{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T13:56:13Z","timestamp":1791035773776,"version":"4.1.0"},"reference-count":40,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2025,3,27]],"date-time":"2025-03-27T00:00:00Z","timestamp":1743033600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2025,3,27]],"date-time":"2025-03-27T00:00:00Z","timestamp":1743033600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["ascpt.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Clinical Translational Sci"],"published-print":{"date-parts":[[2025,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Monitoring whole blood tacrolimus concentrations is standard in clinical practice; however, it may not fully reflect its therapeutic effects, as tacrolimus primarily acts within lymphocytes. While various intracellular quantification methods have been developed, many involve complex procedures such as evaporation, reconstitution, or specialized tools (e.g., magnetic beads, online solid\u2010phase extraction), limiting their accessibility. This study aimed to develop and validate a streamlined, sensitive method for measuring intracellular tacrolimus concentrations using 5\u00d710\n                    <jats:sup>5<\/jats:sup>\n                    peripheral blood mononuclear cells (PBMCs). Tacrolimus concentrations were quantified using liquid chromatography\u2010tandem mass spectrometry (LC\u2010MS\/MS). PBMCs were aliquoted into 50\u2009\u03bcL volumes containing 5\u00d710\n                    <jats:sup>5<\/jats:sup>\n                    cells and prepared via acetonitrile\u2010based protein precipitation. Chromatographic separation was performed using a Luna C18 column with a gradient mobile phase consisting of water with 20\u2009mM ammonium acetate, 0.1% formic acid, and methanol at a flow rate of 0.4\u2009mL\/min. The method demonstrated excellent linearity between 0.1 and 25\u2009ng\/mL, corresponding to intracellular concentrations of 1\u2013250\u2009pg\/5\u00d710\n                    <jats:sup>5<\/jats:sup>\n                    cells (\n                    <jats:italic>r<\/jats:italic>\n                    <jats:sup>2<\/jats:sup>\n                    \u2009=\u20090.999). Intra\u2010 and interday accuracy ranged from 98.1% to 109.8%, with precision between 2.08% and 8.70% across validation runs. Extraction recovery was high (93.0%\u201397.2%), with minimal matrix effects (100.9% at low QC and 111.6% at high QC). This validated LC\u2010MS\/MS method provides a rapid, reliable, and sensitive approach for pharmacokinetic studies and clinical applications, facilitating intracellular tacrolimus monitoring in transplant patients.\n                  <\/jats:p>","DOI":"10.1111\/cts.70210","type":"journal-article","created":{"date-parts":[[2025,3,30]],"date-time":"2025-03-30T04:35:31Z","timestamp":1743309331000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Robust\n                    <scp>UPLC<\/scp>\n                    \u2013\n                    <scp>MS<\/scp>\n                    \/\n                    <scp>MS<\/scp>\n                    Method With Acetonitrile for Precise Intracellular Quantification of Tacrolimus in\n                    <scp>PBMCs<\/scp>\n                    : A Step Toward Clinical Integration"],"prefix":"10.1111","volume":"18","author":[{"given":"Napatsanan","family":"Tanathitiphuwarat","sequence":"first","affiliation":[{"name":"Center of Excellence in Clinical Pharmacokinetics and Pharmacogenomics (PKPGx), Faculty of Medicine Chulalongkorn University  Bangkok Thailand"},{"name":"Pharmacogenomics Laboratory Center for Medical Diagnostic Laboratories, Faculty of Medicine, Chulalongkorn University  Bangkok Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5566-6403","authenticated-orcid":false,"given":"Asada","family":"Leelahavanichkul","sequence":"additional","affiliation":[{"name":"Center of Excellence on Translational Research in Inflammation and Immunology (CETRII), Department of Microbiology, Faculty of Medicine Chulalongkorn University  Bangkok Thailand"},{"name":"Immunology Unit, Department of Microbiology Chulalongkorn University  Bangkok Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1096-6020","authenticated-orcid":false,"given":"Pajaree","family":"Chariyavilaskul","sequence":"additional","affiliation":[{"name":"Center of Excellence in Clinical Pharmacokinetics and Pharmacogenomics (PKPGx), Faculty of Medicine Chulalongkorn University  Bangkok Thailand"},{"name":"Pharmacogenomics Laboratory Center for Medical Diagnostic Laboratories, Faculty of Medicine, Chulalongkorn University  Bangkok Thailand"},{"name":"Department of Pharmacology Faculty of Medicine, Chulalongkorn University  Bangkok Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4087-9032","authenticated-orcid":false,"given":"Suwasin","family":"Udomkarnjananun","sequence":"additional","affiliation":[{"name":"Center of Excellence on Translational Research in Inflammation and Immunology (CETRII), Department of Microbiology, Faculty of Medicine Chulalongkorn University  Bangkok Thailand"},{"name":"Division of Nephrology, Department of Medicine Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society  Bangkok Thailand"},{"name":"Excellence Center for Organ Transplantation (ECOT) King Chulalongkorn Memorial Hospital, Thai Red Cross Society  Bangkok Thailand"},{"name":"Renal Immunology and Transplantation Research Unit Faculty of Medicine, Chulalongkorn University  Bangkok Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,3,27]]},"reference":[{"key":"e_1_2_10_2_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1600-6143.2011.03686.x"},{"key":"e_1_2_10_3_1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa067411"},{"issue":"4","key":"e_1_2_10_4_1","article-title":"Tacrolimus Versus Cyclosporin as Primary Immunosuppression for Kidney Transplant Recipients","volume":"19","author":"Webster 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