Poisoning

Question 1

What are the two non-selective toxic actions of chemicals

Answer 1

1. Local irritation-site of exposure, denaturing macromolecules causing injury
2. Strong alkali/acid

Question 2

What is a selective toxic action of the chemical?

Give 2 common examples.

Answer 2

Selective refers to interference with a specific biochemical pathway, therefore, chemical has to be absorbed and distributed to a specific pathway.

2 examples:
1. Rattex: interferes with Vit K pathway, essentially superwarfarin (lots of bleeding)

2. Paracetamol: depletion of glutathione results in accumulation of NAPQI (glutathione needed to conjugate NAPQI which is a toxic metabolite)

Question 3

List 3 methods of gastric decontamination

Answer 3

1. emesis/lavage
2. activated charcoal
3. whole bowel irrigation

Question 4

What is eye decontamination?

Answer 4

run normal water/saline into the eyes for 15-30min

Question 5

2 methods to stimulate emesis

Answer 5

Stimulation of pharynx

Ipecacuanha

Question 6

Contraindications to using emesis to eliminate a toxic substance

Answer 6

Impaired level of consciousness
Corrosive substances
Hydrocarbons
Risk of seizures

Question 7

2 instances where gastric lavage is useful

Answer 7

1. ingestion less than 1-2 hours previous

2. large amount of toxic solid substance

Question 8

Contraindications to gastric lavage

Answer 8

1. Hydrocarbons/corrosive substances

2. Risk of GI haemorrhage

Question 9

Instances where activated charcoal is useful

Answer 9

1. salicylates
2. barbiturates
3. digoxin
4. TCAs
5. paracetamol
6. Ingestion less than 2 hours (this can be lenient)

Question 10

When is Multi-Dose Activated Charcoal (MDAC) useful?

Answer 10

Severely poisoned patients
Sustained-release tablets
Enterohepatic cycling (estrogen, TCAs)
Drugs secreted into bile or intestine (digoxin)

Question 11

When is Activated Charcoal contraindicated?

Answer 11

1. substances that are not absorbed by the body eg.
Strong acids or alkalis
Iron salts
Lithium
Petroleum products 
Cyanide

Other contraindications include:
Endoscopy due
Antidote by mouth

Question 12

When is Whole Bowel Irrigation contraindicated?

Answer 12

1. Bowel obstruction
2. Compromised airway (giving lots of fluids can produce a gag reflex)
3. Ileus

Question 13

When is Whole Bowel Irrigation useful?

Answer 13

Iron overload, body packers

Question 14

What are the 3 ways of enhancing drug clearance?

Answer 14

Urinary alkalinisation
Haemodialysis
Charcoal haemoperfusion

Question 15

Urinary alkalinisation

Answer 15

Used in salicylate overdose
Increases elimination by maintaining urine pH > 7.5
IV administration of sodium bicarbonate
Needs high care facility -Monitor potassium

Question 16

Haemodialysis

Answer 16

Salicylates
lithium
methanol

Question 17

Charcoal haemoperfusion

Answer 17

Barbs
Theophylline
Carbamezapine

Question 18

Symptomatic care

Answer 18

Seizures eg cocaine
Hypoventilation eg opiates
Hypoglycaemia eg salicylates

Question 19

Hypotension treatment

Answer 19

fluids, vasopressors, inotropes

Question 20

Hypertension treatment

Answer 20

benzodiazepines, sodium nitroprusside

Question 21

Arrhythmia

Answer 21

Bradycardia, eg β-blockers: use atropine, pacing
Tachycardia, eg cocaine, stimulants: use benzodiazepines
Stable VT: eg TCAs: use sodium bicarbonate, lidocaine

Question 22

Antidote for Digoxin

Answer 22

Digoxin immune fab

Question 23

Antidote for Paracetamol

Answer 23

Acetylcysteine

Question 24

Antidote for Opioids

Answer 24

Naloxone

Question 25

Antidote for Benzos

Answer 25

Flumazenil

Question 26

Antidote for Iron

Answer 26

Deferoxamine