Background and Importance Amikacin is a widely used antibiotic in neonates. An adequate dosing regimen is essential for effective and safe therapy; however, many patients do not achieve adequate plasma concentrations due to high interindividual variability in this population.

Aim and Objectives To compare the amikacin plasma concentrations in neonates according to the administered 15mg/kg/24h dosing regimen (15-DR), a previously established protocol, versus the amikacin 12mg/kg/24h (12-DR) new protocol, with the aim of establishing best initial dosing regimen (DR) that guarantees an effective and safe treatment, as well as analysing differences between subpopulations (preterm or term).

Retrospective observational study All patients admitted to neonatal unit or neonatal intensive care unit under amikacin treatment and with 12-DR or 15-DR between January-July 2023 were included. Patients with different DR were excluded.

The following variables were collected from the patients’ clinical histories (Orion Clínic®): gender, age, weight, preterm (<37 gestation weeks)/term, DR, minimum (Cmin) and maximum (Cmax) plasma concentrations. The optimal levels established were: Cmin <5 µg/mL and Cmax 20–30µg/mL.

Quantitative variables are expressed as mean and standard deviation (SD) and qualitative variables as number and percentage (%). The Chi-square test was used to compare qualitative variables. Statistical significance was considered when p ≤ 0.05. Statistical analysis was performed with SPSS version 23.0.

Results A total of 88 patients were identified, 11 were excluded because they were not neonates and 27 patients because they presented a different DR. Finally, 50 patients were included, 26 (52.0%) were male, mean age at level time was 7.6 (1.7) days, weight 2.9 (1.0) kg, and 35 (70.0%) were at term.

Regarding treatment, 24 (48.0%) patients were treated with 12-DR and 26 (52.0%) with 15-DR. The mean Cmin was 1.4 (0.2) µg/mL and 2.3 (0.3), respectively, and mean Cmax was 26.0 (0.9) µg/mL for 12-DR group and 33.5 (1.3) µg/mL for 15-DR group. A total of 18 (75.0%) patients with 12-DR achieved target plasma concentrations compared to 7 (26.9%) in the 15-DR group, statistically significant differences were observed. When comparing between premature and term patients, no statistically significant differences were observed.

Conclusion and Relevance This study demonstrates that amikacin 12mg/kg/24h dosing regimen guarantees better results in terms of optimal plasma concentrations in neonatal patients, which allows us to establish this dosage regimen as the initial dose in our patients. Clinical pharmacokinetics is essential for improving outcomes in neonates.

Conflict of Interest No conflict of interest.