Simple approach to improving vancomycin dosing in intensive care: a standardised loading dose results in earlier therapeutic levels

Abstract

Patients in the Intensive Care Unit (ICU) often have sub-therapeutic vancomycin levels in the initial stages of therapy. Loading doses have been demonstrated to overcome this problem. The aim of this study was to determine the impact of a standardised loading dose and increased clinician awareness of under-dosing on the achievement of early therapeutic vancomycin trough concentrations in the ICU. A pre- and post-intervention observational study was conducted in the ICU following the introduction of a 2-g vancomycin loading dose and demonstration of local under-dosing. All initial vancomycin trough levels were examined, except those from neurosurgical patients. Primary outcome measures were the proportion of patients achieving therapeutic vancomycin levels and mean trough concentrations. A year after introduction, a review was conducted to further assess the impact and sustainability of the intervention. There were 31 courses of vancomycin in the pre-intervention period (no loading doses given) and 21 courses in the post-intervention period, of which 11 had a loading dose. In the pre-intervention group, 13% of courses achieved therapeutic concentrations. This increased to 33% in the post-intervention group (P= 0.08). A statistically significant increase in mean trough concentration, from 9.8 ± 6.6 mg/L to 14.9 ± 6.3 mg/L (P= 0.01), between the pre- and post-intervention groups was observed. During the follow-up period, results were similar to the post-intervention audit. A standardised loading dose is a simple and sustainable intervention that may improve early achievement of therapeutic vancomycin levels in critically ill patients. The clinical significance of this requires further study.