Drug monitoring

Question 1

What is best for monitoring the benefits of furosemide?

Answer 1

Wt

Question 2

What is best for monitoring the adverse effects of furosemide?

Answer 2

U+Es

Question 3

Why is lithium monitoring important?

Answer 3

Due to narrow therapeutic range

Question 4

When are lithium levels measured post dose?

Answer 4

12 hrs post dose

Question 5

What is the aim for serum lithium levels?

Answer 5

0.4-1 mmol/L

Question 6

How often are lithium levels monitored?

Answer 6

1. Weekly after starting/dose change until stable
2. Every 3 months for 1 year
3. Every 6 months

Question 7

What serum lithium levels are toxic effects likely to manifest?

Answer 7

1.5 mmol/L

Question 8

What electrolyte imbalance can increase the risk of lithium toxicity?

Answer 8

Low sodium (pts are advised not to change dietary sodium intake)

Question 9

What advise is important for patients on methotrexate?

Answer 9

Report all symptoms of infection - especially sore throat

Question 10

What are the risks with methotrexate?

Answer 10

• Teratogenic (pregnancy test prior)
• Cirrhosis
• Blood disorders
• Renal excreted

Question 11

What is involved in methotrexate monitoring?

Answer 11

1. FBC/U+Es/LFTs every 1-2 weeks until therapy stabilised
2. Then every 2-3 months

Question 12

For patients on a multiple daily dose regime of gentamicin what should the peak and trough serum concentrations be? When do these change?

Answer 12

• One hour ‘peak’ concentration - 5-10 mg/L
• Pre-dose ‘trough’ concentration - 3-5 mg/L
• Lower concentrations in endocarditis

Question 13

When should gentamicin levels be monitored?

Answer 13

• After 3/4 doses
• After a dose change

Question 14

What is involved in clozapine monitoring?

Answer 14

FBC/WCC:
1. WCC weekly for 18 weeks
2. Fortnightly up to a year
3. Then monthly

Fasting blood glucose:
1. Baseline
2. At 1 month
3. Every 4-6 months

Question 15

When is CK measures in patients starting statins?

Answer 15

If have increased risk of myopathy/pre-existing muscle pain

Question 16

What is involved in statin monitoring?

Answer 16

• LFTS - baseline, 3 months, 12 months
• If ALT or AST is >3x the upper limit of normal then stop statins
• Statins are metabolised by the liver so hepatic impairment -> increased risk of myopathy

Question 17

What is a risk in patients on amiodarone?

Answer 17

• Pulmonary toxicity
• Gets CXR prior to starting treatment

Question 18

What requires monitoring in patients on amiodarone?

Answer 18

LFTs and TFTs every 6 months

Question 19

How often are TFTs required in patients on levothyroxine?

Answer 19

1. TSH every three months until stabilised (two similar measurements within the reference range, 3 months apart)
2. Yearly thereafter

Question 20

What requires monitoring in patients on carbimazole?

Answer 20

TFTs:
1. TSH every 6 weeks until within the desired range

Question 21

What electrolyte should you monitor in patients commenced on long term PPIs?

Answer 21

• Magnesium
• PPIs -> hypomagnesaemia
• Hypomagnesaemia can lead to an increased risk of arrhythmia and digoxin toxicity
• Especially important to check Mg if also prescribed digoxin

Question 22

What should be checked prior to starting sodium valproate?

Answer 22

• FBC
• LFTs

Question 23

What should patients on lithium have checked every 6 months?

Answer 23

• BMI - Li is associated with weight gain
• U+Es - Li is associated with electrolyte disturbances and renal impairment
• TFTs - Li can cause hypothyroidism

Question 24

What can be used to monitor the benefits of HF treatment (e.g. ACE-In)?

Answer 24

Exercise tolerance