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Toxidromes

Essentials Anticholinergic (anti-muscarinic) toxic syndrome Anticholinergic toxic syndrome (ACTS) occurs as a result of the blockade of post-synaptic muscarinic receptors and/or a reduction or inhibition of cholinergic transmission at muscarinic receptor sites by drugs. Serotonin toxicity Clonus (spontaneous, inducible and ocular) can be diagnostic of serotonin toxicity (ST) once a serotonergic agent ingestion/toxicity has been identified. 1 The interaction of selective serotonin reuptake inhibitors (SSRIs) with…

Hymenoptera stings

Essentials 1 Hymenoptera strings are responsible for one or two deaths annually in Australia. 2 Hymenoptera venom is a common cause of allergy and anaphylaxis (∼3% of population). 3 Anaphylaxis is an absolute indication for venom immunotherapy. 4 Massive envenomation by bees and wasps can cause multi-organ involvement and death, although this is rare. 5 Mass envenomation does not appear to result from ant stings. Introduction…

Anticonvulsants

Essentials 1 Anticonvulsant overdose typically causes central nervous system effects, but other effects such as cardiotoxicity may be exhibited after the ingestion of certain agents. 2 Multiple doses of activated charcoal can reduce the duration of toxicity in carbamazepine and phenytoin toxicity. 3 Serum concentrations correlate with clinical toxicity in carbamazepine and phenytoin toxicity, guiding management in severe cases. 4 Depending on the agent, extracorporeal elimination…

Carbon monoxide

Essentials 1 Carbon monoxide is the commonest agent used in completed suicides by poisoning in Australia and the United Kingdom. 2 Carbon monoxide is produced by incomplete combustion and is found in car exhaust, faulty heaters, fires and in industrial settings. 3 Carbon monoxide poisoning may result in significant long-term neuropsychological sequelae. 4 Oxygen increases the elimination of carbon monoxide, and the extent of increase is…

Ethanol and other ‘toxic’ alcohols

Essentials 1 Ethanol is a major cause of morbidity, mortality and emergency department (ED) presentation in most Western societies. Presentations may result from acute intoxication, withdrawal or medical complications of chronic ethanol ingestion. 2 Ethanol causes central nervous system (CNS) depression that can be synergistic with other CNS depressants and can be life threatening without supportive care. 3 Ethanol withdrawal is commonly encountered in the ED…

Herbicides

Essentials 1 The mortality from acute paraquat poisoning is high owing to rapid multi-organ failure or delayed progressive pulmonary fibrosis. Ingestion of as little as one mouthful of 20% w/v solution is sufficient to cause death. No satisfactory treatment exists. 2 The toxic component of glyphosate-containing herbicides appears to be the surfactant co-formulant or its salt. The mechanism of toxicity is not confirmed, but severe poisoning…

Pesticides

Essentials 1 Acute pesticide poisoning is an important cause of morbidity and mortality worldwide, in particular in the Asia-Pacific region. 2 Existing systems for classifying the toxicity of pesticides are imperfect, whereby the toxicity of even ‘slightly hazardous’ pesticides is sometimes significant. Moderate-to-highly toxic pesticides may have a case-fatality rate of between 5% and 70% in patients with self-poisoning. 3 In addition to the pesticide constituent,…

Hydrofluoric acid

Essentials 1 Patients and medical staff are often unaware of the presence of hydrofluoric acid (HF) in household cleaning products. 2 Topical HF exposures may result in the gradual onset of severe local pain out of proportion to objective clinical signs. 3 Dermal exposures should be irrigated immediately and copiously. 4 Symptomatic dermal exposures should be treated with topical calcium. If pain persists, escalation to local…

Cyanide

Essentials 1 Cyanide is a metabolic poison associated with a high mortality. 2 Cyanide toxicity is characterized by rapid onset of central nervous, respiratory and cardiovascular effects and by metabolic acidosis. 3 Cyanide exposure correlates well with serum lactate levels. 4 Prompt resuscitative efforts with high-flow oxygen and administration of antidotes may be life saving; a number of alternative agents are available. 5 Cyanide poisoning from…

Drugs of abuse

Essentials 1 The diagnosis of intoxication with drugs of abuse is clinical. Good supportive care ensures optimal outcome in the majority of cases. 2 Predisposing factors for opioid-related deaths include co-ingestion of Central nervous system (CNS) depressant drugs, poor tolerance, high purity and reluctance to seek medical care. Naloxone is a useful adjunct in the management of airway and ventilation in opioid overdose. 3 Benzodiazepines are…

Iron

Essentials 1 Acute iron poisoning is a potentially life-threatening condition. 2 The risk of severe toxicity is determined by the dose of elemental iron ingested, not the weight of the iron salt. 3 Iron poisoning has both local (gastrointestinal) and systemic effects. 4 Early effective gastrointestinal decontamination with whole-bowel irrigation is important in the management of high-risk cases. 5 Chelation therapy with intravenous desferrioxamine is the…

Theophylline and caffeine

Essentials 1 Methylxanthine toxicity can be associated with life-threatening seizures and cardiac arrhythmias. 2 Predictors of toxicity include hypokalaemia, lactic acidosis and serum theophylline concentration. 3 Early identification of high-risk patients allows the institution of enhanced elimination techniques before life-threatening complications develop. Introduction Theophylline, a methylxanthine derivative related to caffeine, can result in potentially life-threatening overdose presentations to the emergency department (ED). The decline in theophylline…

Colchicine

Essentials 1 All deliberate self-poisonings with colchicine should be regarded as potentially life threatening. 2 Poisoning may present asymptomatically or with gastrointestinal symptoms only. 3 Consider the diagnosis in patients presenting with gastrointestinal symptoms followed by the development of multi-organ failure, especially bone marrow failure. 4 Key management points include early recognition of the potential severity of this poisoning, early gastrointestinal decontamination and aggressive supportive care.…

Antidiabetic drugs

Essentials 1 Deliberate self-poisoning with insulin or sulphonylureas may lead to life-threatening hypoglycaemia requiring prolonged observation and treatment over several days. 2 Octreotide blocks endogenous insulin secretion and is indicated in the management of symptomatic sulphonylurea toxicity. 3 Central venous access is often required following deliberate insulin overdose to facilitate treatment with concentrated glucose solutions. 4 Metformin is associated with life-threatening lactic acidosis. It does not…

Salicylate

Essentials 1 Salicylate pharmacokinetics become complex and alter markedly following overdose. 2 Treatment and disposition decisions are made on clinical signs, biochemistry and serum salicylate level trends. 3 The aim of therapy is to minimize metabolic and central nervous system toxicity. 4 Urinary alkalinization is an effective method of enhanced elimination after salicylate overdose. 5 Mechanical ventilation of patients with severe salicylate toxicity can worsen acidosis…

Paracetamol

Essentials 1 Paracetamol poisoning is one of the most common toxicological presentations to Australasian emergency departments. 2 The decision to treat patients with antidotal therapy following acute single ingestions should be made using the paracetamol treatment nomogram. 3 Acetylcysteine (NAC) prevents liver toxicity; however, this effect decreases with a delay to treatment. Patients presenting more than 8 hours post-ingestion should have NAC commenced while waiting for…

Lithium

Essentials 1 Chronic lithium toxicity is associated with significant morbidity and mortality, especially where diagnosis and treatment are delayed. a The diagnosis of lithium intoxication needs to be considered in any patient on lithium, and a serum lithium undertaken. b It usually develops due to impaired lithium excretion. The underlying factors must be identified and corrected. c It presents with neurological dysfunction. d Serum lithium levels…

Antidepressant drugs

Essentials 1 Tricyclic antidepressant (TCA) overdose is associated with severe cardiovascular toxicity, seizures, coma and death. 2 Sodium bicarbonate is the specific treatment of TCA cardiotoxicity. 3 Selective serotonin reuptake inhibitors (SSRIs) produce mild clinical effects in overdose; however very large ingestions or co-ingestion with another serotonergic agent can produce clinically significant serotonin toxicity. 4 SSRIs rarely produce cardiovascular toxicity; however, citalopram and escitalopram are associated…

Antipsychotic drugs

Essentials 1 Antipsychotics can cause numerous adverse effects at therapeutic doses, which may limit compliance. 2 Extrapyramidal effects are less pronounced with second-generation antipsychotics. 3 Clozapine is associated with agranulocytosis and myocarditis with therapeutic use and requires strict surveillance. 4 Following overdose, antipsychotics predominantly cause central nervous system (CNS) depression and cardiovascular effects. 5 Amisulpride can cause significant QT prolongation, potentially resulting in torsades de pointes.…

Cardiovascular drugs

Essentials 1 Calcium channel blockers, β-blockers, digoxin and sodium channel blocker poisonings are associated with potentially life-threatening toxicity. 2 The key to the management of calcium channel blocker and β-blocker toxicity rests with aggressive supportive care of the circulation including early use of hyperinsulinaemia euglycaemic therapy. 3 The onset of toxicity following overdose with slow-release formulations of calcium channel blockers may be delayed. 4 Early aggressive…