Timing of re-dosing based on population pharmacokinetic-pharmacodynamics target attainment analysis of cefmetazole in subjects undergoing lower gastrointestinal surgery

Abstract

Introduction: This study was conducted to evaluate the population pharmacokinetics of prophylactic cefmetazole sodium (CMZ) based on the serum concentrations and establish a pharmacodynamics target concentration exceeding the minimum inhibitory concentration (MIC) to design the re-dosing interval.

Methods: Serum (n = 362) samples from 107 individuals were analyzed using a nonlinear mixed-effects model. The pharmacodynamics index obtained was regarded as the probability of maintaining CMZ serum trough exceeding the minimal inhibitory concentration (MIC) of 2 mg/L. This MIC was chosen to account for methicillin-susceptible Staphylococcus aureus (MSSA), E. coli, and Klebsiella pneumoniae RESULTS: The final population pharmacokinetic model was a two-compartment model with linear elimination. Creatinine clearance and body weight were identified as significant covariates influencing the central clearance and volume of distribution in the central compartment. The probability of achieving serum concentrations exceeding the MIC₉₀ for MSSA, E. coli, and Klebsiella pneumoniae for a 1 g dose with a 10 min intravenous infusion was above 90% except for good renal function (CLcr ≧ 95 mL/min) at 2 h after the initial dose. For patients with good renal function (CLcr ≧ 95 mL/min), a CMZ of 2 g re-dosing interval seemed necessary to meet the achievement probability. In patients with impaired renal function (CLcr ≤20 mL/min), the probability of achievement exceeded 90% even when the dosing interval was extended to 8 h.

Conclusions: We evaluated re-dosing intervals based on the population pharmacokinetics. Re-dosing intervals should be determined based on renal function.

Keywords: Cefmetazole; Concentration; Population pharmacokinetics; Re-dosing.