OSCE Stop - Monitoring Narrow TI Drugs

Question 1

What are the 2 main S/E of increased concentrations?

Answer 1

Ototoxicity

Renal failure

Question 2

What is the concentration profile for gentamicin?

Answer 2

high peak + low trough

Question 3

What is the post-dose level for gentamicin?

Answer 3

5-10mg/L

Question 4

What is the pre-dose level aim for gentamicin?

Answer 4

<1mg/L

Question 5

What is the main concern for vanc toxicity and how can this be avoided?

Answer 5

red man syndrome

Give infusion at rate of 10mg/min for doses over 500mg.

Question 6

What is the ideal trough vanc concentration?

Answer 6

10-20mg/L

Question 7

What 4 parameters should be monitored when using vancomycin IV?

Answer 7

blood counts
urinalysis
renal + liver function
auditory function

Question 8

What is the target INR for most indications?

Answer 8

2-3

Question 9

What are some signs of minor lithium toxicity?

Answer 9

Diarrhoea, vomiting
visual disturbance
muscle weakness

Question 10

What are 2 symptoms of serious lithium toxicity?

Answer 10

tremor

coma

Question 11

When should samples be taken for lithium?

Answer 11

12h post dose.

Question 12

What is the target concentration for lithium?

Answer 12

0.4-1 mmol/L

Question 13

What 3 body functions should be measured at baseline before starting lithium?

Answer 13

Renal
Cardiac
thyroid function

Question 14

What 3 additional factors should be measured before starting lithium?

Answer 14

BMI
Serum electrolytes
FBC

Question 15

Which 3 drugs/groups can cause increased lithium levels and how?

Answer 15

ACE-I
Diuretics
NSAIDS

Cause increased excretion of sodium and water = increased reabsorption of lithium (preferentially over sodium) = increase serum levels.

Question 16

What effect does increasing dietary sodium have on lithium levels?

Answer 16

Increased sodium = less reabsorption.

Since lithium binds preferentially than sodium - less lithium is reabsorbed also = reduced serum levels.

Question 17

Which 3 drugs/products can cause reduced serum lithium levels?

Answer 17

Theophylline
Caffeine
Acetazolamide

Question 18

What are the 3 types of toxicity from digoxin?

Answer 18

CNS - visual halos, green/yellow tinge.
GI - nausea, vomiting, diarrhoea.
Cardiac - arrhythmia

Question 19

When should digoxin concentrations be measured?

Answer 19

6h post dose.

Question 20

What are the 2 target concentrations for AF and HF?

Answer 20

AF = 0.5 - 2 mcg/L

HF = 0.5 - 1 mcg/L

Question 21

What are some signs of theophylline overdose?

Answer 21

vomiting
agitation + dilated pupils
arrhythmias
seizures

Question 22

What is the therapeutic target level for theophylline and when should a sample be taken?

Answer 22

10-20mg/L (sometimes 5-15mg/L is effective)

4-6h post dose.