data showing the use of hemoperfusion (with toxin-specific cartridges) as an early intervention, i.e., within 4 hours of exposure to the poison. The recent drug, Edaravone, has also shown promise in the prevention of renal and hepatic injury in paraquat poisoning. Though it did not reduce pulmonary fibrosis in patients with paraquat poisoning, it delays the generation and development of pulmonary fibrosis. However, there is a need for more clinical and experimental studies to validate its use in paraquat poisoning.

Occult paraquat poisoning causing pneumomediastinum and organizing pneumonia

“…Haemoperfusion and haemofiltration have been advised in the early course of poisoning to reduce its concentration in the blood. 4 In conclusion, pneumomediastinum without the classical predisposing factors, in the background of GGOs, consolidation and/or interlobular thickening, is highly suggestive of paraquat lung in areas where this poisoning is prevalent. A detailed clinical history, careful examination of the oral cavity and recognition of organ failure triad of paraquat toxidrome are essential to make a timely diagnosis.…”

“…3 Severe systemic toxicity typically occurs following intentional or accidental oral ingestion, with mortality within 2-4 weeks in most cases. 4 The severe toxidrome after acute ingestion typically includes an organ failure triad of liver, kidney and lung, manifesting clinically as jaundice (conjugated hyperbilirubinaemia with elevated transaminases), acute kidney injury (requiring dialysis in many cases) and acute hypoxemic respiratory failure (typically requiring high-flow oxygen or mechanical ventilation), respectively. Because the history of toxin ingestion (suicidal or homicidal) may not be forthcoming in many cases, recognizing this organ failure triad remains paramount in daily emergency practice.…”

“…Haemoperfusion and haemofiltration have been advised in the early course of poisoning to reduce its concentration in the blood. 4…”

Pulmonary toxicity associated with occupational and environmental exposure to pesticides and herbicides

“…The use of this compound has been prohibited in the European Union. In other parts of the world, it is still a commonly used herbicide [12]. The Environmental Protection Agency in the USA classified paraquat as ‘restricted use’.…”

Paraquat poisoning

“…Although organophosphate accounts for the majority of the hospital admissions, poisoning by paraquat compounds is a major medical problem as it is associated with a very high mortality (case fatality rate of 50%-70%) and morbidity. 2 Paraquat is a toxic bipiridyl compound, and it is lethal even in very small amounts (15-20 mL of 20% w/v). The mode of poisoning is usually suicidal or accidental; and it should always be suspected in cases of corrosive oral and oesophageal ulcerations along with features of hepatic, renal or pulmonary involvement.…”