In a therapeutic drug monitoring program, which activity is typically performed?

• A. Measuring drug concentrations to optimize therapy
• B. Measuring patient satisfaction with a drug
• C. Estimating dosing using population averages without measurements
• D. Documenting only adverse events

Answer: (D)

In a therapeutic drug monitoring program, the central activity is measuring drug concentrations and using those data to tailor and optimize therapy for the individual patient. This approach is essential for drugs with narrow therapeutic windows or highly variable pharmacokinetics, where small changes in dose or timing can significantly impact effectiveness or risk of toxicity. By obtaining appropriate blood samples (often at a specific time after dosing, such as a trough level), comparing the measured concentration to a target range, and adjusting the dose or dosing interval, clinicians can keep therapy within the desired range and recheck levels as needed.

Measuring concentrations to guide therapy is what makes TDM distinct from other safety or pharmacovigilance tasks. Documenting adverse events, while important for patient safety, falls under safety monitoring rather than the optimization focus of TDM. Similarly, estimating dosing using population averages without measurements ignores individual variability, and measuring patient satisfaction deals with outcomes rather than drug optimization.