Automated Extraction and Quantification of Immunosuppressants and Anticonvulsants from Dried Blood Spots: Evaluation of Transcend DBSA–TLX-1–MS/MS System

Immunosuppressants and anticonvulsant drugs are routinely quantified using liquid chromatography–tandem mass spectrometry (LC–MS/MS) in whole blood and serum, respectively, which necessitates frequent phlebotomy visits for patients. Alternatively, dried blood spots (DBS) measurements have the potential to reduce the cost of sample collection and shipping, while simultaneously enabling convenient at-home collection for patients. We evaluated Transcend™ DBSA–TLX-1–MS/MS System through method development and analytical validation for measurements of immunosuppressants (tacrolimus, sirolimus and everolimus) and anticonvulsants (levetiracetam and lamotrigine) in DBS. Given the relatively low analytical measurement interval (AMI) for these immunosuppressants, sufficient sensitivity is imperative, and the desired lower limit of quantitation (LLOQ) of 1 ng/mL was achieved, with an interday %CV less than 10% at the LLOQ. Conversely, the comparatively high AMI for the anticonvulsant drugs necessitated careful optimization to avoid saturation and minimize imprecision. For all analytes, carryover was minimal, and linearity and accuracy using spiked samples indicated adequate performance based on the regression comparisons. Therefore, our proof-of-concept study suggests that the DBSA–TLX-1–MS/MS has the potential to provide exceptional analytical performance, which will facilitate future clinical validations while minimizing labor required to perform DBS measurements.