Criteria for TDM
When considering whether a drug should be a candidate for TDM, there are several criteria that should be assessed. The most important can be summarized as to whether there is: - an available, validated assay to measure the drug concentrations or an other relevant biomarker
- a known relationship between the obtained concentration in plasma (or other relevant matrix) and the effect or toxicity of the drug
- variability in plasma concentration large enough that some of the obtained concentrations will be outside a presumed optimal range; i.e. whether it is a narrow index drug
- evidence supporting an increased probability of successful treatment -effect without toxicity- if dosing is adjusted to obtain a suggested target concentration range
- a need for lower or higher exposure in special subpopulations (e.g. transplant recipients with high risk)
- issues with respect to adherence to prescribed treatment (not relevant for drugs administered iv)
- ‘financial toxicity’; high prices may hamper availability of adequate treatment for patients, especially in lower economy regions. Personalized dosing can be used to explore whether lower doses or increased dose intervals can be effective, as has been demonstrated for immune checkpoint inhibitors in cancer treatment [1].