Impact of once-daily versus multiple-daily dosing of gentamicin on the incidence of acute kidney injury in patients treated with synergistic combinations of antibiotics.

Background: Gentamicin is a commonly used antibiotic with synergistic effects that is administered once or multiple times daily. However, the influence of the daily administration frequency on renal function has not yet been identified. This study aimed to investigate the effect of the daily dosing frequency on worsening renal function in patients receiving gentamicin.

Methods: This study included 35 patients undergoing gentamicin treatment who had at least one serum trough level measured and underwent therapeutic drug monitoring (TDM). We evaluated the influence of daily dosing frequency on gentamicin trough concentration and the risk of acute kidney injury (AKI).

Results: Compared to patients who received gentamicin once-daily dosing (n = 22), patients who received multiple-daily dosing (n = 13) had significantly higher initial and minimum trough concentrations after TDM. The proportion of patients with trough concentrations lower than 1.0 µg/mL was significantly higher in the once-daily dosing group at the initial trough concentration, whereas there was no significant difference at the minimum trough concentration after TDM. AKI developed in nine patients; however, there was no significant difference in the incidence of AKI according to the frequency of daily gentamicin dosing. In contrast, a higher minimum trough concentration after TDM was found to be a risk factor for AKI development with an odds ratio of 9.2 (95% confidence intervals; 1.3-65.5).

Conclusion: A higher trough concentration of gentamicin correlated with a higher incidence of AKI. The risk of developing AKI may be reduced by choosing a once-daily dosing regimen or implementing TDM.