Simultaneous Determination of Ceftazidime and Avibactam in Human Plasma and Cerebrospinal Fluid by High-Performance Liquid Chromatography - Tandem Mass Spectrometry (HPLC-MS/MS)

A method is reported for the simultaneous determination of ceftazidime and avibactam in human plasma and cerebrospinal fluid utilizing high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS). The validated method was used to monitor the drugs in the treatment of central nervous system infections. The analytes were extracted from plasma and cerebrospinal fluid by simple protein precipitation using acetonitrile. A reversed-phase HSS T-3 column (5.0 mu m, 4.6 x 100 mm, Waters) was employed for the separation with a total analysis time of 5 minutes. Ceftazidime and avibactam eluted in 2.15 min and 2.87 min, respectively. The acquisition was separated into two periods to allow analysis in different ionization modes. A multi-reaction monitoring analysis was performed with the transition m/z 547.2-468.1 for ceftazidime, and m/z 552.3-468.1 for ceftazidime-d5 (positive mode), m/z 263.9-96.1 for avibactam, and m/z 136.8-92.8 for salicylic acid (negative mode). The plasma calibration curves of the analytes displayed good linearity across the range from 1 to 100 mu g/mL for ceftazidime and 0.1-20 mu g/mL for avibactam. Calibration curves for cerebrospinal fluid assay were established from 0.4 to 16 mu g/mL (ceftazidime) and 0.2-8 mu g/mL (avibactam). The accuracy was between 89.5% and 108.5%. The within- and between-batch precisions with the relative standard deviation were lower than 15%. The developed method had no observed matrix effects. The analytes were stable during the analytical and sample processing. The developed and validated method was successfully applied in routine clinical practice and helps to assess the adequacy of therapy and ensure sufficient ceftazidime and avibactam levels in central nervous system infections.