Session 2_Introduction to therapeutic drug monitoring Flashcards
What is therapeutic drug monitoring (TDM)?
TDM involves tailoring a dose regimen to an individual patient by maintaining plasma or blood concentrations within a particular range (therapeutic range)
TDM is critical for optimizing drug therapy and minimizing toxicity.
What does the therapeutic range represent?
The range of drug concentrations within which the probability of a desired clinical response is high and the probability of unacceptable toxicity is low
It is essential for effective therapeutic drug monitoring.
Which pharmacokinetic parameters are relevant for dosage regimen?
- Bioavailability (F)
- Volume of distribution (Vd)
- Clearance (CL)
- Half-life (t1/2)
- Peak concentration (Css max)
- Trough concentration (Css min)
- Area under the curve (AUC)
These parameters help in designing effective dosage regimens.
What factors contribute to the success of drug therapy?
- Choice of the drug and drug product
- Design of the dosage regimen
Individual variation in pharmacokinetics and pharmacodynamics complicates dosage regimen design.
What are the basics of drug selection?
- Therapeutic consideration
- Cost
- Therapeutic equivalency
- Pharmacokinetic considerations
- Patient-specific information
- Medical history and pathophysiologic states
- Concurrent drug therapy and possible drug interactions
- Known allergies and drug sensitivities
These factors must be considered to ensure effective therapy.
What are patient factors that produce variability in drug response?
- Age
- Weight
- Pathophysiology
- Nutritional status
- Gender
- Lifestyle
- Genetic variability
These factors can significantly affect drug pharmacokinetics and dynamics.
What are drug factors that produce variability in drug response?
- Biopharmaceutics
- Pharmacokinetics
- Drug interactions
- Receptor sensitivity
Understanding these factors is key to optimizing drug therapy.
What does therapeutic drug monitoring (TDM) involve?
Measurement of drug concentrations in biological fluid and the interpretation of those concentrations
TDM is essential for clinical assessment of a drug’s pharmacokinetic properties.
What are indications for TDM?
- Individualizing therapy
- Toxicity assessment
- Diagnosing toxicity
- Avoiding toxicity
- Assessing adherence
- Diagnosing failed therapy
- Change in patient’s clinical state
- Monitoring drug interactions
- Guiding withdrawal of therapy
These indications highlight the importance of TDM in clinical practice.
Which drugs typically require therapeutic drug monitoring?
- Narrow therapeutic index (NTI) drugs
- Bronchodilators (e.g., Theophylline)
- Antibiotics (e.g., Aminoglycosides, Vancomycin)
- Immunosuppressants (e.g., Cyclosporine)
- Anticancers (e.g., Methotrexate)
- Cardiac drugs (e.g., Digoxin)
- Antiepileptics (e.g., Phenytoin)
Monitoring these drugs is crucial due to the risk of toxicity or therapeutic failure.
When should plasma sample timing for TDM be considered?
- When steady state (SS) is reached
- Earlier if toxicity is suspected
- At the appropriate time in relation to the last dose
Proper timing is critical for accurate drug concentration assessment.
What should be included in a therapeutic drug monitoring request?
- Time sample collected
- Time dose given
- Dosage regimen
- Patient demographics
- Co-medications
- Relevant co-morbidities
- Indications for testing
Detailed documentation ensures accurate interpretation of TDM results.
What are potential errors in interpreting TDM results?
- Assuming patient is at steady-state
- Assuming patient is adherent to therapy
- Not knowing the sampling time in relation to dose administration
- Not considering decreased renal/hepatic function
- Not considering drug interactions
- Using reference range as absolute values
Recognizing these errors is essential for accurate clinical decision-making.
What considerations are important before making dose adjustments?
- Correct timing of the sample
- Achievement of steady state
- Patient adherence to treatment
- Possible drug-drug interactions
- Liver/kidney dysfunction
These factors help ensure safe and effective dose adjustments.
What methods are available to individualize drug therapy?
- Clinical pharmacokinetic principles using simple mathematical relationships
- Computer programs covering more drugs
These tools assist in tailoring therapy to individual patient needs.
What is the conclusion regarding therapeutic drug monitoring?
- Knowledge of clinical pharmacokinetics is necessary for data interpretation
- Measurement of serum drug concentrations without appropriate interpretation is useless
- TDM is a complement to, not a substitute for, clinical judgment
- Successful TDM requires coordination among healthcare providers
A comprehensive approach is vital for effective therapeutic monitoring.
