Advances in LC-MS/MS methods and sample preparation strategies for therapeutic drug monitoring of immunosuppressive drugs

Abstract

Immunosuppressive drugs play a critical role in preventing organ rejection following transplantation and require close monitoring due to their narrow therapeutic ranges and interindividual pharmacokinetic variability. This review provides an overview of the pharmacokinetic properties, mechanisms of action, and clinical applications of drugs such as cyclosporine A, tacrolimus, sirolimus, everolimus, mycophenolate mofetil, and azathioprine. Within this clinical context, therapeutic drug monitoring (TDM) represents a cornerstone of individualized immunosuppressive therapy, directly linking drug exposure to efficacy and safety outcomes. Analytical approaches commonly used in the therapeutic monitoring of these agents-high-performance liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS)-are described, with particular emphasis on LC-MS/MS as the primary analytical platform due to its superior selectivity, sensitivity, and multianalyte capability. Recent advancements in sample preparation techniques are discussed in relation to their role in minimizing matrix effects and meeting the stringent analytical requirements of TDM. Tabulated data are presented on instrumentation, sample matrices, sample preparation techniques, calibration ranges, lower limits of quantification (LLOQ), analysis times, mobile phase compositions, and chromatographic columns for each analytical method. By critically integrating analytical methodology with clinical TDM needs, this review is intended to provide researchers and clinicians with a useful reference that supports the advancement of more effective and dependable strategies for therapeutic drug monitoring in clinical settings.