Multiple-daily aminoglycoside dosing for synergistic therapy: plasma concentration monitoring in adults, children and neonates

Aminoglycoside area under the concentration–time curve (AUC) monitoring is not used for patients treated with multiple-daily dosing for synergistic therapy; instead, measure the trough (predose) plasma aminoglycoside concentration. For effective synergistic activity, most studies suggest that a detectable gentamicin plasma concentration throughout the dosing period is necessary; however, to minimise toxicity, the gentamicin trough plasma concentration should not exceed 1 mg/L. In patients with impaired kidney function, 12-hourly dosing may be necessary to ensure that the trough plasma concentration remains less than 1 mg/L.

In patients without kidney impairment or with stable kidney function, measure the trough plasma concentration at least twice weekly. In patients with rapidly or substantially changing kidney function, measure the trough plasma concentration more frequently (in some cases daily). If kidney function deteriorates substantially, consider stopping the aminoglycoside – seek expert advice.