Therapeutic drug monitoring of meropenem and piperacilin administered in continuous infusion. preliminary data

Methods Open, prospective, single-center study. All consecutive patients in whom treatment with MER or TZP was indicated from October 2014 to March 2015 were included. A 2g (MER) or 4g (TZP) loading dose was given followed by a 6g (MER) or 16-24g (TZP) continuous infusion over 24 hours. Serum concentrations were determined by high-performance liquid chromatography (HLPC) 1 hour, 24 hours and 3-5 days after the start of the infusion, determining maximum (Cmax) and free steady state concentrations (ƒCss). The objective was maintaining ƒCss 4-6 times above the MIC corresponding to the clinical breakpoint for Pseudomonas aeruginosa from our hospital database: 8 μg/ml for MER and 16/4 μg/ml for TZP. When the target was not achieved, the dose was adjusted. Results We enrolled 49 patients (73% male and 27% female) and determined 60 Css. Mean APACHE-II score was 16 ± 7. Empiric therapy was administered in 48 cases (80%). 13 patients (26%) were admitted to ICU after ≥ 7 days of hospitalization. 25 patients (51%) had septic shock, 2 (4%) severe sepsis and 1 (43%) sepsis. 1 patient (2%) had not systemic inflammatory response (SIR). 9 patients (18%) had bacteremia. We analyzed Css of MER/TZP during the first 24-48 hours, which are shown in Table1. Css determination led to the dose titration in 30% of the treatments.