Dried blood spots analysis with mass spectrometry: Potentials and pitfalls in therapeutic drug monitoring

• Dried blood spots are promising new samples for therapeutic drug monitoring.
• DBS assays require highly sensitive analytical methods, mainly mass spectrometric.
• Particular validation assays for DBS methods are described and discussed.
• Applications of DBS sampling for TDM in the last 10 years are reviewed.

Therapeutic drug monitoring (TDM) relays in the availability of specialized laboratory assays, usually available in reference centers that are not accessible to all patients. In this context, there is a growing interest in the use of dried blood spot (DBS) sampling, usually obtained from finger pricks, which allows simple and cost-effective logistics in many settings, particularly in Developing Countries. The use of DBS assays to estimate plasma concentrations is highly dependent on the hematocrit of the blood, as well as the particular characteristics of the measured analyte. DBS assays require specific validation assays, most of them are related to hematocrit effects. In the present manuscript, the application of mass spectrometric assays for determination of drugs for TDM purposes in the last ten years is reviewed, as well as the particular validation assays for new DBS methods.