TDM and Toxicology

Question 1

Drugs which require therapeutic drug monitoring (3 types)

Answer 1

Lithium

Antibiotics-vancomycin, aminoglycosides

Immunosuppressants: Cyclosporin, tacrolimus, mycophenolate

Question 2

Drugs that may require monitoring (recognise)

Answer 2

• Digoxin
• Theophylline
• Caffeine
• Anti-epileptics

Question 3

Why are most drugs not monitored? (recognise)

Answer 3

Can assess clinical effects instead

Absence of side effects

Drug lacks toxic effects

Plasma level may not correlate to clinical effect

Question 4

What is Lithium used to treat?

Answer 4

Bipolar disorders

Question 5

How is Lithium monitored?

Answer 5

Sodium (diabetes insipidus)
Renal function
Thyroid function

Question 6

Why are antibiotics measured?

Answer 6

Avoid renal/ear toxicity

Tailor dose to therapeutic effect

Often peak and trough levels are measured

Question 7

Initial assessment of poisoning

Answer 7

ABCDE

GCS
Respiratory effort, cyanosis?
Pulse and BP
Pupil size and reactivity
Neurology

Question 8

Common drugs in self harm

Answer 8

Benzos
Anti depressants
Paracetamol
Aspirin
Alcohol

Question 9

Poisons that require specific treatment

Answer 9

Lead
Iron
Methanol
Ethylene glycol

Question 10

What is the toxic metabolite of paracetamol? How is it inactivated by conjugation?

Answer 10

NAPQI: N acetyl p benzoquinonimine

Conjugated with GLUTHIONE

When gluthione is depleted, it causes liver cell necorsis

Question 11

Paracetamol poisoning presentation?

Answer 11

Typically asymptomatic

Liver failure can result in 72-96 hours

Question 12

Management of paracetamol poisoning?

Answer 12

Measure paracetamol levels at presentation and AFTER 4 HOURS to determine treatment

Antidote is acetylcysteine

Measure INR and Creatinine

Question 13

Within how many hours of presentation of paracetamol overdose should NAC be given?

Answer 13

Within 8 hours but 4 hrs after presentation

Question 14

Symptoms of aspirin toxicity

Answer 14

Vomiting, sweating, TINNITUS, BLURRED VISION

Early respiratory ALKALOSIS

Later metabolic acidosis

Renal failure

Question 15

Management of aspirin poisoning, mild and severe

Answer 15

Mild/moderate: Requires only rehydration with K supplements

Severe: Specific elimination therapy with:

1. Activated charcoal
2. ALKALINISATION, give bicarbs to keep pH over 7.5 and help aspirin be excreted in urine
3. Haemodialysis if severe

Question 16

Symptoms of ethanol overdose

Answer 16

Depressed consciousness

Hypoglycaemia

Question 17

Rx for ethanol overdose

Answer 17

Supportive:
Monitor
Fluids
GLucose

Question 18

Lead poisoning symptoms

Answer 18

Abd. pain, anaemia, neuropathy

Question 19

Rx for lead poisnoning

Answer 19

Remove source

Chelation therapy with Ca EDTA or penicillamine

Question 20

SYmptoms of iron poisoning

Answer 20

Can be accidental in children

Abd pain
Nausea
Hypotension
Hepatic injury

Question 21

Rx for iron poisoning

Answer 21

Measure iron levels

Give Desferrioxamine

Question 22

Poisonous metabolite of methanol?

Answer 22

Formate

Question 23

Poisonous metabolite of ethylene glycol?

Answer 23

Glycolate

Question 24

Management of methanol or ethylene glycol poisoning?

Answer 24

Can cause severe metabolic acidosis

Treat with:
Ethanol (blocks toxic pathway)
Haemodialysis