Background The recommended serum trough concentration of vancomycin is 15–20 mg/L.¹ Concentrations outside this interval increase the risk of adverse effects, therapeutic failure and resistance development. To achieve the target trough concentration more rapidly, it is recommended to start with a loading dose of 25–30 mg/kg in critically ill patients. Thereafter, the continuous dosing regimen is 1000 mg every 8th or 12th hour, but under severe infections a dose of 15–20 mg/kg every 8–12 hours can be considered.

Purpose To determine to what extent trough concentrations of vancomycin are within the recommended range, in patients in intensive care units (ICUs).

Material and methods A retrospective observational study was performed at Uppsala University Hospital, Sweden. Data on vancomycin dose regimen, treatment duration, serum concentration, type of infection and demographic information werer extracted from two electronic medical record systems: MetaVision and Cosmic. One-hundred and sixty-four patients treated with intravenous vancomycin at any of the four ICUs: Central Intensive Care Unit (CICU), Thorax Intensive Care Unit (TICU), Burn Injury Intensive Care Unit (BIICU) and Neurologic Intensive Care Unit (NICU) were included.

Results In total, 922 vancomycin concentrations were registered in 185 treatment episodes in 164 patients. More than half (54.7%) of all the trough concentrations were outside of target range, 21.8% were subtherapeutic and 32.9% supratherapeutic. A trend was seen that patients in the CICU and TICU more frequently had supratherapeutic concentrations and patients treated in the BIICU and NICU more often had subtherapeutic concentrations. Out of the 185 treatment episodes, 147 were initiated at an ICU and 61.2% of these started with a loading dose. A majority of cases (74%) had >1 trough concentration outside of target range and 55% of these non-therapeutic concentrations led to a change in dose regimen.

Conclusion More than half of the measured vancomycin concentrations were outside the recommended target range. Dosing and monitoring of vancomycin in patients treated in an ICU should be improved.

Reference and/or acknowledgements

1. Rybak M, et al. Therapeutic monitoring of vancomycin in adult patients: a consensus review of the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists. Am J Health Syst Pharm 2009;66:82–98.

Reference and/or acknowledgementsNo conflict of interest.