Acute diquat poisoning resulting in toxic encephalopathy: a report of three cases

A ratiometric fluorescence method for the detection of diquat by a large Stokes shift fluorescent probe

Pesticide residues are currently a prominent concern for food safety, and the development of a rapid, convenient, and accurate method for detecting pesticide residues is crucial to ensure the quality of agricultural products. In this study, a small molecule fluorescent probe based on biphenyl disulfonic acid (BDSA) was designed and prepared, and a sensitive, specific, and rapid detection method for diquat (DQ) and paraquat (PQ) was developed. The fluorescent molecule (BDSA-NDA) was synthesized through amide reaction between BDSA and 1,8-naphthalic anhydride, which exhibited cyan fluorescence (480 nm) when excited at 305 nm in aqueous solution with a large Stokes shift (>150 nm). Diquat and paraquat were found to quench the fluorescence of the probe through internal filtration effect (IFE) and photoelectron transfer (PET). Moreover, diquat possessed a large conjugated structure that emitted fluorescence at 340 nm which was assembled into a pair of ratio fluorescence with BDSA-NDA. Under optimized experimental conditions, the developed method achieved detection limits of 0.003 mg/L for diquat and 0.202 mg/L for paraquat. Furthermore, it could identify paraquat doped in diquat formulations. Additionally, when applied to environmental water samples as well as rice and urine, this detection method demonstrated good recovery rates (water: 96.2-100.6 %, rice: 93.5-101.9 %, urine: 96-103.7 %), meeting actual sample detection requirements effectively. This work presents a novel approach for rapidly detecting diquat and paraquat residues which holds practical application value in areas such as pesticide residue analysis in foods, environmental or clinical samples.

Imaging Findings and Toxicological Mechanisms of Nervous System Injury Caused by Diquat

Diquat (DQ) is a nonselective bipyridine herbicide with a structure resembling paraquat (PQ). In recent years, the utilization of DQ as a substitute for PQ has grown, leading to an increase in DQ poisoning cases. While the toxicity mechanism of DQ remains unclear, it is primarily attributed to the intracellular generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) through the process of reduction oxidation. This results in oxidative stress, leading to a cascade of clinical symptoms. Notably, recent reports on DQ poisoning have highlighted a concerning trend: an upsurge in cases involving neurological damage caused by DQ poisoning. These patients often present with severe illness and a high mortality rate, with no effective treatment available thus far. Imaging findings from these cases have shown that neurological damage tends to concentrate on the brainstem. However, the specific mechanisms behind this poisoning remain unclear, and no specific antidote exists. This review summarizes the research progress on DQ poisoning and explores potential mechanisms. By shedding light on the nerve damage associated with DQ poisoning, we hope to raise awareness, propose new avenues for investigating the mechanisms of DQ poisoning, and lay the groundwork for the development of treatment strategies for DQ poisoning. Trial registration number: 2024PS174K.

Association between toxicity-index of diquat and in-hospital mortality in patients with acute diquat poisoning: a retrospective cohort study

BACKGROUND

This study investigates the impact of diquat toxicity levels on in-hospital mortality rates among patients with acute diquat poisoning. It aims to clarify the relationship between diquat toxicity scores and the likelihood of death during hospitalization.

METHODS

A retrospective cohort study was conducted on 98 individuals with acute diquat poisoning. Data on post-ingestion time, initial diquat plasma concentration, and clinical outcomes were systematically collected for all participants. The toxicity-index of diquat was calculated based on post-ingestion time and initial diquat plasma concentration. Logistic regression analysis was utilized to assess the association between the toxicity-index of diquat and in-hospital mortality rates, adjusting for potential confounding variables such as age, comorbidities, and treatment interventions.

RESULTS

The study found that the overall prevalence of in-hospital mortality was 34.7%, with 58.2% in males. The multivariable-adjusted regression coefficient for in-hospital mortality associated with the toxicity-index was 1.09, with a 95% confidence interval (CI) of 1.01-1.17. Subsequent exploratory subgroup analysis indicated that there were no significant interactions (all p values for interaction were >0.05).

CONCLUSIONS

The study found that higher diquat toxicity-index values correlate with increased in-hospital mortality in acute diquat poisoning cases, indicating that the toxicity-index could be a useful biomarker for assessing mortality risk.

Images in acute diquat poisoning, including hepatic portal venous gas and gastrointestinal pneumatosis on computed tomography

INTRODUCTION

Severe diquat poisoning often leads to acute kidney injury, gastrointestinal injury, paralytic ileus, rhabdomyolysis, respiratory failure, refractory circulatory failure, and brainstem damage.

CASE SUMMARY

A previously healthy 38-year-old man was admitted to our hospital with anuria, mild abdominal distension, and calf pain after ingesting diquat (200 g/L) 100 mL approximately 13 h before presentation. His blood diquat concentration was 8.14 µg/L on admission. Gastrointestinal catharsis, haemoperfusion, and haemodiafiltration were performed. Subsequently, he developed marked abdominal distention, impaired consciousness, hypotension, and respiratory failure, leading to death.

IMAGES

Computed tomography revealed gas accumulation in the portal venous system and mesenteric vessels. Moreover, gastrointestinal pneumatosis was present. Computed tomography also revealed changes in the lung, brainstem, and calf muscles.

CONCLUSION

Diquat poisoning can result in acute kidney injury, hepatic injury, gastrointestinal injury, paralytic ileus, rhabdomyolysis, refractory circulatory failure, brainstem damage, and hepatic portal venous gas, all observed in this patient.

Microhemorrhages in diquat-induced encephalopathy identified using susceptibility-weighted imaging

INTRODUCTION

Intracerebral bleeding that predominantly affects the pons, midbrain, cerebral peduncle, basal ganglia, and thalamus may occur in severe diquat poisoning. We employed magnetic resonance-susceptibility-weighted imaging to highlight the presence of microhemorrhages in a patient with diquat poisoning.Case summary: A 15-year-old female patient presented with kidney and liver damage after ingesting diquat. Three days later, she developed coma. She received seven sessions of hemoperfusion and was discharged with residual cognitive impairment and right limb muscle weakness after 66 days of hospitalization.Images: Cranial computed tomography on day 5 and magnetic resonance imaging on day 8 revealed swelling in the pons, midbrain, and thalamus without evidence of hemorrhage. However, susceptibility-weighted imaging on day 8 demonstrated multiple punctate low signals, suggesting the presence of microhemorrhages.

CONCLUSION

Susceptibility-weighted imaging is a useful technique for detecting microhemorrhages in patients with diquat-induced encephalopathy, as microhemorrhages are often not detectable on computed tomography or conventional magnetic resonance imaging.

Investigating layer-by-layer films of carbon nanotubes and nickel phthalocyanine towards diquat detection

The indiscriminate use of pesticides makes us susceptible to the toxicity of these chemical compounds, which may be present in high quantities in our food. It is crucial to develop inexpensive and rapid methods for determining these pesticides for government control or even for the general population. In this study, we investigated the fabrication of self-assembled LbL films using multi-walled carbon nanotubes (MWCNT) and nickel tetrasulphonated phthalocyanine (NiTsPc) as an electrochemical sensor for the herbicide Diquat (DQ). The Layer-by-Layer (LbL) assembly of the (MWCNT/NiTsPc) film was examined, along with its structural and morphological characteristics. The effect of the number of layers in DQ detection was evaluated by cyclic voltammetry, followed by the detection through differential pulse voltammetry. The achieved limit of detection was 9.62 × 10-7 mol L-1. A ~ 30% decrease in sensitivity was observed in the presence of Paraquat, a banned herbicide and electrochemical interferent due to the structural similarities, which is regularly neglected in the most published studies. The sensor was tested in real samples, demonstrating a recovery of 98.5% in organic apples.

Interpretable machine learning for the prediction of death risk in patients with acute diquat poisoning

The aim of this study was to develop and validate predictive models for assessing the risk of death in patients with acute diquat (DQ) poisoning using innovative machine learning techniques. Additionally, predictive models were evaluated through the application of SHapley Additive ExPlanations (SHAP). A total of 201 consecutive patients from the emergency departments of the First Hospital and Shengjing Hospital of China Medical University admitted for deliberate oral intake of DQ from February 2018 to August 2023 were analysed. The initial clinical data of the patients with acute DQ poisoning were collected. Machine learning methods such as logistic regression, random forest, support vector machine (SVM), and gradient boosting were applied to build the prediction models. The whole sample was split into a training set and a test set at a ratio of 8:2. The performances of these models were assessed in terms of discrimination, calibration, and clinical decision curve analysis (DCA). We also used the SHAP interpretation tool to provide an intuitive explanation of the risk of death in patients with DQ poisoning. Logistic regression, random forest, SVM, and gradient boosting models were established, and the areas under the receiver operating characteristic curves (AUCs) were 0.91, 0.98, 0.96 and 0.94, respectively. The net benefits were similar across all four models. The four machine learning models can be reliable tools for predicting death risk in patients with acute DQ poisoning. Their combination with SHAP provides explanations for individualized risk prediction, increasing the model transparency.

Two cases of diquat poisoning in adolescent children

Diquat (DQ) is among the most widely used herbicides, and its intake can cause severe systemic toxicity that manifests rapidly. The resultant symptoms can cause the dysfunction of a range of tissues and organs,. As there is no specific antidote for diquat poisoning and the efficacy of extant treatments is suboptimal, physicians must acquire a more comprehensive understanding of the most effective approaches to managing affected patients. Relative few studies have been published to date focused on diquat poisoning in pediatric patients. In this report, we compare two similar cases of juvenile diquat poisoning with dynamic changes in clinical manifestations, laboratory values, and imaging results. For the first time, the difference in whether to perform blood flow perfusion and the time difference of initiation of hemoperfusion had a clear clinical difference in the subsequent effects of diquat poisoning in children with diquat poisoning. Limited evidence is available regarding the efficacy of early hemoperfusion for diquat poisoning; however, the differences in clinical outcomes articulated here highlight the benefits of early and timely hemoperfusion therapy in the treatment of DQ toxicity in children, in conjunction with primary supportive care in the management of DQ poisoning in children.

Prognosis prediction of procalcitonin within 24 h for acute diquat poisoning

BACKGROUND

To explore the predictive value of procalcitonin (PCT) within 24 h after poisoning for prognosis of acute diquat poisoning.

METHODS

This retrospective study included acute diquat poisoning patients in the Nanyang City Hospital between May 2017 and July 2021.

RESULTS

Among the 45 patients included, 27 survived. The maximum PCT value within 24 h after poisoning was significantly higher in the non-survival patients [9.65 (2.63, 22.77) vs. 0.15 (0.10, 0.50) µg/mL, P < 0.001] compared to the survival patients. The area under the ROC curve (AUC) indicated that the maximum PCT value within 24 h had a good predictive value (AUC = 0.905, 95% CI: 0.808-1.000) compared to ingested quantity (AUC = 0.879, 95% CI: 0.776-0.981), serum creatinine (AUC = 0.776, 95% CI: 0.640-0.912), or APACHE II score (AUC = 0.778, 95% CI: 0.631-0.925). The predictive value of maximum PCT value within 24 h was comparable with blood lactate (AUC = 0.904, 95%CI: 0.807-1.000).

CONCLUSIONS

The maximum PCT value within 24 h after poisoning might be a good predictor for the prognosis of patients with acute diquat poisoning.

Simultaneous determination of diquat, paraquat, glufosinate, and glyphosate in plasma by liquid chromatography/tandem mass spectrometry: from method development to clinical application

Diquat (DQ), paraquat (PQ), glufosinate (GLU), and glyphosate (GLYP) are commonly used herbicides that have been confirmed to be toxic to humans. Rapid and accurate measurements of these toxicants in clinical practice are beneficial for the correct diagnosis and timely treatment of herbicide-poisoned patients. The present study aimed to establish an efficient, convenient, and reliable method to achieve the simultaneous quantification of DQ, PQ, GLU, and GLYP in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS) without using derivatization or ion-pairing reagents. DQ, PQ, GLU, and GLYP were extracted by the rapid protein precipitation and liquid-liquid extraction method and then separated and detected by LC-MS/MS. Subsequently, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, extraction recovery, matrix effect, dilution integrity, and stability were evaluated to validate the method based on the FDA criteria. Finally, the validated method was applied to real plasma samples collected from 166 Chinese patients with herbicide poisoning. The results showed satisfactory linearity with low LOD (1 ng/mL for DQ and PQ, 5 ng/mL for GLU, and 10 ng/mL for GLYP, respectively) and low LOQ (5 ng/mL for DQ and PQ, 25 ng/mL for GLU and GLYP, respectively). In addition, the precision, accuracy, extraction recovery, and stability of the method were acceptable. The matrix effect was not observed in the analyzed samples. Moreover, the developed method was successfully applied to determine the target compounds in real plasma samples. These data provided reliable evidence for the application of this LC-MS/MS method for clinical poisoning detection.

Melatonin increased antioxidant capacity to ameliorate growth retardation and intestinal epithelial barrier dysfunction in diquat-challenged piglets

BACKGROUND

Diquat is a common environmental pollutant, which can cause oxidative stress in humans and animals. Diquat exposure causes growth retardation and intestinal damage. Therefore, this study was performed to investigate the effects of melatonin on diquat-challenged piglets.

RESULTS

Dietary supplementation with 2 mg kg-1 melatonin significantly increased the average daily gain and feed conversion rate in piglets. Melatonin increased antioxidant capacity, and improved intestinal epithelial barrier function of duodenum and jejunum in piglets. Moreover, melatonin was found to regulated the expression of immune and antioxidant-related genes. Melatonin also alleviated diquat-induced growth retardation and anorexia in diquat-challenged piglets. It also increased antioxidant capacity, and ameliorated diquat-induced intestinal epithelial barrier injury. Melatonin also regulated the expression of MnSOD and immuner-elated genes in intestinal.

CONCLUSION

Dietary supplementation with 2 mg kg-1 melatonin increased antioxidant capacity to ameliorate diquat-induced oxidative stress, alleviate intestinal epithelial barrier injury, and increase growth performance in weaned piglets. © 2023 Society of Chemical Industry.

Elucidating the mechanisms underlying astrocyte-microglia crosstalk in hippocampal neuroinflammation induced by acute diquat exposure

The transition from paraquat (PQ) to diquat (DQ), both organic dication herbicides, in China has led to significant increases in the number of acute DQ poisoning cases. Case studies have shown that acute DQ poisoning resulted in injury to the central nervous system (CNS), but the mechanism underlying the injury remains to be explored. The present study aimed to investigate how DQ influenced purinergic signaling between astrocytes and microglia and whether extracellular ATP (eATP) was involved in promoting neuroinflammation induced by acute DQ toxicity through the activation of the P2X4/NLRP3 signaling pathway. We constructed a rat model of acute DQ toxicity to observe the pathological changes in hippocampal tissues after DQ exposure and measure the expression levels of IL-1β and TNF-α in the hippocampal tissue. We also established an in vitro co-culture model of C6 astrocytes and BV-2 microglia using transwell chambers, measured the amount of eATP secreted into C6 astrocytes after DQ treatment, and assessed the inflammatory response and changes in the P2X4/NLRP3 signaling pathway in BV-2 microglia. The results showed that the neurons in the hippocampal tissue of rats exhibited loose arrangement, nuclear consolidation, and necrosis after DQ exposure, and IL-1β and TNF-α levels were signification higher in the hippocampal tissue after DQ exposure. DQ exposure to the co-cultured cells induced an increase in ATP secretion from C6 astrocytes as well as a significant increase of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. In contrast, pretreatment of C6 astrocytes with apyrase (an ATP hydrolase) resulted in a significant decrease of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. Furthermore, inhibition of P2X4 expression in BV-2 microglia by transfection with si-P2X4 effectively reversed the increase of NLRP3, IL-1β, and IL-18 in BV-2 microglia induced by DQ when co-cultured with C6 astrocytes. These results indicate that astrocytes can activate the P2X4/NLRP3 signaling pathway in microglia through the DQ-induced extracellular release of ATP to promote neuroinflammation in rat hippocampal tissue.

Non-cytochrome P450 enzyme aldehyde oxidase is involved in the oxidative metabolic pathway of diquat and its detoxification effect

Diquat (DQ) poisoning has garnered attention in recent years, primarily due to the rising incidence of cases worldwide, coupled with the absence of a viable antidote for its treatment. Despite the fact that diquat monopyridone (DQ-M) has been identified as a significant metabolite of DQ, the enzyme responsible for its formation remains unknown. In this study, we have identified aldehyde oxidase (AOX) as a vital enzyme involved in DQ oxidative metabolism. The metabolism of DQ to DQ-M was significantly inhibited by AOX inhibitors including raloxifene and hydralazine. The source of oxygen incorporated into DQ-M was proved to be from water through a H218O incubation experiment which further corroborated DQ-M formation via AOX metabolism. The product of DQ-M in vitro generated by fresh rat tissues co-incubation was consistent with its AOX expression. The result of the molecular docking analysis of DQ and AOX protein showed that DQ is capable of binding to AOX. Furthermore, the cytotoxicity of DQ was significantly higher than DQ-M at the same concentration tested in six cell types. This work is the first to uncover the involvement of aldehyde oxidase, a non-cytochrome P450 enzyme, in the oxidative metabolic pathway of diquat, thus providing a potential target for the development of detoxification treatment.

Mid-to-late stage diquat accumulation in the central nervous system: A severe case of oral poisoning

A 54-year-old woman in good health was admitted to our hospital with diquat poisoning. The patient drank an unknown dose of diquat, and acute kidney injury developed early. However, there were no obvious pulmonary abnormalities and no signs of central nervous system toxicity in the early stage. The woman underwent active treatment, which resulted in a significant decrease in blood diquat levels, but her lung condition progressively worsened and neurological symptoms developed. Fortunately, the patient survived after intensive hemoperfusion combined with continuous renal replacement therapy (CRRT), intracranial pressure reduction, and anti-infective treatment. This case report highlights the importance of being aware of the development of delayed pulmonary symptoms and neurologic complications when caring for patients poisoned with diquat, even in those with low diquat blood concentrations. Interestingly, we also detected the concentration of diquat in the cerebrospinal fluid (CSF) of patients with diquat poisoning, and found that the rate of decrease of diquat concentration in the CSF was considerably slower than that in the blood.Notably, a specific correlation was observed between the concentration of diquat in the CSF, rather than in the blood, and both the intracranial pressure (ICP) and the severity of cerebral edema in this patient.

Dienediamine: A safe surrogate for the herbicide paraquat

Paraquat (PQ) has been used as an herbicide worldwide because of its potent activity against weeds. However, it is highly toxic to humans. The very high fatality of PQ poisoning is due to its inherent toxicity and the lack of any effective treatment. Consequently, developing a non-toxic herbicide with comparable efficacy to PQ will contribute to global food security and help prevent PQ-related fatalities. Herein, we report a new herbicide called dienediamine, which was discovered from how to intervene the redox cycle of PQ, an inherent toxicity nature. Dienediamine, the "reduced" form of PQ with no function as an electron transfer agent, was shown to be non-toxic through comprehensive in vivo and in vitro experiments at molar concentrations equivalent to PQ's absolute lethal dose. Remarkably, dienediamine can undergo conversion to PQ under natural sunlight and ambient air conditions, exhibiting herbicidal activities that are comparable to those of PQ. The conversion of dienediamine to PQ, which is toxic to chloroplasts, is the key mechanism underlying its potent herbicidal activity. Our study discovers that dienediamine is a safe and superior alternative to PQ, possessing significant potential for application in sustainable agriculture globally.

Acute diquat poisoning case with multiorgan failure and a literature review: A case report

BACKGROUND

With the withdrawal of paraquat from the market, diquat is widely used, so the treatment of diquat poisoning has become one of the focuses of emergency poisoning diagnosis and treatment.

CASE SUMMARY

We studied the case of a 17-year-old male patient who drank 200 mL (20 g/100 mL) of diquat solution two hours before arriving at the hospital. Despite the use of treatments such as gastric lavage, hemoperfusion, continuous hemodialysis, glucocorticoids, and organ support, the patient's condition rapidly progressed to multiorgan failure, and he died 23.5 h after admission.

CONCLUSION

We summarized the clinical characteristics and treatment strategies of diquat poisoning through this case and performed a literature review to provide a basis and direction for clinical treatment.

Surface-enhanced Raman scattering of a gold core-silver shell-sponge substrate for detection of thiram and diquat

Aiming at the difficulty of traditional pesticide sampling, a low-cost and convenient flexible surface enhanced Raman scattering (SERS) gold core-silver shell-sponge (Au-Ag-sponge) substrate was synthesized by chemical reduction. The SERS substrate consisted of Au-AgNPs and a melamine sponge. The sponge had a rich open pore structure, which could well "capture" Au-AgNPs, generating a large number of "hot spots". The SERS enhancement activity of the flexible substrate was characterized with rhodamine 6G (R6G) Raman probe molecules. The substrate showed good activity to 10-12 M rhodamine 6G with an enhancement factor (EF) of 7.72 × 106. Applying this substrate to the qualitative and quantitative detection of pesticide residues, the results showed that the Raman intensity was well related to the concentration of pesticide solution with the range of 0.1-10 mg L-1 of thiram and 1-10 mg L-1 of diquat. Furthermore, the substrate was analyzed by finite difference time domain (FDTD) simulation and the results were in good agreement with the experimental results. The reason for the difference in Raman signals of pesticide molecules on the same substrate was the different binding modes of Au-AgNPs on the sponge. Finally, we pointed out the advantages of flexible substrates in the field of pesticide residues, as well as future opportunities and challenges.

Multi-Omics Analyses Reveal the Mechanisms of Early Stage Kidney Toxicity by Diquat

Diquat (DQ), a widely used bipyridyl herbicide, is associated with significantly higher rates of kidney injuries compared to other pesticides. However, the underlying molecular mechanisms are largely unknown. In this study, we identified the molecular changes in the early stage of DQ-induced kidney damage in a mouse model through transcriptomic, proteomic and metabolomic analyses. We identified 869 genes, 351 proteins and 96 metabolites that were differentially expressed in the DQ-treated mice relative to the control mice (p < 0.05), and showed significant enrichment in the PPAR signaling pathway and fatty acid metabolism. Hmgcs2, Cyp4a10, Cyp4a14 and Lpl were identified as the major proteins/genes associated with DQ-induced kidney damage. In addition, eicosapentaenoic acid, linoleic acid, palmitic acid and (R)-3-hydroxybutyric acid were the major metabolites related to DQ-induced kidney injury. Overall, the multi-omics analysis showed that DQ-induced kidney damage is associated with dysregulation of the PPAR signaling pathway, and an aberrant increase in Hmgcs2 expression and 3-hydroxybutyric acid levels. Our findings provide new insights into the molecular basis of DQ-induced early kidney damage.

Case series: Diquat poisoning with acute kidney failure, myocardial damage, and rhabdomyolysis

Diquat is a herbicide that can have deleterious effects on the kidneys, liver, heart, lungs, and central nervous system on ingestion. Diquat poisoning-associated rhabdomyolysis has rarely been reported. We describe two cases of diquat poisoning with acute renal failure, myocardial damage, and rhabdomyolysis. Case 1: A 17-year-old man experienced anuria after ingesting ~200 mL of diquat 16 h prior. On admission, his creatinine (400 μmol/L), urea (11.7 mmol/L), creatine kinase (2,534 IU/L), and myohemoglobin (4,425 ng/mL) concentrations were elevated. Case 2: An 18-year-old woman who ingested ~200 mL of diquat 5.5 h prior to admission had normal creatinine, urea, and creatine kinase concentrations. Eleven hours after ingestion, she developed anuria with elevated creatinine (169 μmol/L) concentration; her creatine kinase (13,617 IU/L) and myohemoglobin (>3,811 ng/mL) concentrations were remarkably elevated 24 h after ingestion. Both patients also had elevated aminotransferase and myocardial enzyme concentrations. After undergoing hemoperfusion and hemofiltration, blood diquat concentrations in cases 1 and 2 on admission (16/6 h after ingestion), after hemoperfusion (20/11 h after ingestion), and after 8 h of hemofiltration/8 h of hemofiltration and 2 h of hemoperfusion (29/21 h after ingestion) were 4.9/9.1, 3.4/5.4, and 1.5/1.2 μg/mL, respectively. Severe diquat poisoning can cause acute kidney failure and rhabdomyolysis. Rhabdomyolysis may induce myocardial injury, aggravating kidney damage, and also increase transaminase concentration. Hemoperfusion and hemofiltration could be effective treatments for eliminating diquat in the blood.

Methemoglobinemia and Delayed Encephalopathy After 5-Bromo-2-Nitropyridine Poisoning: A Rare Case Report

5-bromo-2-nitropyridine, an intermediate in the synthesis of pharmaceutical and pesticide products, is toxic to the human body. However, 5-bromo-2-nitropyridine poisoning has not been previously reported. Here, we report the case of a 40-year-old man who suffered skin and respiratory tract exposure to leaked 5-Bromo-2-nitropyridine at work. After exposure, the patient rapidly developed dizziness, fatigue, nausea, vomiting, chest distress, diffuse cyanosis, and coma. Methemoglobinemia, hemolytic anemia, rhabdomyolysis, and acute renal failure were observed after admission. He improved markedly after treatment, but delayed encephalopathy was confirmed 82 days after the exposure. This case highlights that 5-bromo-2-nitropyridine can be absorbed through the skin and respiratory tract, resulting in methemoglobinemia and delayed encephalopathy.

Diquat Poisoning: Care Management and Medico-Legal Implications

Acute chemical intoxication represents one of the major causes of Emergency Room admittance, and possible errors in diagnosis are extremely frequent, especially when patients present generic and non-specific symptoms. Diquat, a bipyridyl class of herbicides, exerts high intrinsic toxicity as a consequence of free oxygen radicals, leading to cellular death and organ dysfunctions. Following ingestion, with the major source of absorption for suicidal purposes, the chemical induces local irritating effects; systemic symptoms appear later, while specific symptoms can occur in the following 48 h. A smoker and hypertensive 50-year-old man arrives at the E.R., reporting that an episode of herbicide inhalation occurred few hours earlier. Physical examination evidenced alkalosis with hypoxemia, leucocytosis, mild hyperglycaemia and moderate increase in creatine kinase and myoglobin. Despite blood creatine kinase and myoglobin values that were higher than normal, he was prescribed with hydration and anti-pain therapy. During the night, the man left the hospital; he returned the next morning at 8:45 a.m., with cardiorespiratory arrest, medium fixed non-reactive mydriasis, diffused cyanosis of the skin and of the mucous membranes, as well as imperceptible pulse and peripheral pressure. Despite resuscitation attempts, the patient died at 9:30 a.m.; the body was immediately transferred to the morgue. Autopsy and toxicological analyses were carried out nine days later, evidencing paraquat ingestion for suicidal purposes. GC/MS analyses to verify the presence of diquat were performed on body fluids and gastric and colon contents; all specimens resulted positive, thus confirming the cause of death as herbicide ingestion (blood diquat concentration of 1.2 mg/L; more than twice the minimum to observe a systemic poisoning). The procedure followed for patient management resulted to be not in line with the provisions of both guidelines and good clinical practices. Staff did not perform clinical-diagnostical monitoring of the patient's condition or ask for more specific analyses (i.e., serum creatine phosphokinase monitoring). This misconduct led to a decrease in the patient's chances to survive.