High Performance Liquid Chromatography–Tandem Mass Spectrometry Method for Simultaneous Quantification of Caspofungin, Anidulafungin and Micafungin in Human Plasma for Feasible Applications in Pediatric Haematology/Oncology

Abstract

A liquid chromatography–tandem mass spectrometry method was validated for the simultaneous quantification of anidulafungin (ANF), caspofungin (CSF) and micafungin (MCF) in human plasma. The triple quadrupole mass spectrometer was equipped with a heated-electrospray ionization probe and a Zorbax SB-C18 column. The calibration curves were generated using a weighted (1/x) linear regression for caspofungin, a weighted (1/x) quadratic function for micafungin and a log–log transformed linear regression for anidulafungin. The coefficients of variation of the normalized matrix factor were 11.2, 6.1 and 11.6% at low quality control level (QcL) and 11.5, 12.7 and 11.3% at high quality control level (QcH), for ANF, CSF and MCF, respectively, confirming the absence of matrix effects. The resulting method is sensitive (LLOQ 0.2 µg mL−1 for the echinocandins; LOD 0.05 µg mL−1 for MCF and 0.01 µg mL−1 for CSF and ANF), precise (within- and between-run from 2.9 to 15.0% and from 6.3 to 12.8%, respectively) and accurate (within- and between-run from 93.2 to 104% and from 95.9 to 109%, respectively) covering clinical concentration ranges acceptable for pediatric patients (0.2–10 µg mL−1). This analytical method could represent an efficient tool for monitoring the real-time efficacy and the safety of different recommended antifungal regimes in the pediatric population.