Development and validation of an LC-MS/MS method for therapeutic drug monitoring in German clinical practice

Abstract

Therapeutic drug monitoring requires robust analytical methods capable of accurate quantification across diverse patient populations encountered in German clinical practice. This research describes the development and comprehensive validation of a liquid chromatography-tandem mass spectrometry method for quantifying therapeutic compounds in human plasma according to European Medicines Agency guidelines. The method was developed at the Institute of Clinical Chemistry, Charité Berlin, and validated across three German academic medical centers. The validated method demonstrated excellent linearity (R² = 0.9994) over the concentration range 0.5-1000 ng/mL with lower limit of quantification of 0.5 ng/mL. Intra-day and inter-day precision ranged from 2.9-7.8% and 3.8-9.2% coefficient of variation respectively, meeting acceptance criteria at all quality control levels. Accuracy ranged from 94.2% to 107.8% across the calibration range. Matrix effects were effectively compensated using stable isotope-labeled internal standards, with matrix factors of 0.97-1.02 in pathological samples. The method has been successfully implemented for routine therapeutic drug monitoring in participating German hospitals.