Personalized intensive care medicine : Implementation of therapeutic drug monitoring to assess antibiotic levels in intensive care patients

The intensive care unit at Asklepios Klinik Langen started a therapeutic drug monitoring (TDM) project in cooperation with the Aukamm pharmacy in Wiesbaden to measure antibiotic concentrations in the serum of intensive care patients for providing plasma level guided anti-infective therapy. The serum levels of the β‑lactam antibiotics meropenem, piperacillin, ceftriaxone and ceftazidime as well as the glycylcycline antibiotic tigecycline measured between January 1 and December 31, 2020, were evaluated retrospectively. Quantification by high performance liquid chromatography was carried out by the Aukamm pharmacy. During the observation period 288 serum level measurements were carried out in 131 patients with normal as well as impaired kidney or liver function, an increased volume of distribution as well as in patients with extracorporeal organ replacement therapies. The results of the most frequently measured antibiotic piperacillin/tazobactam showed a range of 1.95-308.50 µg/ml (median 76.54 µg/ml). The median serum level for meropenem was 26.46 µg/ml (0.75-157.36 µg/ml), for ceftriaxone 33.53 µg/ml (8.38-236.26 µg/ml) and for ceftazidime 158.56 µg/ml (24.09-204.61 µg/ml). The median trough level for tigecycline was 0.42 µg/ml (0.25-3.7 µg/ml) and therefore lower compared to administration via continuous infusion (median 0.88 µg/ml, 0.26-3.81 µg/ml). Therapeutic drug monitoring was successfully implemented in the intensive care unit of the Asklepios Klinik Langen. The serum level measurements showed considerable clinically relevant fluctuations in the antibiotic concentrations. Even an only rough approximation of effective antibiotic serum levels is not possible without TDM.