Drug Overdose Flashcards
What is the most commonly used non-prescription analgesia?
Paracetamol
Frequently used for intentional overdose.
What are the types of paracetamol overdose?
- acute (ingested ≤ 1 hour)
- staggered (ingested >1 hour)
- therapeutic excess
What are early symptoms of paracetamol overdose occurring within 12 hours?
- asymptomatic
- nausea
- vomiting
- mild/moderate abdominal pain
What are late symptoms of paracetamol overdose occurring between 12-36 hours?
- severe abdominal pain
- metabolic acidosis
- jaundice
- acute kidney injury
- hepatic encephalopathy
- coma
- coagulopathy
What is the management for acute paracetamol overdose if presenting <8 hours after ingestion?
- Wait four hours from last ingestion → take blood sample
- Start acetylcysteine if 4hr paracetamol level above treatment line or evidence of liver damage
What should be done for acute paracetamol overdose if presenting 8-24 hours after ingestion?
- Blood samples immediately
- If ≥150mg/kg (or unknown amount) ingested or symptomatic, start acetylcysteine whilst awaiting results
- If <150mg/kg ingested, await bloods and treat if above treatment line or evidence of liver injury
How should staggered paracetamol overdose be managed?
- Start acetylcysteine treatment immediately
- Take bloods 4 hours after ingestion
- Consider discontinuing treatment if low risk hepatotoxicity:
- paracetamol concentration < 10mg/L
- normal ALT
- INR <1.3
- asymptomatic
What is the standard treatment regimen for paracetamol overdose?
- Standard 21-hour regimen
- Modified 12-hour SNAP regimen
What are the King’s College Criteria used for?
To identify which patients with hepatic failure should be referred for liver transplantation.
What is the most common salicylate?
Aspirin
What are the components of the management for salicylate toxicity?
- ABCDE
- Activated charcoal (if <1hr ingestion)
- IV fluids, potassium replacement & IV bicarbonate (urinary alkalinisation)
- Cooling measures (if hyperthermia), haemodialysis (for severe toxicity)
What is the difference between opiates and opioids?
- Opiates → natural alkaloids (e.g. morphine, codeine)
- Opioids → synthetic or semi-synthetic (e.g. fentanyl, oxycodone)
What are common clinical features of opioid overdose?
- Decreased consciousness
- Nausea and vomiting
- Respiratory depression
- Miosis (pinpoint pupils)
What should be done for the management of opioid overdose?
- Remove opioid source (if appropriate), ABCDE
- Naloxone (IV, IM, SC, intranasal), repeat doses if necessary
What effects do benzodiazepines have on GABA signalling?
Enhance GABA signalling → sedative, anxiolytic, anticonvulsant, muscle relaxant effects.
What are the clinical features of benzodiazepine overdose?
- Reduced consciousness (including coma)
- Respiratory depression
- Bradycardia
- Hypotension
- Rhabdomyolysis
- Hypothermia
What is the management approach for benzodiazepine overdose?
Most cases managed supportively; can use flumazenil to reduce seizure risk (in severe cases).
What are examples of tricyclic antidepressants?
- Amitriptyline
- Nortriptyline
- Dosulepin
What are the clinical features of tricyclic antidepressant overdose?
- Anticholinergic toxicity: dry mouth, confusion
- Na channel blockade: arrhythmias
- Severe effects: cardiovascular collapse, convulsions, coma
What is the management for tricyclic antidepressant overdose?
- No specific antidote.
- Activated charcoal (if <1hr after ingestion)
- IV sodium bicarbonate (reduce risk arrhythmias, acidosis)
- ABCDE resuscitation, intubation if needed
- Benzodiazepines for seizures
What is the management for warfarin overdose?
- Vitamin K
- Prothrombin complex
What is the management for heparin overdose?
Protamine sulphate
What is the management for beta-blocker overdose with bradycardia?
Atropine
What is the management for ethylene glycol poisoning?
- Fomepizole (inhibits alcohol dehydrogenase)
- Haemodialysis (in refractory cases)
What is the management for methanol poisoning?
- Fomepizole or ethanol
- Haemodialysis
What is the management for organophosphate insecticide poisoning?
- Atropine
- Pralidoxime
What are the clinical features of digoxin toxicity?
- Cardiac arrhythmias
- Bradycardia
- Nausea and vomiting
- Confusion
- Weakness
- Xanthopsia
- Blurred vision
What is the management for digoxin toxicity?
- Withhold digoxin
- Correct electrolytes
- Cardiac monitoring
- Digoxin-specific antibody fragments (fab fragments) (if severe arrhythmia, cardiac arrest or hyperkalaemia)
What is the management for iron overdose?
Desferrioxamine (a chelating agent)
What is the management for lead poisoning?
- Dimercaprol
- Calcium edetate
What is the management for carbon monoxide poisoning?
- 100% oxygen
- Hyperbaric oxygen
What is the management for cyanide poisoning?
- Hydroxocobalamin
- Combo: amyl nitrite, sodium nitrite, sodium thiosulfate
