Quantification of meropenem in human plasma by HILIC - tandem mass spectrometry.

Meropenem is a substance from the carbapenem class of antibiotics. It is widely used in intensive care units to treat a broad range of severe bacterial infections. In this critically ill patient group therapeutic drug monitoring (TDM) is highly advisable in order to avoid under- as well as over-dosing. Here, we describe a HILIC-MS/MS method for the quantification of meropenem in human plasma which is suitable for TDM. After simple protein precipitation, the polar analyte was chromatographically separated by the HILIC mechanism on a silica based stationary phase with polyethylenimide coating. The calibration was linear over the range of 1-50μg/ml. The stable isotope labelled internal standard led to matrix independency of the quantification and to very good precision (relative standard deviations less than 5%) and accuracy (deviations from the expected values less than 4%). A cross-validation with a validated and established HPLC-UV method confirmed the accuracy of the HILIC-MS/MS method in real patient samples.