Applying Dried Blood Spots (DBS) techniques to pharmacokinetic analysis could significantly streamline the use of Therapeutic Drug Monitoring (TDM) in clinical practice. To establish DBS as a viable alternative sampling method, it is essential to demonstrate that results obtained from DBS analysis are reliable. This validation can be achieved through a cross-validation study. In this protocol, an original validated method, the plasma-based assay, serves as the "reference", while the alternative DBS-based analytical technique is the "comparator." The reliability will be defined analysing patients' samples with the new methods and comparing these results with those obtained with the reference LC-MS/MS methods (in plasma). The possibility to apply DBS technique to pharmacokinetic analysis should largely facilitate the application of TDM to clinical practice.
