Therapeutic Drug Monitoring (TDM)

Therapeutic Drug Monitoring (TDM) designates the clinical practice of measuring drug concentrations in blood or plasma to guide dosing decisions, ensuring exposures remain within therapeutic ranges that maximise efficacy while minimising toxicity. This approach proves particularly important for drugs with narrow therapeutic indices, significant interpatient variability, unpredictable pharmacokinetics, or concentration-response relationships that correlate strongly with clinical outcomes.

The pharmaceutical industry incorporates TDM considerations throughout development, particularly for therapies requiring individualised dosing strategies. Clinical trials evaluate concentration-effect and concentration-toxicity relationships supporting establishment of target ranges and monitoring recommendations. TDM applies widely to immunosuppressants like tacrolimus, antibiotics such as vancomycin, antiepileptics, and certain oncology agents, where inadequate exposure risks treatment failure while excessive exposure causes serious adverse effects. Implementation requires validated bioanalytical assays, standardised sampling timing, and clinical interpretation accounting for patient factors including renal function, liver function, age, and drug interactions. Regulatory submissions may include guidance on monitoring frequency, target concentrations, and dose adjustment algorithms. As personalised medicine expands and analytical technologies enable rapid, accurate measurement, TDM continues supporting safer, more effective treatment by optimising dosing based on measurable exposure.