The toxicokinetics of acute paraquat poisoning in specific patients: a case series

Paraquat is a non-selective contact herbicide that is absorbed through the digestive tract and skin and can cause multiple organ damage. The toxicokinetics of paraquat poisoning in specific patients are rarely reported. Case 1 was a 76-year-old man who intermittently immersed his perineum in diluted paraquat solution for 3 consecutive days because of eczema of the perineal skin. On admission, the patient’s scrotal skin was severely corroded and his blood paraquat concentration was 0.5 μg/mL. He developed severe kidney and lung damage after admission and died on Day 6 of admission. Case 2 was a 23-year-old woman who ingested paraquat during gestational week 36. Her initial blood paraquat concentration was 0.81 μg/mL. The patient refused hemoperfusion and a cesarean section. She birthed a baby girl 83 hours after ingesting paraquat. Paraquat concentrations in postnatal maternal blood, fetal blood, umbilical cord blood, and amniotic fluid were 0.19 μg/mL, 0.23 μg/mL, 0.20 μg/mL, and 0.47 μg/mL, respectively. The baby died within hours of birth and the mother died of refractory respiratory failure 2 days after delivery. This paper provides clues about paraquat toxicokinetics in specific patient types and indicates that paraquat can be absorbed through the scrotal skin and the placental barrier.

Fetal outcomes after intentional ingestion of paraquat: A case report

RATIONALE

Despite the fact that treatment of paraquat poisoning in pregnant women and their fetuses is challenging and raises ethical issues, it is rarely reported in the literature. We report the case of a pregnant woman who took paraquat intentionally.

PATIENT CONCERNS

A 36-year-old woman at 38 weeks gestational age, in an apparent suicide attempt, drank 1 mouthful (about 20 ml) of paraquat solution. Ten hours later, her urine dithionate test showed light blue color with a plasma paraquat concentration of 0.547 μg/ml. Six hours after admission, a male infant, whose plasma paraquat concentration was 0.761 μg/ml, together with 0.673 μg/ml in the amniotic fluid measured by high-performance liquid chromatography, was delivered but the woman's lung, liver, and kidney function declined rapidly.

DIAGNOSIS

INTERVENTIONS:: Because of placenta previa and multiple organ failure, emergency cesarean section, and panhysterectomy were performed for the pregnant woman. Intravenous injection of antibiotic to prevent infection and dexamethasone 30 mg once a day were administered. Mechanical ventilation was performed for the infant and meropenem and penicillin injection was administered.

OUTCOMES

The infant died 33 hours after birth while the mother died on the 3rd day after ingestion.

LESSONS

Paraquat can enter the fetus through the placenta and the amniotic fluid via fluid exchange. The pathological changes of fetal organs may relate to gestational age, and the prognosis was very poor in both the mother and the fetus.

Clinical outcome of paraquat poisoning during pregnancy

Objectives: We aimed to describe clinical characteristics and outcomes of paraquat poisoning in pregnant patients, their fetuses, and newborns. Methods: We performed a retrospective study of pregnant patients who were exposed to paraquat, from the Ramathibodi Poison Center Toxic Exposure Surveillance System, during a 5-year period. Results: Thirty-six patients, representing every trimester, were included. All experienced oral exposure with a mean age of 22.7 years and mean gestational age (GA) of 23.1 weeks. Most had gastrointestinal symptoms and signs. Systemic effects, which mainly comprised of acute kidney injury (AKI), were found in 13 patients (36.1%); obstetric complications were noted in five patients (13.9%). Medical treatment included intravenous dexamethasone and cyclophosphamide. Some patients received hemodialysis and endotracheal intubation. Nine patients delivered during hospitalization; four newborns (maternal GAs of 30-36 weeks with systemic effects) died after delivery. One patient with GA 26 weeks delivered and died, but her newborn survived. Mortality rates of pregnant patients and their offspring delivered in-hospital were 25% and 44.4%, respectively; all deaths occurred in patients with systemic toxicity. The median length of hospital stay was 6 days. Notably, AKI, hepatotoxicity, and maximum white blood cell count significantly differed between dead and surviving patients. We followed-up 15 surviving patients who were discharged before delivery to assess delivery outcomes. All 15 patients and newborns survived without reports of congenital anomalies. Conclusions: Paraquat poisoning during pregnancy caused high fatalities in pregnant patients, fetuses, and newborns who were delivered during hospitalization, especially among patients with systemic effects. The GA of the pregnancy affected fetal outcomes, both in utero and at birth. Selective, appropriate management is warranted and might be guided by poisoning severity and the GA of the pregnancy.

Paraquat Exposure of Pregnant Women and Neonates in Agricultural Areas in Thailand

This study aimed to assess paraquat concentrations in the urine of women at 28 weeks of pregnancy, delivery and 2 months postpartum and in the meconium of neonates. In all, 79 pregnant women were recruited from three hospitals located in agricultural areas in Thailand. The subjects were interviewed about personal characteristics, agricultural activities and pesticide use patterns. Paraquat was analyzed in urine and meconium using high performance liquid chromatography equipped with a fluorescence detector. The geometric mean (GSD) of urinary paraquat concentrations at 28 weeks of pregnancy, delivery and 2 months postpartum were 2.04 (4.22), 2.06 (5.04) and 2.42 (5.33) ng/mL, respectively. The urinary paraquat concentrations at 28 weeks of pregnancy, delivery and 2 months postpartum between agriculturist and non-agriculturist were not significantly different (p = 0.632, p = 0.915, p = 0.57, respectively). The geometric mean (GSD) of paraquat concentration in the meconium was 33.31 (4.59) ng/g. The factors predicting paraquat exposures among pregnant women and neonates included working outside, living near farmland, having family members who work on a farm, drinking well water and using herbicides or paraquat.

Paraquat poisonings: mechanisms of lung toxicity, clinical features, and treatment

Paraquat dichloride (methyl viologen; PQ) is an effective and widely used herbicide that has a proven safety record when appropriately applied to eliminate weeds. However, over the last decades, there have been numerous fatalities, mainly caused by accidental or voluntary ingestion. PQ poisoning is an extremely frustrating condition to manage clinically, due to the elevated morbidity and mortality observed so far and due to the lack of effective treatments to be used in humans. PQ mainly accumulates in the lung (pulmonary concentrations can be 6 to 10 times higher than those in the plasma), where it is retained even when blood levels start to decrease. The pulmonary effects can be explained by the participation of the polyamine transport system abundantly expressed in the membrane of alveolar cells type I, II, and Clara cells. Further downstream at the toxicodynamic level, the main molecular mechanism of PQ toxicity is based on redox cycling and intracellular oxidative stress generation. With this review we aimed to collect and describe the most pertinent and significant findings published in established scientific publications since the discovery of PQ, focusing on the most recent developments related to PQ lung toxicity and their relevance to the treatment of human poisonings. Considerable space is also dedicated to techniques for prognosis prediction, since these could allow development of rigorous clinical protocols that may produce comparable data for the evaluation of proposed therapies.