Severe Paraquat Poisoning Research Articles

Favorable evolution of severe paraquat poisoning. Treatment with gastric lavage, activated charcoal, cyclophosphamide + corticoids, and conventional daily hemodialysis: case study at the Franck Joly Hospital Center in French Guiana

We report the observations of two patients, having voluntarily ingested lethal doses of paraquat with suicidal intent, with an unfavorable prognostic score. The treatment consisted of gastric lavage, administration of activated charcoal, n-acetylcysteine and cyclophosphamide + methylprednisolone + dexamethasone. The installation of acute renal failure motivated the initiation of daily conventional hemodialysis (HD) over 10 to 14 days, with a favorable evolution. The following complications were recorded: anemia, bacteremia and deep vein thrombosis. These observations raise three questions in the treatment of paraquat intoxication: the effectiveness of HD, the interest of its association with the above therapies in the prevention of pulmonary fibrosis, and the need for infectious prevention and thromboembolism. Furthermore, the absence of a paraquatemia assay cannot constitute a limitation for management, and hemoperfusion on an inaccessible charcoal column can be replaced by an HD usually available.

Phoenix Rising from the Ashes: A Story of Successful Management of a Severe Paraquat Poisoning

Self-poisoning with pesticides is a major public health problem in many developing countries, accounting for up to one-third of all suicides worldwide according to recent estimates and Sri Lanka is not an exception. Here we reporting a case of paraquat poisoning in a 17-year-old-girl presented after self-ingestion. She developed oropharyngeal ulcers and clinical and laboratory evidence of multi organ damage. She was successfully treated with cyclophosphamide and steroid, initiated very early stage in addition to other supportive measurers. She made an uneventful recovery.

Immunosuppressive drugs to reduce the mortality rate in patients with moderate to severe paraquat poisoning: A Meta-analysis.

The benefits and adverse effects of immunosuppressive drugs (ISDs) in patients with paraquat (PQ) poisoning have not been thoroughly assessed. This meta-analysis study aims to evaluate the effect of ISDs in patients with moderate to severe PQ poisoning. We searched PubMed, Embase, Cochrane Library, Ovid Medline, CNKI and Wanfang Data from inception to January 2019. The Mantel-Haenszel method with a random-effects model was used to calculate the pooled relative risks (RRs) and 95% Confidence Intervals (CIs) as described by DerSimonian and Laird. An L'Abbé plot was drawn to explore the relationship between the degree of poisoning and mortality. Four randomized controlled trials, two prospective and seven retrospective studies were identified. ISDs were significantly associated with reduced mortality (RR 0.76; 95% CI, 0.58-0.99) and the incidence rate of multiple-organ dysfunction syndrome (MODS) (RR 0.63; 95% CI, 0.48-0.83) in patients with moderate to severe PQ poisoning. They were not associated with an increased incidence rate of hepatitis and reduced incidence rate of acute renal failure and hypoxia. The L'Abbé plot results showed a slight increase in mortality rate in the ISD group with increased mortality in the placebo group. This indicates a possible advantage of ISDs in most of the patients with severe PQ poisoning. These findings suggest that ISDs may reduce the mortality and incidence rate of MODS in moderate to severe PQ poisoning patients, and severe PQ poisoning patients might benefit more from ISDs.

Effect of activated charcoal hemoperfusion on renal function in patients with paraquat poisoning.

The present study retrospectively analyzed 19 patients diagnosed with paraquat (PQ) poisoning with the aim to investigate the effect of activated charcoal hemoperfusion on renal function and PQ elimination. The results indicated that 7 patients died and 12 survived. Non-oliguric renal failure occurred in all of the 7 patients who died. Among the 12 surviving patients, 10 had normal renal function and 2 developed non-oliguric renal failure. There was a linear correlation between plasma and urine paraquat concentration prior to and during activated charcoal hemoperfusion. The equation parameters together with the correlation coefficient on admission were as follows: Y=0.5820+1.7348X (R2=0.678; F=35.768; P<0.0001). The equation parameters together with the correlation coefficient were as follows during activated charcoal hemoperfusion: Y=0.6827+1.2649X (R2=0.626; F=50.308; P<0.0001). Therefore, it was concluded that in patients with normal renal function, the elimination kinetics of PQ by the kidneys were only associated with the plasma PQ concentration. Activated charcoal hemoperfusion had little effect on avoiding acute kidney injury in patients with severe PQ poisoning.

Accidental Death Due to Pulmonary Fibrosis and Multiorgan Failure After Paraquat Ingestion: A Case Report

SESSION TITLE: Diffuse Lung Disease Case Report Posters SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM INTRODUCTION: Paraquat is a bipyridal herbicide that confers almost certain mortality with ingestion over 15 mL. Paraquat is sequestered by the body into lung tissues and the primary mechanism of death is pulmonary inflammation and fibrosis leading to refractory hypoxic respiratory failure. CASE PRESENTATION: A 65 year-old male presented to our Emergency department with complaints of nausea, emesis and mouth burning. The patient reported that he has accidentally ingested approximately 10 cc of commercial grade “Round Up” that he had purchased in an unlabeled Pepsi bottle from a neighbor. Physical exam, vital signs, and laboratory values were normal at that time and the patient was discharged home with a prescription for Zofran. 48 hours later the patient re-presented with progressive weakness, shortness of breath, and mouth blisters. Evaluation revealed low grade fever, tachycardia, hypotension, acute renal failure, and acute hypoxic respiratory failure. He was admitted to our intensive care unit and placed on Bipap. Despite salvage treatments, the patient suffered from progressive respiratory and renal failure and died on comfort measures after 5 days. DISCUSSION: Given the rarity of this case, there is sparse literature on management and treatment. Supplemental oxygen in fact exacerbates paraquat induced free radical toxicity thus creating a clinical conundrum. Experts suggest withholding supplemental oxygen until partial pressure of arterial oxygen falls below 50. There is no treatment for paraquat ingestion; however very limited data from clinical trials in Taiwan suggest a mortality benefit with pulse Cyclophosphamide and Solumedrol in selected patients. Urine paraquat levels can be obtained on admission and are known to correlate with severity of prognosis and may have helped guide appropriateness/futility of treatment interventions if they had been obtained in our patient. CONCLUSIONS: This was a devastating accidental death; clinicians should be aware of detrimental effects of ingestion of these agents and the importance of close collaboration with poison control toxicologist. Pertinent diagnostic and treatment tools will be reviewed. Reference #1: Lin Ja-Liang, et al. “Repeated pulse of methylprenisolone and cyclophosphamide with continuous dexamethasone therapy for patients with severe paraquat poisoning.” Crit Care Med 2006; 34(2):368-373. Reference #2: Hoffman, Robert et al. “Herbicides” GoldFranks Toxicologic Emergencies. McGraw Hill, 8th edition; 1544-55. DISCLOSURE: The following authors have nothing to disclose: Lauren Angotti No Product/Research Disclosure Information

Successful extracorporeal membrane oxygenation therapy as a bridge to sequential bilateral lung transplantation for a patient after severe paraquat poisoning

Context. Paraquat is a widely used herbicide that can cause severe to fatal poisoning in humans. The irreversible and rapid progression of pulmonary fibrosis associated with respiratory failure is the main cause of death in the later stages of poisoning. There are infrequent reports of successful lung transplants for cases of severe paraquat poisoning. We expect that this successful case will provide a reference for other patients in similar circumstances. Case details. A 24-year-old female was sent to the hospital approximately 2 hours after ingesting 50 ml of paraquat. She experienced rapidly aggravated pulmonary fibrosis and severe respiratory failure. On the 34th day after ingestion, she underwent intubation and invasive mechanical ventilation. The patient was evaluated for lung transplantation, and veno-venous extracorporeal membrane oxygenation (ECMO) was established as a bridge to lung transplantation on the 44th day. On the 56th day, she successfully underwent a bilateral sequential lung transplantation. Through respiratory and physical rehabilitation and nutrition support, the patient was weaned from mechanical ventilation and extubated on the 66th day. On the 80th day, she was discharged. During the 1-year follow-up, the patient was found to be in good condition, and her pulmonary function improved gradually. Conclusion: We suggest that lung transplantation may be an effective treatment in the end stages of paraquat-induced pulmonary fibrosis and consequential respiratory failure. For patients experiencing a rapid progression to a critical condition in whom lung transplantation cannot be performed immediately (e.g., while awaiting a viable donor or toxicant clearance), ECMO should be a viable bridge to lung transplantation.

Kidney damage biomarkers detect acute kidney injury but only functional markers predict mortality after paraquat ingestion

Acute kidney injury (AKI) is common following paraquat ingestion. The diagnostic performance of injury biomarkers was investigated in serial blood and urine samples from patients from 5 Sri Lankan hospitals. Functional AKI was diagnosed using serum creatinine (sCr) or serum cystatin C (sCysC). The 95th centile in healthy subjects defined the urinary biomarker cutoffs for diagnosing structural AKI. 50 poisoned patients provided 2 or more specimens, 76% developed functional AKI [AKIN stage 1 (n=12), 2 (n=7) or 3 (n=19)]; 19/26 patients with AKIN stage 2/3 also had functional AKI by sCysC criteria (≥50% increase). Urinary cystatin C (uCysC), clusterin (uClu) and NGAL (uNGAL) increased within 24h of ingestion compared with NoAKI patients and healthy controls. Each biomarker demonstrated moderate diagnostic utility [AUC–ROC: uCysC 0.79, uNGAL 0.79, uClu 0.68] for diagnosis of functional AKI at 16h. Death occurred only in subjects with functional AKI. Structural biomarker-based definitions detected more AKI than did sCr or sCysC, but did not independently predict death. Renal injury biomarkers did not add clinical value to patients who died rapidly due to multi-organ failure. Use of injury biomarkers within 16–24h may guide early intervention for reno-protection in less severe paraquat poisoning.

Efficacy and safety of pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide in patients with paraquat poisoning: A meta-analysis

Paraquat (PQ) is widely used in developing countries. Accidental or suicidal PQ poisoning is a public health concern due to lack of effective treatment. Because the role of pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide for PQ poisoning is uncertain, we performed a meta-analysis to investigate the efficacy and safety of the therapy. A systematic literature search for randomized controlled trials (RCTs) and other clinical studies was performed in Pub Med, Embase, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature and Retrieval System, and Chinese Medical Current Contents. We estimated pooled relative risk ratios (RRs) and 95% confidence intervals (CIs) using a fixed effect model or random effect model. Outcomes included mortality, incidence of acute renal failure (ARF) and hypoxia, and leucopenia. Five studies (three RCTs) involving 332 PQ poisoning patients met the criteria. The mortality of moderate to fulminant poisoning patients receiving the pulse therapy was lower than that of the controls (60.4% vs. 85.3%; RR 0.71, 95% CI: 0.59, 0.86, P=0.0004). The therapy also reduced the mortality of patients with moderate to severe PQ poisoning (45.1% vs. 79.1%, RR 0.45; 95% CI: 0.28, 0.75, P=0.002). However, the therapy did not decrease the incidence of ARF and hypoxia. In addition, the pulse therapy caused more leucopenia than the controls (36.9% vs. 2.6%; RR: 9.12; 95% CI: 3.65, 22.81, P<0.00001). Pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide may reduce the mortality of PQ poisoning patients, although the therapy may cause leucopenia.

Glucocorticoid with cyclophosphamide for paraquat-induced lung fibrosis.

Paraquat is an effective and widely used herbicide but is also a lethal poison. In many developing countries paraquat is widely available and inexpensive, making poisoning prevention difficult. However most of the people who become poisoned from paraquat have taken it as a means of suicide.Standard treatment for paraquat poisoning both prevents further absorption and reduces the load of paraquat in the blood through haemoperfusion or haemodialysis. The effectiveness of standard treatments is extremely limited.The immune system plays an important role in exacerbating paraquat-induced lung fibrosis. Immunosuppressive treatment using glucocorticoid and cyclophosphamide in combination is being developed and studied. To assess the effects of glucocorticoid with cyclophosphamide on mortality in patients with paraquat-induced lung fibrosis. The most recent search was run on the 15th April 2014. We searched the Cochrane Injuries Group's Specialised Register, The Cochrane Library, Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R), Embase Classic+Embase (Ovid), ISI WOS (SCI-EXPANDED, SSCI, CPCI-S & CPSI-SSH), trials registries, Chinese databases (, , ) and reference lists. RCTs were included in this review. All patients were to receive standard care, plus the intervention or control. The intervention was glucocorticoid with cyclophosphamide in combination versus a control of a placebo, standard care alone or any other therapy in addition to standard care. The mortality risk ratio (RR) and 95% confidence interval (CI) was calculated for each study on an intention-to-treat basis. Data for all-cause mortality at final follow-up were summarised in a meta-analysis using a fixed-effect model. This systematic review includes three trials with a combined total of 164 participants who had moderate to severe paraquat poisoning. Patients who received glucocorticoid with cyclophosphamide in addition to standard care had a lower risk of death at final follow-up than those receiving standard care only (RR 0.72; 95% CI 0.59 to 0.89). Based on the findings of three small RCTs of moderate to severely poisoned patients, glucocorticoid with cyclophosphamide in addition to standard care may be a beneficial treatment for patients with paraquat-induced lung fibrosis. To enable further study of the effects of glucocorticoid with cyclophosphamide for patients with moderate to severe paraquat poisoning, hospitals may provide this treatment as part of an RCT with allocation concealment.

English

Paraquat poisoning is characterized by multi-organ failure and pulmonary fibrosis with respiratory failure, resulting in high mortality and morbidity. To serious paraquat patients, the effectiveness of conventional treatments is unsuccessful. Whole lung lavage is a technique that was developed in the 1960s with the purpose of removing lipoproteinaceous material that accumulates in the bronchi of patients with alveolar proteinosis, leading to clinical and functional improvement. Pneumoconioses are characterized as irreversible, progressive respiratory diseases. No effective therapy exists to prevent progression of these diseases. Whole lung lavage might limit the rate of disease progression through the removal of dust, inflammatory cells, and cytokines. Whole lung lavage is also used successfully to treat other lung diseases such as endogenous lipoid pneumonia and mineral oil lipoid pneumonia. Paraquat poisoning could not be controlled by only one method and combined therapies are needed. So, we hypothesized that whole lung lavage will provide a new therapy of acute lung injury caused by paraquat. On the base of conventional therapy for paraquat poisoning, whole lung lavage could be considered in the early time of poisoning and then followed by glucocorticoid for patients with moderate to severe paraquat poisoning. Key words: Paraquat, poisoning, acute lung injury, whole lung lavage.

A case report of acute severe paraquat poisoning and long-term follow-up.

In the present study, the successful management of severe paraquat (PQ) poisoning with multiple organ dysfunction syndrome is described. A 42-year-old female ingested >100 ml PQ (20% weight/volume) in an attempted suicide. After 22 h the patient was admitted to hospital with serious liver, kidney and lung damage. Comprehensive therapy that maximized poison elimination was administered, along with appropriate glucocorticoids and medication for anticoagulation and protection of the liver and kidney. The patient was successfully treated and recovered after 40 days. However, pulmonary damage was aggravated when the glucocorticoid treatment was stopped after 2 months; the lungs recovered again following systematic therapy. Subsequent to a 8-month follow-up, the patient was able to look after herself in her daily life. To the best of our knowledge, successful treatment following severe PQ poisoning is rare.

Improved survival in severe paraquat poisoning with repeated pulse therapy of cyclophosphamide and steroids

To clarify the efficacy of repeated methylprednisolone (MP) and cyclophosphamide (CP) pulse therapy and daily dexamethasone (DEX) therapy in patients with severe paraquat (PQ) poisoning. A total of 111 patients with severe PQ poisoning and dark-blue color in urine tests within 24 h of intoxication were included prospectively. The control group consisted of 52 patients who were admitted between 1998 and 2001 and who received high doses of CP (2 mg/kg per day) and DEX (5 mg every 6 h) for 14 days. The study group consisted of 59 patients who were admitted from 2002 to 2007 and who received initial MP (1 g) for 3 days and CP (15 mg/kg per day) for 2 days, followed by DEX (5 mg every 6 h) until a PaO(2) of >80 mmHg had been achieved, or treated with repeated 1 g MP for 3 days and 1 g CP for 1 day if the PaO(2) was <60 mmHg. There were no differences between the two groups with regard to baseline data and plasma PQ levels. The study group patients had a lower mortality rate (39/59, 66%) than the control group patients (48/52, 92%; P=0.003, log-rank test). Multivariate Cox regression analysis revealed that the repeated pulse therapy was correlated with decreased hazard ratios (HR) for all-cause mortality (HR=0.50, 95% CI 0.31-0.80; P=0.004) and death from lung fibrosis-related hypoxemia (HR=0.10, 95% CI 0.04-0.25; P<0.001) in severely PQ-intoxicated patients. Repeated pulses of CP and MP, rather than high doses of CP and DEX, may result in a lower mortality rate in patients with severe PQ poisoning.

Intoxicação grave por paraquat: achados clínicos e radiológicos em um sobrevivente

Paraquat is a nonselective contact herbicide of great toxicological importance, being associated with high mortality rates, mainly due to respiratory failure. We report the case of a 22-year-old male admitted to the emergency room with a sore throat, dysphagia, hemoptysis, and retrosternal pain after the ingestion of 50 mL of a paraquat solution, four days prior to admission. Chest CT scans revealed pulmonary opacities, pneumomediastinum, pneumothorax, and subcutaneous emphysema. The patient was submitted to two cycles of immunosuppressive therapy with cyclophosphamide, methylprednisolone, and dexamethasone. The pulmonary gas exchange parameters gradually improved, and the patient was discharged four weeks later. The clinical and tomographic follow-up evaluations performed at four months after discharge showed that there had been further clinical improvement. We also present a brief review of the literature, as well as a discussion of the therapeutic algorithm for severe paraquat poisoning.

Successful Treatment of Paraquat Poisoning by Xuebijing, an Injection Concocted from Multiple Chinese Medicinal Herbs: A Case Report

1,1'-Dimethyl-4,4'-bipyridinium dichloride (Paraquat) poisoning remains a significant global health problem. Despite noteworthy research and clinical efforts worldwide in the last few decades, little improvement has been made in reducing fatality from Paraquat poisoning with conventional treatment strategies. We herein report a case of successful management of Paraquat poisoning by Xuebijing, a newly developed injection concocted from multiple traditional Chinese medicinal herbs. A 25-year-old male patient was brought to the Emergency Department at the First Affiliated Hospital of Jilin University in Changchun, China approximately 23 hours after ingestion of approximately 50 mL of 20% (w/v) Paraquat in a suicide attempt. On admission, the patient presented with clinical symptoms as well as significantly abnormal results in the liver and kidney function tests that were typical of severe Paraquat poisoning. Following the routine emergency procedures for pesticide poisoning to minimize the poison exposure and relieve the poisoning symptoms, an intravenous drip of Xuebijing together with dexamethasone was given daily to the patient until discharge 10 days after admission. The patient was followed up for 15 months after discharge, during which monthly chest radiography was performed. Treatment outcomes: At the time of discharge, the patient had recovered well: His symptoms of poisoning in the mouth and gastrointestinal tract were all diminishing; his liver and kidney functions were recovering with the major test parameters improving; his chest radiograph was clear, showing no signs of pulmonary fibrosis. During the postdischarge follow-up period, the monthly chest radiographs were all normal. This case report suggests that Xuebijing has great potential as a novel effective alternative to the conventional management of Paraquat poisoning. This potential needs to be further evaluated in a substantially larger number of clinical cases in the future.

The effectiveness of combined treatment with methylprednisolone and cyclophosphamide in oral paraquat poisoning.

Paraquat is a bipyridil herbicide and in appropriate and careful usage, will not be health threatening. Most adult cases of intoxication are due to suicidal attempts rather than accidental exposure. Therapeutic response has been reported to be appropriate with high doses of cyclophosphamide and glucocorticoids and survival is reported to be approximately 75%. So, this study was designed to evaluate the effects of combined treatment with cyclophosphamide and glucocorticoids in patients with paraquat poisoning. During a two-year period 45 patients with paraquat poisoning were admitted to Sina Hospital, Hamadan, Iran, of whom 20 had moderate to severe intoxication. Eleven patients (group 1) received conventional treatment and nine patients (group 2) received conventional treatment plus intravenous infusions of cyclophosphamide 15 mg/kg daily for two days, methylprednisolone one gram daily for three days, and mesna 15 mg/kg for four days. The mean age+/-SD in group 1 was 25+/-10 years and in group 2 was 26+/-10 years. In group 1 three patients were females and eight patients were males. In group 2 one patient was female and eight patients were males. There were no differences between the groups in the time elapsed from ingestion to presentation at hospital or in the beginning of hemodialysis. The mortality rate in group 1 was 81.8% and in group 2 was 33.3% (P< 0.05). All fatalities caused by acute respiratory distress syndrome. Pulse therapy with cyclophosphamide and methylprednisolone may be effective in preventing respiratory failure and reducing mortality in patients with moderate to severe paraquat poisoning.

Repeated pulse of methylprednisolone and cyclophosphamide with continuous dexamethasone therapy for patients with severe paraquat poisoning

Paraquat is widely used in the world, and all treatments for paraquat poisoning have been unsuccessful. Many patients have died of paraquat poisoning in developing countries. A novel anti-inflammation method was developed to treat severe paraquat-poisoned patients with >50% to <90% predictive mortality: initial pulse therapy with methylprednisolone (1 g/day for 3 days) and cyclophosphamide (15 mg/kg/day for 2 days), followed by dexamethasone 20 mg/day until Pao2 was >11.5 kPa (80 mm Hg) and repeated pulse therapy with methylprednisolone (1 g/day for 3 days) and cyclophosphamide (15 mg/kg/day for 1 day), which was repeated if Pao2 was <8.64 kPa (60 mm Hg). Randomized controlled trial. Academic medical center in Taiwan. Twenty-three paraquat-poisoned patients with >50% and <90% predictive mortality assessed by plasma paraquat levels were prospectively and randomly assigned to the control and study groups at a proportion of 1:2. The control group received conventional therapy and the study group received the novel repeated pulse treatment with long-term steroid therapy. We measured patient mortality during the study period. There was not a different distribution of basal variables between the two study groups. The mortality rate (85.7%, six of seven) of the control group was higher than that of the study group (31.3%, five of 16; p = .0272). The novel anti-inflammatory therapy reduces the mortality rate for patients with severe paraquat poisoning.

Pulse therapy with cyclophosphamide and methylprednisolone in patients with moderate to severe paraquat poisoning: a preliminary report.

Severe paraquat poisoning causes considerable morbidity and mortality. High doses of cyclophosphamide and dexamethasone have been used to treat patients with paraquat poisoning, but with mixed results. The use of pulse methylprednisolone and cyclophosphamide was investigated in the treatment of moderately severe paraquat poisoning. During a six-year period 87 patients with paraquat poisoning were admitted to hospital, of whom 33 had moderate to severe intoxication. Seventeen patients received conventional treatment and served as historical controls, and 16 received intravenous infusions of cyclophosphamide 1 g daily for two days and methylprednisolone 1 g daily for three days. There were no differences between the groups in age, sex, severity of paraquat poisoning (as assessed by urine dithionite tests), or in the time elapsed from ingestion to presentation at hospital or to the beginning of haemoperfusion. No differences were seen in biochemical measurements on the third day after paraquat poisoning. The mortality in the pulse therapy group was lower than that in the control group (4/16 (25%) versus 12/17 (70.6%), p = 0.01). All fatalities were from progressive respiratory failure. Pulse therapy with cyclophosphamide and methylprednisolone may be effective in preventing respiratory failure and reducing mortality in patients with moderate to severe paraquat poisoning. Further controlled studies are needed to confirm this and to establish the mechanisms.

Hemoperfusion versus Hemodialysis in the Management of Patients Severely Poisoned by Organophosphorus Insecticides and Bipyridyl Herbicides

ABSTRACTOrganophosphorus insecticides (parathion, demeton‐S‐methyl sulfoxide, dimethoate) inhibit cholinesterase activity. Besides the well‐known resulting biochemical changes, there is evidence of direct toxic effects due to an excess of organophosphorus in blood and tissue. The therapeutic measure described here aims at eliminating organophosphorus.Hemodialysis (HD) has no effect in parathion poisoning, but hemoperfusion with coated activated charcoal (HP‐CHAR) results in a clearance of 59.20% of the blood flow (ml/min) while the HP clearance with Amberlite XAD‐4 (HP‐XAD) is 81.33%. HD may be used in poisoning by demeton‐S‐methyl sulfoxide (clearance: 52.98%), and dimethoate (clearance: 59.07%), but HP‐CHAR clearance is much higher (83.70% and 87.84%, respectively). HP‐XAD clearance even reaches 100% of the blood flow.Demeton‐S‐methyl sulfoxide and dimethoate are distributed almost equally in blood and tissue, and the effect of HP is indicated by a rapid decline in blood organophosphorus level as well as by an improvement in the signs and symptoms of the patient. Parathion accumulation is six to eight times higher in the tissue. This means there is protracted decline in blood level because of redistribution and less clinical evidence of improvement. However, animal trials demonstrate that HP‐CHAR results in a significantly faster decrease in parathion concentration in muscle and brain as compared with the control group. Hence, HP is an effective method for removing toxicologically relevant amounts of organophosphorus from the body.Oral poisoning with bipyridyl herbicides such as paraquat (Gramoxone®) and diquat (Reglone®) is extremely serious. Fatal consequences occur after even one to three mouthfuls of the commercial liquid preparations. The literature reports that patients whose plasma levels within the first 48 hours exceed 0.1‐0.2 μg/ml have died, regardless of therapy. Recently, two patients with severe suicidal poisonings were treated by almost continuous HP (and HD) using 12 and 21 columns, respectively, for a period of two to three weeks. Paraquat plasma levels were 1.12 μg/ml and 1.44 μg/ml, respectively, within the first 48 hours after ingestion. Both patients survived without lung damage.HP‐CHAR clearance (72.7 ml/min, blood flow 100 ml/min) clearly exceeds that of HD (11.5 ml/min, blood flow 100 ml/min) at these blood levels. Probably the affinity of coated activated charcoal for paraquat is superior to that of lung tissue. Hence, continuous HP‐CHAR is recommended in severe paraquat poisoning.