Background and Importance Obesity is a disease that influences numerous physiological processes. Currently there is little pharmacokinetic data in obese patients and extrapolated data from patients with normal weight are often used. In order to optimise the dosage of drugs in obese patients, it is necessary to design specific population models in this group of patients.

Aim and Objectives To analyse the differences in the pharmacokinetic parameters of amikacin in hospitalised patients based on body mass index (BMI).

Material and Methods Retrospective observational study in which patients treated with amikacin between January and August 2022 were analysed. The variables collected were: age, weight, height, sex, serum creatinine, dosage regimen and amikacin level.

Patients were classified according to their BMI: less than 30 Kg/m2 (non-obese) and greater than 30 Kg/m2 (obese). The mean and standard deviation of the volume of distribution (Vd) and clearance (Cl) of the two groups were calculated using a pharmacokinetic programme (MwPharm) based on a single compartment model.

Statistical analysis was performed using Student’s t-test for independent samples.

Based on the data collected, BMI and creatinine clearance (according to the Cockcroft-Gault equation) were calculated. Patients with a glomerular filtration rate of less than 30 mL/min were excluded.

Results 42 patients (52% women) with 156 levels of amikacin and a mean age of 69 ± 28 years were included. The distribution of patients according to BMI was: 59% normal weight and 41% obese.

The mean and standard deviation of Cl of obese patients and normal weight were 2.67 ± 1.41 L/h and 1.92 ± 1.04 L/h, respectively. P-value from t-test was 0.04 (p < 0.05) for Cl.

Vd data were 0.314 ± 0.068 L/Kg (obese) and 0.28 ± 0.034 L/h (normal weight). P-value was 0.648 (p>0.05) for Vd.

Conclusion and Relevance Statistically significant differences were found in Cl between both groups: in obese patients amikacin Cl was higher than in patients with normal weight.

No significant differences in Vd were found between the two study groups.

Future studies are needed to design population pharmacokinetic models of amikacin in obese patients.

Conflict of Interest No conflict of interest