Quantitative dried blood spot microsampling for therapeutic drug monitoring of -antiseizure medications by design of experiment and UHPLC-MS/MS

Background Therapeutic drug monitoring (TDM) of Antiseizure Medications (ASMs) is an essential tool for persons with epilepsy (PwE). Compared to traditional venipuncture, microsampling requires lower blood volume through less painful and invasive fingerprick offering a sampling methodology potentially performed at-home. This study aimed to validate the extraction method of ASMs from Capitainer®-qDBS microsampling. Five ASMs were considered. According to EMA guidelines, through technical and clinical validation, ASMs’ quantification from qDBS device was performed by UHPLC-MS/MS. Extraction parameters were optimized by Design of Experiment. Clinical validation was performed to compare ASMs concentrations in Capitainer®-qDBS with those in plasma in 30 PwE. Results The method used in the chosen extraction procedure was proven to be accurate and precise. Intra and inter-assay reproducibility analyses showed accuracy and precision ≤15 % across the calibration range. Recovery was >75 %, and matrix effect >75 %, for most of the ASMs analyzed. Stability was tested at 7, 15, and 30 days of storage, showing mutual robustness at 30 days at room temperature. No hematocrit effect was observed over a range of 20–70 %. Linear regression and Bland-Altman analysis indicated a good correlation for the ASMs considered. Significance A UHPLC-MS/MS assay was developed and validated according to EMA guidelines for quantifying ASMs from qDBS devices. This validation has the advantage of allowing the potential to utilize the new microsampling qDBS device, providing a patient-friendly approach to blood sampling eventually even at-home.