LC-MS/MS method for simultaneous quantification of ten antibiotics in human plasma for routine therapeutic drug monitoring

Mirjana Radovanovic; Richard O Day; Graham D R Jones; Peter Galettis; Ross L G Norris

doi:10.1016/j.jmsacl.2022.11.001

LC-MS/MS method for simultaneous quantification of ten antibiotics in human plasma for routine therapeutic drug monitoring

J Mass Spectrom Adv Clin Lab. 2022 Nov 18:26:48-59. doi: 10.1016/j.jmsacl.2022.11.001. eCollection 2022 Nov.

Authors

Mirjana Radovanovic^{1

2}, Richard O Day^{1

3}, Graham D R Jones^{1

2}, Peter Galettis^{4

5}, Ross L G Norris^{1

2}

Affiliations

¹ St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia.
² SydPath, St Vincent's Hospital Sydney, Darlinghurst, NSW, Australia.
³ Department of Clinical Pharmacology & Toxicology, St Vincent's Hospital, Darlinghurst, NSW, Australia.
⁴ Centre for Drug Repurposing and Medicines Research, University of Newcastle, Callaghan, NSW, Australia.
⁵ Hunter Medical Research Institute, Kookaburra Circuit, New Lambton Heights, NSW, Australia.

Abstract

Background: Optimizing antimicrobial therapy to attain drug exposure that limits the emergence of resistance, effectively treats the infection, and reduces the risk of side effects is of a particular importance in critically ill patients, in whom normal functions are augmented or/and are infected with pathogens less sensitive to treatment. Achievement of these goals can be enhanced by therapeutic drug monitoring (TDM) for many antibiotics. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method is presented here for simultaneous quantification of ten antimicrobials: cefazolin (CZO), cefepime (CEP), cefotaxime (CTA), ceftazidime (CTZ), ciprofloxacin (CIP), flucloxacillin (FLU), linezolid (LIN), meropenem (MER), piperacillin (PIP) and tazobactam (TAZ) in human plasma.

Methods: Plasma samples were precipitated with acetonitrile and injected into the LC-MS/MS. Chromatographic separation was on a Waters Acquity BEH C₁₈ column. Compounds were eluted with water and acetonitrile containing 0.1 % formic acid, using a gradient (0.5-65 % B), in 3.8 min. The flow rate was 0.4 mL/min, and the run time was 5.8 min.

Results: The calibration curves were linear across the tested concentration ranges (0.5-250, CZO, CEP, CTA, CTZ and FLU; 0.2-100, MER and TAZ; 0.1-50, CIP and LIN and 1-500 mg/L, PIP). The intra and inter-day imprecision was < 11 %. Accuracy ranged from 95 to 114 %. CTZ and MER showed ionization suppression while CIP showed ionization enhancement, which was normalized with the use of the internal standard.

Conclusion: An LC-MS/MS method for simultaneous quantification of ten antimicrobials in human plasma was developed for routine TDM.

Keywords: Antimicrobials; CEP, cefepime; CIP, ciprofloxacin; CTA, cefotaxime; CTZ, ceftazidime; CV, coefficient of variation; CZO, cefazolin; ESI, electrospray ionization; FLU, flucloxacillin; HPLC, high performance liquid chromatography; ICU, intensive care unit; LC–MS/MS; LC–MS/MS, liquid chromatography tandem mass spectrometry; LIN, linezolid; LLOQ, lower limit of quantification; MER, meropenem; MIC, minimum inhibitory concentration; MRM, multiple reaction monitoring; NOR, norfloxacin; PIP, piperacillin; PK, pharmacokinetic; QC, quality control; R, resistant organism; RT, room temperature; Routine therapeutic drug monitoring; Rt, retention time; S, susceptible, wild type organism; SIL-IS, stable isotope labelled internal standard; TAZ, tazobactam; TDM, therapeutic drug monitoring; ULOQ, upper limit of quantitation; r2, coefficient of determination; β-Lactams.