For selected agents, how does therapeutic drug monitoring relate to dosing in renal impairment?

• A. TDM is never helpful in renal impairment.
• B. For selected agents, therapeutic drug monitoring helps tailor dosing in renal impairment.
• C. TDM should replace clinical assessment entirely.
• D. TDM should be used only for pediatric patients.

Answer: (B)

In renal impairment, drug clearance changes, which can either reduce exposure enough to fail treatment or allow dangerous accumulation. Therapeutic drug monitoring uses measured drug levels to guide dosing so you hit a target exposure that balances efficacy and safety. For certain agents with narrow therapeutic windows or complex, kidney-dependent pharmacokinetics, this targeted approach is especially helpful. By adjusting the dose or dosing interval based on measured levels (for example, vancomycin troughs or AUC-guided dosing, and aminoglycoside troughs), you tailor therapy to the individual’s reduced kidney function. This is why therapeutic drug monitoring is used for selected agents to tailor dosing in renal impairment. It isn’t a universal replacement for clinical judgment, and it isn’t limited to children.