Treatment of the cardiovascular manifestations of phosphine poisoning with trimetazidine, a new antiischemic drug

Pesticidal Toxicity of Phosphine and Its Interaction with Other Pest Control Treatments

Phosphine is the most widely used fumigant for stored grains due to a lack of better alternatives, all of which have serious shortcomings that restrict their use. The extensive use of phosphine has led to the development of resistance among insect pests of grain, which threatens its status as a reliable fumigant. Understanding the mode of action of phosphine as well as its resistance mechanisms provides insight that may lead to improved phosphine efficacy and pest control strategies. The mechanisms of action in phosphine vary from disrupting metabolism and oxidative stress to neurotoxicity. Phosphine resistance is genetically inherited and is mediated by the mitochondrial dihydrolipoamide dehydrogenase complex. In this regard, laboratory studies have revealed treatments that synergistically enhance phosphine toxicity that may be used to suppress resistance development and enhance efficacy. Here, we discuss the reported phosphine modes of action, mechanisms of resistance and interactions with other treatments.

Reducing the risk of death induced by aluminum phosphide poisoning: The new therapies

Numerous people suffer from accidental or deliberate exposure to different pesticides when poisoning with aluminum phosphate (AlP) is increasing in the eastern countries. Aluminum phosphate is a conventional insecticide that quickly reacts with water or the moistures in the atmosphere and produces fatal phosphine gas, which absorbs quickly by the body. Oral consumption or inhalation of AlP leads to excessive reaction of the body such as fatigue, vomiting, fever, palpitation, vasodilatory shock, increasing blood pressure, cardiac dysfunction, pulmonary congestion, shortness of breath, and death. The garlic smell from the patient's mouth or exhale is one of the methods to recognize the positioning. Due to the lack of individual antidotes, several supportive treatments are required. The present study focused on the available and new therapies that help reduce the effect of AlP poisoning and the mortality rate. The therapies are divided into the antioxidant-related agent and the other agents. The impacts of each agent on the experimental cases are reported.

Successfully managed aluminum phosphide poisoning: A case report

INTRODUCTION

and Importance: Aluminum phosphide (ALP) is a commonly available pesticide in agricultural countries like Nepal. Upon ingestion, this releases highly toxic phosphine gas in the gastrointestinal tract when it comes in contact with humidity. This leads to refractory shock, metabolic acidosis, cardiac arrhythmia, renal failure, and hepato-biliary impairment.

CASE PRESENTATION

We present a successfully managed case of a 17-year-old girl who ingested 6 g (2 tablets) of ALP tablets with suicidal intent. Although the mortality has been reported as 70-100% with mere ingestion of 150-500 mg of ALP, this case survived even after developing severe metabolic acidosis, acute renal failure, refractory shock, and ventricular tachycardia.

CLINICAL DISCUSSION

ALP poisoning is most often lethal. However, there is an emerging evidence of successful use of various drugs such as magnesium sulfate, trimetazidine, and other interventions such as intra-aortic balloon pump and extra corporeal membrane oxygenation in case of ALP poisoning.

CONCLUSION

Owing to the unavailability of an effective antidote of ALP to date, we emphasize early initiation of supportive management, intensive monitoring, and potential role of membrane stabilizers like magnesium sulfate, and cardio-protective agents like trimetazidine, N-Acetyl cysteine, thiamine, vitamin C, and hydrocortisone in decreasing the likelihood of fatal outcome.

Antidotal effect of dihydroxyacetone against phosphine poisoning in mice

Phosphine (PH₃ ) is widely used as an insecticide and rodenticide. On the contrary, many cases of PH₃ poisoning have been reported worldwide. Unfortunately, there is no specific antidote against PH₃ toxicity. Disruption of mitochondrial function and energy metabolism is a well-known mechanism of PH₃ cytotoxicity. Dihydroxyacetone (DHA) is an adenosine triphosphate supplying agent which significantly improves mitochondrial function. The current study was designed to evaluate DHA's effect on inhalational PH₃ poisoning in an animal model. DHA was injected into BALB/c mice before and/or after the start of the PH₃ inhalation. The cytochrome c oxidase activity was assessed in the animals' brain, heart, and liver exposed to PH₃ (for 15, 30, and 60 min, with and without the antidote). The LC₅₀ of PH₃ was calculated to be 18.02 (15.42-20.55) ppm over 2 h of exposure. Pretreatment of DHA (1 or 2 g/kg) increased the LC₅₀ of PH₃ by about 1.6- or 3-fold, respectively. Posttreatment with DHA (2 g/kg) increased the LC₅₀ of PH₃ by about 1.4-fold. PH₃ inhibited the activity of cytochrome c oxidase in the assessed organs. It was found that DHA treatment restored mitochondrial cytochrome c oxidase activity. These findings suggested that DHA could be an effective antidote for PH₃ poisoning.

Successful management of zinc phosphide poisoning-a Hungarian case

BACKGROUND

Zinc phosphide (ZnP) is the basic component of several insecticides easily accessible worldwide. Intentional or accidental intoxication may lead to severe complications and multiple organ failure, resulting in high mortality. No known antidote is currently available. The iron-chelation and the antioxidative effects are well-known features of alpha-lipoic acid (ALA), although its use in the treatment of ZnP poisoning has not been documented previously. We describe the case of a patient with serious ZnP poisoning with multiple organ failure, where ALA was also included in the patient's supportive therapy.

CASE PRESENTATION

A 65-year-old man ingested 125 g of Arvalin® (containing 5 g ZnP) and presented to the Emergency Department, with respiratory insufficiency and decreased consciousness. He developed hypokalemia, hypocalcemia, low white blood cell count, elevated C-reactive protein level, mixed acidosis, hepatic and kidney damage, thickening of the jejunal wall, and lung atelectasis, which served as a basis for the ensuing bacterial pneumonia. Antibiotics and adequate supportive therapy were provided. Laboratory tests indicated liver damage (slightly increased liver enzymes, low pseudocholinesterase levels; 706 U/L on day 2), possibly caused by the patient's chronic alcoholism or the ZnP poison itself, therefore, hepatoprotective agents, ALA (Thiogamma Turbo-Set®) with N-acetylcysteine were administered for six consecutive days. Pseudocholinesterase values increased sixfold until the end of the second week of care. Fifteen days after admission, the patient was relocated to the department of psychiatry with stable vital functions, clear consciousness, declining inflammatory markers, and improved liver function. He was discharged 1 month later, fully recovered.

CONCLUSIONS

Our case is the first documented voluntary and severe ZnP poisoning in Hungary. Our patient developed multiple organ failure and atelectasis, possibly resulting in the observed respiratory infection. The development of bacterial pneumonia highlighted the dangers of phosphine-induced atelectasis. The use of ALA in our patient's case, as an antioxidant and agent for metal chelation, suggested that this agent could be a promising tool in the prevention and treatment of ZnP-induced hepatic damage.

STEMI in Young Befogged by Aluminum Phosphide Toxicity-Role of ECMO as Salvage Therapy and Trimetazidine and Magnesium to Suppress Arrhythmias

Introduction

Aluminum phosphide poisoning (ALP) has a high-mortality rate despite intensive care management, primarily because it causes severe myocardial depression. This case report highlights the subset of ALP patients presenting as ST elevation myocardial infarction (STEMI) with profound myocardial dysfunction and multiorgan failure and successfully treated with extracorporeal membrane oxygenation (ECMO), trimetazidine, and magnesium.

Case description

A 25-year-old man without any comorbidities was brought to emergency department with dyspnea and hypotension. His electrocardiograph (ECG) revealed STEMI with elevated troponin levels, arterial blood gas (ABG) showed severe metabolic acidosis, and echocardiography (echo) revealed ejection fraction 15%. He was initiated on venoarterial (VA) ECMO in view of refractory hypotension. History of consumption of three tabs of celphos was revealed later by the family members. He progressed to cardiogenic shock, arrhythmias, respiratory failure, acute kidney injury with severe lactic acidosis, liver injury, pancreatitis, and disseminated intravascular coagulation (DIC). He was successfully supported by ECMO, hemodialysis, magnesium, trimetazidine, N-acetyl cysteine, inotropes, and blood products. He was weaned off ECMO on day 6 and was discharged home on day 12. Despite his severe and confounding clinical presentation, he had complete normalization of end-organ dysfunction with no neurological sequela. This case demonstrates the high index of suspicion required for ALP, given the potential for rapid progression and severe multiorgan toxicity. This report also highlights the importance of early referral to a tertiary care center with ECMO capability and also the role of magnesium and trimetazidine to suppress arrhythmias.

Conclusion

Aluminum phosphide poisoning can present as STEMI with cardiogenic shock resulting in acute kidney injury, liver injury, pancreatitis, and DIC. Venoarterial ECMO provides an effective means of support until the recovery of organ function. Trimetazidine and magnesium are helpful in suppressing fatal arrhythmias. This report emphasizes that early recognition and early institution of ECMO can save many young lives who succumb to toxic effects of this poison.

How to cite this article

Rao CC, Himaaldev GJ. STEMI in Young Befogged by Aluminum Phosphide Toxicity—Role of ECMO as Salvage Therapy and Trimetazidine and Magnesium to Suppress Arrhythmias. Indian J Crit Care Med 2020;24(8):727–730.

Aluminium phosphide poisoning with severe cardiac dysfunction and the role of digoxin

Aluminium phosphide (ALP) is a common cause of suicidal poisoning in India where it is easily available and commonly known as 'rice tablet'. In rural areas of India, it is still used to protect rice and stored grains from rodents and pests. 1 There is no specific antidote for phosphide poisoning and treatment involves meticulous supportive care. Ingestion can lead to severe cardiac suppression and cardiogenic shock. For patients poisoned with ALP who continue to have refractory shock with persistent myocardial suppression despite the use of adrenergic inotropic agents, the addition of digoxin may be beneficial. We present a case where digoxin was utilised with beneficial patient outcomes.

The effect of N-acetyl cysteine (NAC) on aluminum phosphide poisoning inducing cardiovascular toxicity: a case-control study

Background

Aluminum phosphide (AlP) is a very effective indoor and outdoor pesticide. We investigated the effects of N-acetyl cysteine (NAC) on the survival time, hemodynamics, and cardiac biochemical parameters at various time intervals in some cases of AlP poisoning.

Methods

This research was a case–control study to evaluate 63 AlP poisoned patients during 2010–2012. Patients with cardiovascular complications of AlP to be treated with intravenous NAC plus conventional treatment were considered as the case group and compared with patients who did not receive NAC. NAC infusion was administered to the case group at 300 mg/kg for 20 h. The data gathered included age, sex, heart rate, Systolic blood pressure (SBP), creatine phosphokinase (CPK), creatine kinase MB (CK-MB), and ECG at the admission time and 12, 18, and 24 h after admission. Analysis of repeated measures was performed to check the variability of parameters over time.

Results

The mean ages in the case and control groups were 26.65 ± 1.06 (19–37 years) and 28.39 ± 1.11 (18–37 years), respectively (P = 0.266). Most of the patients were female (56.5%). CK-MB means were significantly different between the two groups, but no differences between the other variables were observed. Also, CK-MB, CPK, heart rate, and systolic blood pressure means became significantly different over time (0, 12, 18, and 24 h) in both groups (P < 0.001). NAC prevented sharp heart rate fluctuations in AlP patients in the case group. Regarding the outcomes, 17 patients died (10 patients in the control and 7 patients in the case groups). No side-effects of NAC were observed.

Conclusion

Our patients could be managed by the positive role of NAC as the biochemical index of cardiotoxicity was found to elevate in both the case and control groups. Therefore, for the management protocol optimization, NAC evaluation should be done in further cases.

Chemical Reaction between Boric Acid and Phosphine Indicates Boric Acid as an Antidote for Aluminium Phosphide Poisoning

OBJECTIVES

Aluminium phosphide (AlP) is a fumigant pesticide which protects stored grains from insects and rodents. When it comes into contact with moisture, AlP releases phosphine (PH3), a highly toxic gas. No efficient antidote has been found for AlP poisoning so far and most people who are poisoned do not survive. Boric acid is a Lewis acid with an empty p orbital which accepts electrons. This study aimed to investigate the neutralisation of PH3 gas with boric acid.

METHODS

This study was carried out at the Baharlou Hospital, Tehran University of Medical Sciences, Tehran, Iran, between December 2013 and February 2014. The volume of released gas, rate of gas evolution and changes in pH were measured during reactions of AlP tablets with water, acidified water, saturated boric acid solution, acidified saturated boric acid solution, activated charcoal and acidified activated charcoal. Infrared spectroscopy was used to study the resulting probable adduct between PH3 and boric acid.

RESULTS

Activated charcoal significantly reduced the volume of released gas (P <0.01). Although boric acid did not significantly reduce the volume of released gas, it significantly reduced the rate of gas evolution (P <0.01). A gaseous adduct was formed in the reaction between pure AlP and boric acid.

CONCLUSION

These findings indicate that boric acid may be an efficient and non-toxic antidote for PH3 poisoning.

Occupational exposure to aluminium phosphide and phosphine gas? A suspected case report and review of the literature

The manufacture and application of aluminium phosphide fumigants pose risks of inhalation exposure to phosphine gas. This article presents a case report of suspected inhalation exposure to phosphine gas in a manufacturing facility for aluminium phosphide fumigants, which was associated with acute dyspnoea, hypotension, bradycardia and other signs of intoxication. These symptoms resolved within several hours after removal from exposure. A review of the data on human exposures to phosphide fumigants identifies both pesticide applicators and individuals in the vicinity of application to be at risk of accidental exposure and injury from phosphine inhalation. More recent reports have identified risks of phosphine gas inhalation in association with the clandestine production of methamphetamine. Toxicodynamic effects of phosphine result from the inhibition of cytochrome c oxidase and subsequent generation of reactive oxygen species. There remain unanswered questions relating to the toxicokinetics of phosphine, as well as the assessment of human exposure utilizing biomarkers. As initial signs and symptoms of intoxication from phosphine gas may be nonspecific and transient, there is a need for improved recognition of the potential hazards associated with phosphide fumigants and phosphine gas.

Phosphine toxicity: a story of disrupted mitochondrial metabolism

Rodenticides and pesticides pose a significant threat not only to the environment but also directly to humans by way of accidental and/or intentional exposure. Metal phosphides, such as aluminum, magnesium, and zinc phosphides, have gained popularity owing to ease of manufacture and application. These agents and their hydrolysis by-product phosphine gas (PH3 ) are more than adequate for eliminating pests, primarily in the grain storage industry. In addition to the potential for accidental exposures in the manufacture and use of these agents, intentional exposures must also be considered. As examples, ingestion of metal phosphides is a well-known suicide route, especially in Asia; and intentional release of PH3 in a populated area cannot be discounted. Metal phosphides cause a wide array of effects that include cellular poisoning, oxidative stress, cholinesterase inhibition, circulatory failure, cardiotoxicity, gastrointestinal and pulmonary toxicity, hepatic damage, neurological toxicity, electrolyte imbalance, and overall metabolic disturbances. Mortality rates often exceed 70%. There are no specific antidotes against metal phosphide poisoning. Current therapeutic intervention is limited to supportive care. The development of beneficial medical countermeasures will rely on investigative mechanistic toxicology; the ultimate goal will be to identify specific treatments and therapeutic windows for intervention.

Molecular and biochemical evidence on the protection of cardiomyocytes from phosphine-induced oxidative stress, mitochondrial dysfunction and apoptosis by acetyl-L-carnitine

The aim of the present study was to investigate the efficacy of acetyl-L-carnitine (ALCAR) on pathologic changes of mitochondrial respiratory chain activity, ATP production, oxidative stress, and cellular apoptosis/necrosis induced by aluminum phosphide (AlP) poisoning. The study groups included: the Sham that received almond oil only; the AlP that received oral LD50 dose of aluminum; the AC-100, AC-200, and AC-300 which received concurrent oral LD50 dose of AlP and single 100, 200, and 300 mg/kg of ALCAR by intraperitoneal injection. After 24 h, the rats were sacrificed; the heart and blood sample were taken for measurement of biochemical and mitochondrial factors. The results specified that ALCAR significantly attenuated the oxidative stress (elevated ROS and plasma iron levels) caused by AlP poisoning. ALCAR also increased the activity of cytochrome oxidase, which in turn amplified ATP production. Furthermore, flow cytometric assays and caspase activity indicated that ALCAR prohibited AlP-induced apoptosis in cardiomyocytes.

Thoughts on the current management of acute aluminum phosphide toxicity and proposals for therapy: An Evidence-based review

The majority of aluminum phosphide (ALP) toxicity cases are suicidal attempts. Despite advances in critical care medicine, the mortality rate of ALP remains very high. Unfortunately, knowledge on the toxicokinetics of ALP is very low. An obsolete idea was proposed that inhibition of complex IV of cytochrome C oxidase is responsible for multiorgan dysfunction. However, based on human studies, this effect might be insignificant. Thus, a novel idea proposes that the main mechanism might be vascular wall integrity disruption. The low frequency of acute toxicity and unanswered questions about the toxicokinetics and toxicodynamics has led to leaden advances of novel treatments. The aim of this review was to evaluate problems regarding current treatment protocols and propose new ideas based on updated information. For this purpose, we reviewed all available articles on the management of ALP poisoning published to date. Considering failure of conventional therapies on maintaining systolic blood pressure, correcting acid-base disturbances, and support cardiac function, the previous treatment protocols have been overruled. However, repudiate of conventional treatments in this deadly condition is not without penalties for the health-care provider. The introduction of new therapies including refuse of gastric lavage with water-soluble compounds, administration of a high molecular weight colloidal solution for fluid resuscitation and termination using sodium bicarbonate, and vasoactive agents has been prospected to improve patient survival. This protocol is in early clinical evaluation; nevertheless, it appears to improve patient's survival; hence, future randomized trials should be performed to support their effectiveness.

Successful Management of Aluminium Phosphide Poisoning Resulting in Cardiac Arrest

Aluminum phosphide has high toxicity when it is ingested, and in case of contact with moisture, phosphine gas is released. Aluminum phosphide poisoning causes metabolic acidosis, arrhythmia, acute respiratory distress syndrome and shock, and there is no specific antidote. A 17-year-old male patient was referred to our hospital because of aluminum phosphide poisoning with 1500 mg of aluminum phosphide tablets. The patient's consciousness was clear but he was somnolent. Vital parameters were as follows: blood pressure: 85/56 mmHg, pulse: 88 beats/min, SpO2: 94%, temperature: 36.4°C. Because of hypotension, noradrenaline and dopamine infusions were started. The patient was intubated because of respiratory distress and loss of consciousness. Severe metabolic acidosis was determined in the arterial blood gas, and metabolic acidosis was corrected by sodium bicarbonate treatment. In addition to supportive therapy of the poisoning, haemodialysis was performed. Cardiac arrest occurred during follow-ups in the intensive care unit, and sinus rhythm was achieved after 10 min of cardiopulmonary resuscitation. The patient was discharged after three sessions of haemodialysis on the ninth day. As a result, haemodialysis contributed to symptomatic treatment of aluminum phosphide poisoning in this case report.

Aluminum phosphide poisoning: Possible role of supportive measures in the absence of specific antidote

Aluminum phosphide (ALP) poisoning is one of the major causes of suicidal deaths. Toxicity by ALP is caused by the liberation of phosphine gas, which rapidly causes cell hypoxia due to inhibition of oxidative phosphorylation, leading to circulatory failure. Treatment of ALP toxicity is mainly supportive as there is no specific antidote. We recently managed 7 cases of ALP poisoning with severe hemodynamic effects. Patients were treated with supportive measures including gastric lavage with diluted potassium permanganate, coconut oil and sodium-bicarbonate first person account should be avoided in a scientific paper. Intravenous magnesium sulfate, proper hemodynamic monitoring and vasopressors. Four out of 7 survived thus suggesting a role of such supportive measures in the absence of specific antidote for ALP poisoning.

Mitochondrial electron transport chain complexes, catalase and markers of oxidative stress in platelets of patients with severe aluminum phosphide poisoning

Aluminum phosphide (ALP), a widely used fumigant and rodenticide, leads to high mortality if ingested. Its toxicity is due to phosphine that is liberated when it comes in contact with moisture. The exact site or mechanism of action of phosphine is not known, although it is widely believed that it affects mitochondrial oxidative phosphorylation. Basic serum biochemical parameters, activity of mitochondrial complexes, antioxidant enzymes and parameters of oxidative stress were estimated in the platelets of 21 patients who developed severe poisoning following ALP ingestion. These parameters were compared with 32 healthy controls and with 22 patients with shock due to other causes (cardiogenic shock (11), septic shock (9) and hemorrhagic shock (2)). The serum levels of creatine kinase-muscle brain and lactate dehydrogenase were higher in patients poisoned with ALP, whereas a significant decrease was observed in the activities of mitochondrial complexes I, II and IV. The activity of catalase was lower but the activities of superoxide dismutase and glutathione peroxidase were unaffected in them. A significant increase in lipid peroxidation and protein carbonylation was observed, whereas total blood thiol levels were lower. In patients severely poisoned with ALP, not only cytochrome c oxidase but also other complexes are involved in mitochondrial electron transport, and enzymes are also inhibited.

Unreported cardiac arrhythmias in aluminium worker

Aluminium (Al) is the third most prevalent element, representing approximately 8% of total mineral components in the earth's crust (1). Chronic exposure to Al is mainly encountered at particular work places, for example, in foundries or in the Al powder industry, as an occupational exposure. In case of occupational Al exposure, inhalation is the main route of uptake. Chronic exposure to Al is associated with skeletal, neurological, hematological and lung changes. Studies regarding the Al powder industry showed that long-term inhalative exposure to Al can induce pulmonary fibrosis (2). Although there is only one report about ventricular tachycardia as a cardiac manifestation in occupationally exposed persons (3), in this report, we presented a case that had Mobitz type I second-degree atrioventricular block and nonsustained ventricular tachycardia. To our knowledge, this is the first report in chronic poisoning.

An update on toxicology of aluminum phosphide

Aluminum phosphide (AlP) is a cheap solid fumigant and a highly toxic pesticide which is commonly used for grain preservation. In Iran it is known as the “rice tablet”. AlP has currently aroused interest with increasing number of cases in the past four decades due to increased use in agricultural and non-agricultural purposesand also its easy availability in the markets has increased its misuse to commit suicide. Upon contact with moisture in the environment, AlP undergoes a chemical reaction yielding phosphine gas, which is the active pesticidal component. Phosphine inhibits cellular oxygen utilization and can induce lipid peroxidation. It was reported that AlP has a mortality rate more than 50% of intoxication cases. Poisoning with AlP has usually occurred in attempts to suicide. It is a more common case in adults rather than teen agers. In some eastern countries it is a very common agent with rapid action for suicide. Up to date, there is no effective antidote or treatment for its intoxication. Also, some experimental results suggest that magnesium sulfate, N-acetyl cysteine (NAC), glutathione, vitamin C and E, beta-carotenes, coconut oil and melatonin may play an important role in reducing the oxidative outcomes of phosphine. This article reviews the experimental and clinical features of AlP intoxication and tries to suggest a way to encounter its poisoning.

A systematic review of aluminium phosphide poisoning

Every year, about 300,000 people die because of pesticide poisoning worldwide. The most common pesticide agents are organophosphates and phosphides, aluminium phosphide (AlP) in particular. AlP is known as a suicide poison that can easily be bought and has no effective antidote. Its toxicity results from the release of phosphine gas as the tablet gets into contact with moisture. Phosphine gas primarily affects the heart, lungs, gastrointestinal tract, and kidneys. Poisoning signs and symptoms include nausea, vomiting, restlessness, abdominal pain, palpitation, refractory shock, cardiac arrhythmias, pulmonary oedema, dyspnoea, cyanosis, and sensory alterations. Diagnosis is based on clinical suspicion, positive silver nitrate paper test to phosphine, and gastric aspirate and viscera biochemistry. Treatment includes early gastric lavage with potassium permanganate or a combination with coconut oil and sodium bicarbonate, administration of charcoal, and palliative care. Specific therapy includes intravenous magnesium sulphate and oral coconut oil. Moreover, acidosis can be treated with early intravenous administration of sodium bicarbonate, cardiogenic shock with fluid, vasopresor, and refractory cardiogenic shock with intra-aortic baloon pump or digoxin. Trimetazidine may also have a useful role in the treatment, because it can stop ventricular ectopic beats and bigeminy and preserve oxidative metabolism. This article reviews the epidemiological, toxicological, and clinical/pathological aspects of AlP poisoning and its management.

Clinical Toxicology of Insecticides

Some insects compete for our food, some damage construction materials and some are important disease vectors in humans and animals. Hence, it is not surprising that chemicals (insecticides) have been developed that kill insects and other arthropods. More recently introduced insecticides, such as the neonicotinoids, have been produced with the intent that humans and animals will not be harmed by their appropriate use. This chapter reviews the clinical features and management of exposure to organophosphorus (OP) and carbamate insecticides, neonicotinoids, phosphides and pyrethroids. In the developing world where the ambient temperature is often high and personal protection equipment often not worn, poisoning particularly from OP and carbamate insecticides is common in an occupational setting, though more severe cases are due to deliberate ingestion of these pesticides. Both of these insecticides produce the cholinergic syndrome. The neonicotinoids, a major new class of insecticide, were introduced on the basis that they were highly specific for subtypes of nicotinic receptors that occur only in insect tissues. However, deliberate ingestion of substantial amounts of a neonicotinoid has resulted in features similar to those found in nicotine (and OP and carbamate) poisoning, though the solvent in some formulations may have contributed to their toxicity. Phosphides interact with moisture in air (or with water or acid) to liberate phosphine, which is the active pesticide. Inhalation of phosphine, however, is a much less frequent cause of human poisoning than ingestion of a metal phosphide, though the toxicity by the oral route is also due to phosphine liberated by contact of the phosphide with gut fluids. It is then absorbed through the alimentary mucosa and distributed to tissues where it depresses mitochondrial respiration by inhibiting cytochrome c oxidase and other enzymes. Dermal exposure to pyrethroids may result in paraesthesiae, but systemic toxicity usually only occurs after ingestion, when irritation of the gastrointestinal tract and CNS toxicity, predominantly coma and convulsions, result.

Managing aluminum phosphide poisonings

Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO(4), coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management.

Effect of sweet almond oil on survival rate and plasma cholinesterase activity of aluminum phosphide-intoxicated rats

Introduction: Aluminum phosphide (ALP), as an effective pesticide and a substance used for protecting rice during storage, has become one of the commonest causes of poisoning and even suicide in developing countries including Iran and India. The authors aimed to study the efficacy of sweet almond oil as an antidote in ALP toxicity. Methods: The present experimental study was conducted over 35 rats. The animals were divided into four groups: one group as the control group and three other groups which received ALP alone or ALP and sweet almond oil with different time intervals. In addition to estimating the survival rate of the animals, plasma cholinesterase activity as a possible factor affected in ALP poisoning was evaluated. Results: Treatment by intragastric irrigation of sweet almond oil resulted in significant reduction of mortality. Moreover, mean plasma cholinesterase levels were inhibited in groups receiving ALP. Conclusion: Oral sweet almond oil, if especially used immediately after poisoning with ALP, improves the survival rate.

Hyperglycemia in acute aluminum phosphide poisoning as a potential prognostic factor

Aluminum phosphide (AlP) is a solid fumigant widely used in Iran as a grain preservative. When reacted with water or acids, AIP produces phosphine gas, a mitochondrial poison that interferes with oxidative phosphorylation and protein synthesis. Poisoning by AIP is one of the most important causes of fatal chemical toxicity in Iran. There are few studies in the medical literature addressing prognostic factors associated with AlP poisoning. In this prospective study conducted across a 14-month period commencing on 21st March 2006, we enrolled all patients admitted to the ICU of Loghman-Hakim Hospital Poison Center (Tehran, Iran) with AIP poisoning, no history of diabetes mellitus diagnosed before hospitalization, and normal body mass index. We recorded patient-specific demographic information, blood glucose level on presentation (before treatment), arterial blood gas (ABG) analysis, time elapsed between ingestion and presentation, ingested dose, duration of intensive care admission, and outcome data related to each presentation. We enrolled the group of patients who survived the intoxication as a control group and compared their blood glucose levels with those who died because of AlP poisoning. Data were analyzed by Statistical Product and Service Solutions (SPSS) software (Version 12; Chicago, Ilinois, USA) using logistic regression, Pearson correlation coefficient and Student's t-test. P values of 0.05 or less were considered as the statistical significant levels. Forty-five patients (21 women and 24 men) with acute AlP poisoning were included in the study. The mean age was 27.3 +/- 11.5 years (range: 14-62 years). Thirteen patients survived (29%) and 32 expired (71%). AlP poisoning followed deliberate ingestion in all patients. The time elapsed between ingestion and arrival at the hospital was 3.2 +/- 0.4 h. There was no significant difference between survived and non-survived groups according to age, gender, and time to treatment. However, the difference between mean blood glucose levels in survived (143.4 +/- 13.7 mg/dL) and non-survived (222.6 +/- 20 mg/dL) cases was statistically significant (P = 0.021). There was no significant correlation between blood glucose level and time to treatment, age, gender, pH, HCO3 concentration, and ingested dose. Twenty-three (71.9%) of non-survived and four (30.8%) of survived patients had a blood glucose level greater than 140 mg/dL. After adjusting according to age, gender, ingested dose, pH and HCO3 concentration The odds ratio for hyperglycemia as a risk factor for death was 5.7 (CI of 1.4-23.4). In our study, patients who succumbed to AIP poisoning had significantly higher mean blood glucose levels than those who survived. This correlation of hyperglycemic effect and mortality suggests that it may be useful in guiding risk assessment and treatment of AIP poisoning. Management of hyperglycemia may have a useful role in treatment of these patients by allowing increased entrance of glucose into cells and reducing oxygen consumption.

Unintentional poisoning by phosphine released from aluminum phosphide

Aluminum phosphide as a releaser of phosphine gas is used as a grain preservative. In this case report, we describe an accidental severe poisoning in a 35-year-old woman, her 18-year-old daughter, and 6-year-old son caused by inhalation of phosphine gas released from 20 tablets of aluminum phosphide stored in 15 rice bags. The boy died 2 days after exposure before admission to hospital and any special treatment, but the others were admitted 48 h after exposure. They had signs and symptoms of severe toxicity, and their clinical course included metabolic acidosis, electrocardiographic changes, and hypotension. They were treated by intravenous administration of sodium bicarbonate, magnesium sulfate, and calcium gluconate. The patients were discharged after 3 days and followed up for 1 week after discharge. Rapid absorption of phosphine by inhalation, induction of hyperglycemia, and surviving of patients are interesting issues of this case report.

Aluminium phosphide poisoning

We describe a lethal poisoning in a healthy woman caused by deliberate ingestion of aluminium phosphide (AlP), a pesticide used to kill rodents and insects. Toxicity of AlP and review of cases reported to the National Poisons Information Service (London) 1997-2003 are discussed.