Lecture 23 - Poisoning

Question 1

Pharamlogical toxicity due to extension of desired effect of warfarin, loop diuretics, insulin and AchE inhibitors

Answer 1

Warfarin: excessive bleeding
Loop diuretic: hypokalaemia, hyponatraemia, hypocalceamia
Insulin: hypoglycaemia
AchE: muscles weakness and SLUDGE

Question 2

Pharmological toxicity due to secondary effect of statins, thalidomide, Beta agonist and beta blockers

Answer 2

Statins - rhabdomyolysis
Thalidomide - birth limb defects
Beta blockers - bronchoconstriction
Beta agonists - increase HR

Question 3

Which effects are seen due to large doses and what drug causes it

Answer 3

Myocardial depression with large doses of beta blockers

Respiratory depression with large doses of opioid

Question 4

Pharmological toxicity due to overdose of theophylline and carbamazepine

Answer 4

Theophylline- convulsions and arrhythmia

Carbamazepine- respiratory depression

Question 5

Treatment of paracetamol overdose

Answer 5

N- Acetylcysteine - donates thiol groups so more glutathione can be available

Question 6

Adverse drug reactions of cyclophosphamide and how to treat it

Answer 6

Can cause haemorrhagic cystitis therefore give aggressive hydration and/ or Mesna

Question 7

Mesna

Answer 7

Increases the clearance of the toxic metabolic acrolein which protect the bladder

Question 8

Mechanisms to manage overdose

Answer 8

Immediate action
Supportive measures 
Enhance elimination 
Antidotes 
Prevention of absorption

Question 9

Immediate action

Answer 9

Stop patient from taking poison
Check vital signs and injury
History

Question 10

Supportive measures

Answer 10

Dependent on presentation:

• give oxygen
• manage electrolyte disturbance
• fluids

Question 11

Prevention of absorbtion

Answer 11

Activated charcoal - e.g. in paracetamol overdose but needs to be timed
Gastric lavage not recommended due to aspiration risk

Question 12

Elimination

Answer 12

Activated charcoal
Sodium bicarbonate- alkaline diuretics
Forced diuretics - not recommended
Haemodialysis - seriously ill patients

Question 13

Antidote types

Answer 13

Competitive inhibitors:

Cheating agents - treat cyanide, lead and iron poisoning

Manipulate drug metabolism

Antibodies and anti venom

Question 14

Competitive inhibitors

Answer 14

• Naloxone - opioid receptor antagonist

- atropine - organic phosphate

Question 15

Ethylene glycol (anti freeze poisoning)

Answer 15

Give fomepizole
Competes with aldehyde dehydrogenase
Prevents break down into toxic metabolites

Question 16

Digoxin specific antibody

Answer 16

Binds to digoxin to prevent action and increase clearance

Question 17

Drug review considerations

Answer 17

Drug interactions 
Contraindications 
Side effects 
Cost 
Appropriate medication right for patient 
Time limitation 
Adherence 
Lifestyle modification

Question 18

STOPP START

Answer 18

STOPP - screening tool of older people prescriptions

START - screening tool to alert tight treatment