Thalidomide measurement in plasma and dried plasma spot by SPE combined with UHPLC-MS/MS for therapeutic drug monitoring: Supplementary files

Aims: To validate an SPE-ultra-HPLC-MS/MS method for thalidomide (THD) measurement in dried

plasma spot (DPS). Methods: Extraction included acetonitrile/water clean-up and online SPE. The

LOD, LLOQ, linearity, precision, accuracy, recovery, matrix effect, process efficiency, carryover, stability,

drug interference and dilution integrity were assessed. Results: The method was linear from 50 to

2000 ng/ml with a LOD of 20 ng/ml and LLOQ of 50 ng/ml. The coefficient of variation for precision

was 0.4–7.9% for intra-assay and 1.3–8.9% for interassay and accuracy was 81.4–97.1%. Adequate matrix

effect (100.6–107.0%), recovery (88.7–105.0%) and process efficiency (91.3–109.3%) were registered. DPS

was stable for 14 days at room temperature and 45◦C and for 4 months at -80◦C. The method was applied

to quantify THD in both wet plasma and DPS from patients with cutaneous lupus receiving THD treatment.

The difference between THD wet plasma and DPS concentration was <15%. Conclusion: The method is

suitable to quantify THD in DPS.