Impact of pharmacist-led aminoglycoside stewardship: a 10-year observational study

Aminoglycosides are crucial for treating multidrug-resistant gram-negative infections and endocarditis. However, aminoglycosides are associated with significant risks of nephrotoxicity, necessitating careful dose selection and therapeutic drug monitoring. Therapeutic drug monitoring is essential for minimizing risk; however, few institutions routinely perform it. This study aimed to assess the impact of a pharmacist-driven therapeutic drug monitoring intervention on aminoglycoside usage trends and clinical outcomes.

This retrospective cohort study included 263 patients treated with aminoglycosides between 2014 and 2023. A pharmacist-led therapeutic drug monitoring intervention began in 2017, focusing on monitoring renal function, documenting patient weight, and closely managing aminoglycoside concentrations. Trends in aminoglycoside use and renal outcomes were analyzed.

Over the study period, appropriate use of aminoglycosides at the time of initial prescription increased from 49 to 82% (P < 0.01). Pharmacist dosing design at initial prescription increased significantly from 21% pre-intervention to 60% post-intervention (P < 0.01). The proportion of pharmacist intervention in initial dosing design increased over time. The proportion of patients with measured aminoglycoside blood concentrations significantly increased from 53% pre-intervention to 72% post-intervention (P < 0.01). The proportion of patients who were able to manage target blood concentrations from the initial aminoglycoside dose without dose adjustments increased from 31% pre-intervention to 42% post-intervention, although the results were not significantly different (P = 0.07). The incidence rate of renal impairment remained similar (11% vs. 12%; P = 0.85), although the annual average number of cases decreased from 4.3 before the intervention to 2.5 after. Similarly, there were no significant differences in clinical efficacy before and after the intervention (65% vs. 71%; P = 0.35). Furthermore, aminoglycoside stewardship led to a 56% cost saving.

Pharmacist-led aminoglycoside stewardship significantly improved the appropriate use of aminoglycosides and decreased the associated costs. Thus, pharmacist involvement is essential for the proper use of aminoglycosides. However, many patients required aminoglycoside dose reductions despite the pharmacist's guideline-based dosing design. Therefore, further accumulation of information on the management of aminoglycoside blood concentration may be necessary for the revision of these guidelines.