Population pharmacokinetics and target attainment of ciprofloxacin in critically ill patients.

PURPOSE

To develop and validate a population pharmacokinetic model of ciprofloxacin intravenously in critically ill patients, and determine target attainment to provide guidance for more effective regimens.

METHODS

Non-linear mixed-effects modelling was used for the model development and covariate analysis. Target attainment of an ƒAUC/MIC ≥ 100 for different MICs was calculated for standard dosing regimens. Monte Carlo simulations were performed to define the probability of target attainment (PTA) of several dosing regimens.

RESULTS

A total of 204 blood samples were collected from 42 ICU patients treated with ciprofloxacin 400-1200 mg/day, with median values for age of 66 years, APACHE II score of 22, BMI of 26 kg/m, and eGFR of 58.5 mL/min/1.73 m. The median ƒAUC and ƒC were 29.9 mg•h/L and 3.1 mg/L, respectively. Ciprofloxacin pharmacokinetics were best described by a two-compartment model. We did not find any significant covariate to add to the structural model. The proportion of patients achieving the target ƒAUC/MIC ≥ 100 were 61.9% and 16.7% with MICs of 0.25 and 0.5 mg/L, respectively. Results of the PTA simulations suggest that a dose of ≥ 1200 mg/day is needed to achieve sufficient ƒAUC/MIC ratios.

CONCLUSIONS

The model described the pharmacokinetics of ciprofloxacin in ICU patients adequately. No significant covariates were found and high inter-individual variability of ciprofloxacin pharmacokinetics in ICU patients was observed. The poor target attainment supports the use of higher doses such as 1200 mg/day in critically ill patients, while the variability of inter-individual pharmacokinetics parameters emphasizes the need for therapeutic drug monitoring to ensure optimal exposure.