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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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