Drug Monitoring

Question 1

Before vancomycin therapy which parameter is important to measure?

Answer 1

Serum creatinine

Question 2

Before prescribing a station which of the following parameters is important to measure

Answer 2

Serum ALT

Metabolised by the liver, if raised more than 3x normal then contraindicated

Question 3

Monitoring lithium

Answer 3

• recommended lithium sampling is done 12 hours after last dose
• normal reference range for lithium is 0.4-0.8mmol/L
• routine serum lithium concentrations should be performed weekly after initiation and after each dose change, until concentrations are stable, and every 3 months thereafter
• sodium depletion is known to increase toxicity of lithium, advise patients not to alter diet

Question 4

Monitoring of methotrexate

Answer 4

• monitoring of FBC at regular intervals is imperative, but once therapy has been stabilised, full blood count can be monitoring every 2-3 months (risk of fatal blood duscrasias)
• MTX should not be started if LFTs are abnormal owing to risk of cirrhosis
• MTX is predominantly Renally excreted and toxicity is more likely in the presence of renal dysfunction

Question 5

Which important parameter is important to check and record before commencing therapy with olanzapine?

Answer 5

Fasting blood glucose -tested at baseline and regular intervals thereafter

(Diabetes and hyperglycaemia can occur in patients prescribed antipsychotic drugs)

Question 6

Which parameter is important to check while on an OCP

Answer 6

Blood pressure

Question 7

Monitoring of amiodarone

Answer 7

• baseline CXR before commencing treatment
• T3, T4 and TSH should be measure - increased risk of thyrotoxicosis
• LFTs for hepatotoxicity

Question 8

What should be checked first in a patient presenting with a sore throat who are prescribed carbimazole

Answer 8

• neutrophil count

(Sore throat may be an indication of infection, which could be due to carbimazole induced bone marrow suppression and thus agranulocytosis.)

Question 9

Commencing gentamicin therapy, what is important to measure?

Answer 9

For a multiple daily dose regimen, 1 hour peak serum concentrations should be between 3-5

-pre dose concentrations should be less than 1

Question 10

Before starting treatment, which of the following parameters should be measure on sodium valproate

Answer 10

ALT

Associated with hepatotoxicity and liver function

Question 11

Monitoring clozapine

Answer 11

• risk of fatal agranulocytosis, routine monitoring of FBC is required at regular intervals
• registration with a clozapine monitoring service is required