Therapy drug monitoring of linezolid in serum of critically ill patients

OBJECTIVE: To investigate serum linezolid concentration in critically infectious patients in ICU. METHODS: Linezolid concentrations in serum were monitored in seven critical patients by HPLC. RESULTS: 34 linezolid serum samples were analyzed in critical patients, including 5 patients undergoing continuous venovenous haemofiltration (CVVH). Linezolid serum concentrations changed significantly in the seven patients during the treatment, with the average trough concentration range of 1.27-7.59 mg·L^-1. The minimum inhibitory concentration was 2 mg·L^-1. The linezolid trough concentration (1.27 mg·L^-1) in one patient was below the minimum inhibitory concentration, and another patient showed unexpected trough concentration fluctuation (nearly 10-fold). The clinical outcome of one patients, although his trough concentrations (7.59 mg·L^-1) were above minimum inhibitory concentrations, was failure. CONCLUSION: Linezolid serum concentrations in critically ill patients shows significant variability, and serum drug concentration should be monitored in these kinds patients in order to decide individual dosage regimen of linezolid in clinical practice.