Therapeutic Drug monitoring

Question 1

What does TDM involve

Answer 1

involves measuring drug concentrations in plasma, serum or blood
- this information is used to individualise dosage so that drug concentrations can be maintained within a target range

Question 2

when is TDM needed

Answer 2

1. monitoring compliance/adherence
2. individualise patient therapy
   - during early therapy
   - during dosages changes
3. suspected/avoiding toxicity
4. diagnosing under treatment
5. monitoring and detecting drug interactions
6. guiding withdrawal of therapy

Question 3

describe the process for reaching a dosage decision

Answer 3

1. a diagnosis is made
2. a drug is selected
3. dosage schedule is designed to reach a target plasma concentration
4. drug is administered
5. patient assessments are performed and drug concentrations are determined (TDM)
6. a pharmacokinetic model is applied and clinical judgement is used

Question 4

what is the process of TDM

Answer 4

1. sample collection
2. sample analysis:
   - chromatography
   - sensors and wearables
   - immunoassays
3. interpretation of results
4. medical judgement
5. adjustments of drug dosages
6. personalised dosage

Question 5

give examples of factors that influence TDM

Answer 5

1. Evidence- population variation, small sample sizes
2. analytical- method, manufacturer
3. pre analytical- collection timing, handling/processing
4. disease- genetic variation, co-morbidities
5. patient- age, renal function