Toxicology – Induction

Last Updated on by frcemuser

General Principle

  • Reduce absorption
    • Oral Adsorbents: activated charcoal
    • Gastric Lavage
    • Whole Bowel Irrigation
  • Increase elimination
  • Specific antidotes
  • Treat complications as required

Activated Charcoal

  • Give within 1 hour!
  • It May be effective after 1 hour for Tricyclics/opiates (delayed gastric emptying) , Salicylate (delayed absorption if enteric coated)
  • Disadvantages: Unpleasanttaste, may induce vomiting
  • Not effective for: Organophosphate/ Iron/ Lithium , Ethanol/ Methanol/ Ethylene Glycol

Gastric Lavage is Only used if:

  • Life-threatening overdose Patient presents early
  • method: large bore tube
  • Contra-indications: Corrosives/ petrol/ paraffin Unprotected airway

Active elimination

  • Urinary alkalinization
    • This enhances urinary excretion of weak acids (e.g aspirin, amitriptyline) by giving sodium bicarbonate infusion 1.5L of 1.26% over 2 hours.
  • Haemodialysis: Indications include (SLIME):
    • Salicylate
    • Lithium
    • Isopropanol
    • Methanol
    • Ethylene glycol
Drug Symptoms and signs
Paracetamol Frequently asymptomatic, nausea and vomiting (usually settle within 24 hours, if these continue, often with the development of right subcostal pain, this suggests the development of hepatic necrosis which may lead to encephalopathy, hypoglycaemia, haemorrhage, cerebral oedema and death)
Aspirin Hyperventilation, tinnitus, deafness, vasodilatation, sweating, coma
Tricyclic and related antidepressants Dry mouth, seizures, coma, cardiac conduction defects, arrhythmias, hypothermia, hypotension, hyperreflexia, respiratory failure, dilated pupils, urinary retention
Selective serotonin reuptake inhibitors (SSRIs) Nausea, vomiting, agitation, tremor, nystagmus, drowsiness, sinus tachycardia, seizures, serotonin syndrome (marked neuropsychiatric effects, autonomic instability and neuromuscular hyperactivity with hyperthermia, rhabdomyolysis, renal failure, coagulation deficiencies)
Beta-blockers Lightheadedness or syncope due to bradycardia and hypotension; heart failure can be exacerbated or precipitated; sotalol can cause ventricular tachycardia; propranolol can cause coma and convulsions
Calcium-channel blockers Nausea, vomiting, agitation, confusion, dizziness, coma, hyperglycaemia; dihydropyridine calcium-channel blockers cause profound peripheral vasodilatation and severe hypotension; verapamil and diltiazem can cause arrhythmias including complete heart block and asystole
Iron salts Nausea, vomiting, diarrhoea, abdominal pain, haematemesis, rectal bleeding, hypotension, hepatocellular necrosis, coma, shock
Lithium Initially apathy and restlessness followed by vomiting, diarrhoea, ataxia, tremor, weakness, dysarthria, muscle twitching; in severe poisoning: electrolyte imbalance, dehydration, convulsions, renal failure, hypotension, coma
Theophylline Severe vomiting, restlessness, agitation, dilated pupils, hyperglycaemia, tachycardia, hypokalaemia; more serious effects: haematemesis, seizures, arrhythmias (supraventricular and ventricular)
Benzodiazepines Drowsiness, dysarthria, ataxia, nystagmus, respiratory depression, coma
Antimalarials – quinine, chloroquine, hydroxychloroquine Rapid onset of life-threatening arrhythmias and intractable convulsions
Phenothiazines and related drugs Sinus tachycardia, arrhythmias, hypothermia, hypotension, reduced consciousness, respiratory depression, dystonic reactions (may be seen with therapeutic doses), seizures
Second-generation antipsychotic drugs Drowsiness, hypotension, extrapyramidal symptoms, convulsions, ECG abnormalities such as QT prolongation
Amphetamines Initially: excessive activity, wakefulness, hallucinations, paranoia and hypertension; later: convulsions, hyperthermia, exhaustion, coma
Cocaine Agitation, hypertension, tachycardia, dilated pupils, hallucinations, hyperthermia, hypertonia and hyperreflexia, cardiac effects such as chest pain, arrhythmias, myocardial infarction
Opioids Drowsiness, coma, respiratory depression, pinpoint pupils
Methylenedioxymethamphetamine (MDMA) Delirium, coma, hyperthermia, rhabdomyolysis, acute renal failure, acute hepatitis, disseminated intravascular coagulation, adult respiratory distress syndrome, hyperreflexia, hypotension, intracerebral haemorrhage, hyponatraemia, convulsions, ventricular arrhythmias

 

Toxidrome

Toxidrome Common Agents Signs and symptoms
Anticholinergic Antihistamines, tricyclic antidepressants, carbamazepine, phenothiazines Tachycardia, hyperthermia, dilated pupils, warm and dry skin, urinary retention, agitation
Cholinergic Carbamates, organophosphates insecticides, some mushrooms Salivation, lacrimation, urination, diarrhoea, bronchorrhoea, bronchospasm, bradycardia, vomiting
Hallucinogenic LSD, PCP, Magic Mushrooms Hallucinations, panic, seizures, hypertension, tachycardia, tachypnoea
Opiate Morphine, codeine, methadone Hypoventilation, hypotension, pinpoint pupils, sedation, bradycardia
Sedative/hypnotic Anticonvulsants, benzodiazepines, ethanol Ataxia, blurred vision, sedation, hallucinations, slurred speech, nystagmus
Sympathomimetic Amphetamines, cocaine, MDMA Tachycardia, hypertension, dilated pupils, agitation, seizures, hyperthermia, sweating

Antidotes

Antidote Poisoning
Acetylcysteine Paracetamol
Atropine Organophosphate insecticides, nerve gases
Calcium chloride/gluconate Calcium channel blockers
Calcium disodium EDTA Lead
Cyproheptadine (Periactin®) Serotonin syndrome
Dantrolene Neuroleptic malignant syndrome
Deferoxamine mesylate (Desferal®) Iron
Digoxin Immune FAB (Digibind®, DigiFab®) Digoxin
Flumazenil (Romazicon®) Benzodiazepines
Fomepizole (Antizol®) Ethylene glycol & methanol
Glucagon Beta blockers, calcium channel blockers, insulin
Hydroxocobalamin (Cyanokit®) Cyanide
Intravenous Lipid Emulsion (Intralipid™) Local anaesthetics
Idarucizumab (Praxbind®) Dabigatran
Methylene Blue Methaemoglobinaemia
Naloxone Opioids
Octreotide (Sandostatin®) Sulfonylureas
Physostigmine Anticholinergic syndrome
Phytonadione (Vitamin K1) Warfarin
Pralidoxime (2-PAM, Protopam®) Organophosphate insecticides, nerve gases
Protamine sulfate Heparin
Sodium Bicarbonate Salicylates, tricyclic antidepressants

High dose Insulin Euglycaemic Therapy

HIET is a relatively new treatment for cardiogenic shock secondary to Calcium Channel Blocker or Beta-Blocker overdose refractory to normal treatment. It involves giving really high doses of insulin (1unit / kg = 70 units in an average person!) as a bolus, followed by an infusion

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