Lecture 13: Poisons and Poisonings

Question 1

Types of poisoning?

History taking?

Answer 1

acute overdose vs chronic exposure

patients rarely lie but can be unreliable if sedated or drug has an amnesic effect.

Question 2

changes to pupils?

Answer 2

Constricted

1. opiates (morphine)
2. clonidine (anti-hypertensive)
3. anti-cholinesterase

Dilated

1. atropine
2. tricyclic anti-depressants
3. amphetamine/MDMA

Question 3

Changes to skin?

Answer 3

Sweating

• increased = amphetamine/MDMA
• decreased = atropine

Bullae (large blisters)

• carbon monoxide (decreased O₂ to tissues)
• [barbituates]

Question 4

Odour?

Answer 4

Ethanol

garlic = arsenic

almonds = cyanide

Question 5

Clinical chemistry?

Answer 5

Blood chemisty (CO, ethanol, digoxin)

urine chemistry (tricyclics, opiates)

ECG changes

Question 6

Steps follows ABC (airways, breathing, circulation)?

Answer 6

Decrease absorption

increase elimination

give specific antidote if possible

Question 7

ways of decreasing absorption?

Answer 7

1. Emesis (syrup of ipecac)
2. gastric lavage (stomach pump)
3. acivated CHARCOAL (50g /4h ) - sticks and stops absorption

Question 8

Increased elimination?

Answer 8

1. Activated Charcoal (drugs go from blood to gut and back again but they bind to charcoal and so don’t go back)
2. Haemoperfusion - (charcoal for theophylline)
3. haemodialysis - (for methanol or ethylene glycol)
4. (Diuresis) - barely used

Question 9

Specific antidote?

Answer 9

N-acetylcysteine (paracetamol)

naloxone (morphine)-(diagnostic tool briefly wakes them up)

Flumazenil (benzodiazepines)

Ethanol (methanol)

Question 10

Stopping paracetamol hepatotoxicity

When to test levels?

Answer 10

CYP 2E1 creates minor metabolite NAPQI that is usually inactivated by Glutathione

Giving N-acetylcysteine supplies SH to make more glutathione that runs out during paracetamol overdose

for pills test at 4 hours and liquid at 2 hours due to decreased absorption time