Therapeutic Drug Monitoring Flashcards
What is therapeutic drug monitoring?
TDM refers to the individualisation of drug dosage by maintaining blood drug concentrations within a targeted therapeutic window.
Therapeutic drug monitoring (TDM) involves the measurement of drug concentrations in a patients blood sample and the interpretation of these concentrations.
The goal is to individualise therapeutic regimens for optimal patient benefit and clinical outcome.
What are the aims of therapeutic drug monitoring?
To promote optimum drug treatment by maintaining blood drug concentration within a therapeutic range.
To aid the clinician in the choice of drug dosage in order to provide the optimum treatment for the patient and, in particular, to avoid toxicity.
What is the therapeutic window?
The concentration of drug in blood plasma where the drug has been shown to be efficacious without causing toxic effects in most people.
What are the indications for therapeutic drug monitoring?
To individualise pharmacotherapy - dosing.
To diagnose and avoid drug toxicity.
To assess adherence/compliance to pharmacotherapy.
To diagnose undertreatment and failed therapy.
To guide withdrawal of therapy.
To monitor and evaluate.
What information required to interpret a blood drug concentration?
Time blood sample collected.
Time dose given.
Dosage regimen (dose, duration, dosage form).
Patient demographics (age, gender, ethnicity).
Co-medications.
Relevant co-morbidities (e.g. renal/liver disease).
Indications for testing (e.g. toxicity, non-adherence).
What are the analytical methods for TDM assays?
Immunoassay.
High-performance liquid chromatography (HPLC).
Liquid chromatography – tandem mass spectrometry (LC-MS/MS).
Liquid chromatography – high resolution mass spectrometry (LC-HRMS).
Lithium.
what is the Interpretation blood drug conc if it is lower than anticipated?
Lower than anticipated • Patient nonadherent • Error in dosage regimen • Rapid elimination • Poor bioavailability • Drug-drug interaction Not achieved steady state
what is the interpretation blood con if it is higher than anticipated?
Higher than anticipated • Patient nonadherent • Error in dosage regimen • Slow elimination • Decreased renal/hepatic function • Drug-drug interaction • Time of sampling
