20.500.12556/DiRROS-29036 Development, validation and application of the dried blood spot analysis method for the determination of Ustekinumab in patients with Inflammatory bowel disease Background: Ustekinumab (UST) is a monoclonal antibody (mAb) used in the treatment of inflammatory bowel disease (IBD). Elevated serum concentrations are typically associated with improved therapeutic outcomes, and therapeutic drug monitoring (TDM) is a useful tool for guiding mAbs treatment. This study aimed to develop a dried blood spot (DBS) method for TDM of UST in patients with IBD. Methods: The commercial enzyme-linked immunosorbent assay for plasma samples was optimized for DBS samples and subsequently validated according to international guidelines for classical and DBS-specific validation parameters. It was then applied to analyze serum and DBS samples obtained from venous and capillary blood of IBD patients undergoing UST therapy. Results: The method was linear (3–12 mg/L) with acceptable inter-day accuracy (90.1–106%) and precision (<12%). We confirmed that there was no hematocrit effect and that DBS samples were stable for one month under room conditions. A linear model was developed between venous DBS and serum UST concentrations, which showed no systemic bias, and 71% of the samples were within ±20% of the mean. In addition, a linear correlation between venous DBS and capillary DBS samples was established, showing no significant bias, with 84% of samples within ±20% of the mean. Finally, a novel strategy was developed to overcome the limitations of poor-quality samples (irregular shapes) based on area image analysis. Conclusions: The newly developed DBS method is the first to enable reliable measurement of UST in capillary blood, appropriate clinical interpretation of the measured concentrations, and remote monitoring of patients in the early phase of therapy. ustekinumab dried blood spots venous blood capillary blood validation inflammatory bowel disease ELISA ustekinumab posušene krvne kapljice venska kri kapilarna kri validacija vnetna črevesna bolezen true false true Angleški jezik Slovenski jezik Neznano 2026-04-17 15:02:38 2026-04-17 15:02:39 2026-04-18 03:52:07 0000-00-00 00:00:00 2025 0 0 Nasl. z nasl. zaslona; Opis vira z dne 28. 8. 2025; str. 1-16 iss. 9, [article] 1253 Vol. 18 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 615.2:616.34-002 1424-8247 10.3390/ph18091253 246860035 RAZ_Mingas_Panagiotis-Dimitrios_2025.pdf RAZ_Mingas_Panagiotis-Dimitrios_2025.pdf 1 06AFEB56D249D4E650FAAD9FCE082493 9f61535127c31e5dff7eae27c9294e774c2247963cebe69263db1cb10930841d d8ffd980-3a5d-11f1-a7d2-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43355 https://www.mdpi.com/1424-8247/18/9/1253 1 b7f263cd-3a5d-11f1-a7d2-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43354 Univerzitetni klinični center Ljubljana 0 0 0