5PSQ-084 Adequacy of amikacin prescription in overweight and obese critically ill patients

<h3>Background and Importance</h3> Guidelines recommend an initial amikacin dose of 15–20 mg/kg/day, adjusted by ideal body weight (AiBW) for obese patients. However, these are often disregarded in clinical practice. <h3>Aim and Objectives</h3> This study evaluates the accuracy of the adjustments in amikacin first dose in overweight and obese patients from the Intensive Care Unit (ICU) and to determine the pharmacokinetics unit’s (PKU) effectiveness in achieving target therapeutic concentrations. <h3>Material and Methods</h3> Conducted at a tertiary hospital from January 2022 to August 2024, this retrospective study analysed initial amikacin prescriptions in ICU patients with a body mass index (BMI) over 25. Variables considered were sex, weight, height, dose administered (mg), serum concentration (mcg/ml) and the number of discrepancies between the dose recommended by Prioram guideline and the dose prescribed. The Devine formula was used to calculate AiBW. Optimal serum concentrations were defined as a trough level below 3 mcg/ml and a peak between 55 and 65 mcg/ml, according to Alvarez et al.¹ aminoglycoside monitoring standards. Data were obtained from electronic medical record system (Orion Clinic) and the pharmacokinetics lab (Gestlab). <h3>Results</h3> Thirty-eight overweight patients were included, being 63% (24) men, aged 61±13; and 37% (14) women, aged 74±10, with a mean BMI of 31.9±8.1 kg/m². A total of 102 amikacin concentration tests were done. Amikacin first dose was not adequate in 42% patients according to guidelines, resulting in 19% underdosed and 81% overdosed patients. Regarding pharmacokinetic recommendations, 79.4% were accepted. A total of 57.9% of patients continued amikacin treatment beyond the 5th dose, from which a 63.6% achieved optimal therapeutic concentrations. The inadequacy of the prescribed dose resulted in a 62.5% of patients who did not reach therapeutic concentrations after amikacin first dose, compared to 40.9% in those with a dosification according to guidelines. <h3>Conclusion and Relevance</h3> Despite guidelines, the amikacin first dose prescribed is often inadequate in overweight patients resulting in suboptimal serum concentration, exacerbated by patients’ critical conditions. This study highlights the PKU’s role in making recommendations to achieve therapeutic concentrations. <h3>References and/or Acknowledgements</h3> Alvarez F. <i>et al</i>. Recomendaciones para la monitorización de antibióticos en pacientes críticos ingresados en UCI. <i>Enfermedades infecciosas y Microbiología clínica</i>, 2008. <h3>Conflict of Interest</h3> No conflict of interest