lecture 13 - poisons and poisoning

Question 1

diagnosis from pupils

Answer 1

constricted

• opiates (morphine)
• clonidine
• anti-cholinesterases

dilated

• atropine
• tricyclic antidepressants
• MDMA

Question 2

diagnosis from skin

Answer 2

sweating

• increased = MDMA
• decreased = atropine

bullae (big blister)
- carbon monoxide

Question 3

diagnosis from odour

Answer 3

ethanol

garlic (arsenic, anti-cholinesterases)

almonds (cyanide)

Question 4

clinical chemistry diagnosis

Answer 4

in blood
(salicylate, paracetamol, ethanol, carbon monoxide, tricyclics, digoxin, theophylline)

in urine
(salicylate, opioids, tricyclics)

Question 5

general supportive treatment

Answer 5

airway
breathing
circulation

Question 6

Paracetamol hepatotoxicity

Answer 6

• metabolised by CYP2E1 to form NAPQI (causes liver damage)
• NAPQI inactivated by glutathione (limited reserves, used up by > 15g of paracetamol)
• treatment by N-acetyl-cysteine (precursor for glutathione)

• ethanol induces CYP2E1 (faster metabolism for paracetamol, however blocks enzyme when
alcohol present)

Question 7

treatment - decrease absorption

Answer 7

• emesis (inducing vomiting, can be done using syrup of ipecac)
• gastric lavage /stomach pump (must have reflexes, not for corrosives/hydrocarbons)
• activated charcoal (50g/ 4 hours) = binds drug
• for poisoning by paraquat (herbicide) = Fuller’s earth

Question 8

treatment - increase elimination

Answer 8

• activated charcoal (binds drug in gut to clear) = enteral dialysis
• haemo-perfusion = cannulation & passing blood over charcoal (theophylline), ion exchange
(aspirin) then back into body
• haemo-dialysis = dialysis machine for RF patients (effective for methanol, ethylene glycol)

Question 9

the antidote for methanol

Answer 9

ethanol

Question 10

the antidote for morphine

Answer 10

Naloxone

Question 11

the antidote for benzodiazepines

Answer 11

flumazenil

Question 12

the antidote for paracetamol

Answer 12

N-acetylcysteine