13 - Poisons and poisoning

Question 1

What is treatment of poisoning largely based on?

Answer 1

Enhancing the elimination and antidotes

Question 2

2 types of poisoning?

Answer 2

Acute overdose

Chronic exposure

Question 3

Main things to look at when diagnosing poisoning?

Answer 3

• history
• pupils
• skin
• odour
• blood
• urine

Question 4

History?

Answer 4

• patients rarely lie

- because of the types of poisons they often OD on (amnesics and sedatives) they may be unreliable

Question 5

Constricted pupils?

Answer 5

Opiates (morphine)

Anti-cholinesterases

Question 6

Dilated?

Answer 6

MDMA
Atropine
Tricyclic anti-depressants (amitriptyline - anti-cholinergic)

Question 7

Sweating?

Answer 7

Increased - ampethamine

Decreased - atropine

Question 8

Bullae?

Answer 8

Are large blisters

Caused by CO poisoning

Question 9

Odour?

Answer 9

• ethanol
• garlic
  > arsenic or organophosphates (anti-cholinesterases)
• almonds
  > cyanide

Question 10

Blood?

Answer 10

• salicylate
• paracetamol
• ethanol
• CO
• digoxin
• theophyline

Question 11

Urine?

Answer 11

• salicylate
• opiods (low conc in blood but conc in urine)
• tricyclics

Question 12

Treatment?

Answer 12

General supportive (Airway, Breathing, Circulation)
Decrease absorption
Increase elimination
Specific antidote

Question 13

4 Ways to decrease absorption?

Answer 13

1. Emesis (vomit)
2. Gastric lavage (stomach pump)
3. Activated charcoal
4. Fuller’s earth (used for paraquat - herbicide)

Question 14

Emesis

Answer 14

Syrup of ipecac

Question 15

Gastric lavage

Answer 15

stomach pump
must have reflexes
NOT for corrosives or hydrocarbons as can make worse

Question 16

Activated charcoal

Answer 16

Give 50 grams every 4 hours 
Binds drug (inactivate or bind the drug before it is absorbed)

Question 17

How to increase elimination?

Answer 17

• activated charcoal (binds drug in the gut to eliminate)
• haemoperfusion
• haemodialysis
• diuresis

Question 18

Activated charcoal to increase elimination?

Answer 18

Things absorbed across the gut wall to so by passive absorption. Will diffuse from the blood back into the gut and bind charcoal to increase elimination.
Also known as enteral dialysis

Question 19

Haemo-perfusion?

Answer 19

Cannulation of blood over CHARCOAL (theophylline) or ion exchange (aspirin) then back into the body. Is invasive

Question 20

Haemodialysis

Answer 20

Good to increase the elimination of small molecules such as methanol and ethylene glycol

Question 21

Diuresis?

Answer 21

Enhances urinary elimination i.e. salicylate from aspirin

Salicylate is an acid so give HCO3- to enhance the acid elimination

Question 22

Paracetomal overdose

Answer 22

N - acetylcysteine

Question 23

Morphine overdose

Answer 23

Naloxone

Question 24

Methanol overdose

Answer 24

Ethanol (competitive)

Question 25

Anti-cholinesterases overdose

Answer 25

Atropine and pralidoxime

Question 26

Paracetomol hepatotoxicity?

Answer 26

• minor metabolite is NAPQI usually inactivated by glutathione but these reserves are used up in OD.
• NAPQI causes liver damage
• ethanol induces the CYP2E1
• acetylcystiene binds NAPQI and increase glutathione levels