Population pharmacokinetics and pharmacodynamics of cefazolin using total and unbound serum concentrations in patients with high body weight

Eun Kyoung Chung; S Christian Cheatham; Daniel P Healy; Andrea H Stock; Sara Utley; Maureen Campion; Timothy Murrey; Alicia M Gesenhues; Julia Jeffery; Michael B Kays

doi:10.1016/j.ijantimicag.2023.106751

Population pharmacokinetics and pharmacodynamics of cefazolin using total and unbound serum concentrations in patients with high body weight

Int J Antimicrob Agents. 2023 Apr;61(4):106751. doi: 10.1016/j.ijantimicag.2023.106751. Epub 2023 Feb 8.

Affiliations

¹ Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, South Korea; Department of Pharmacy, Kyung Hee University Hospital at Gandgong, Seoul, South Korea; Department of Regulatory Science, Graduate School, Kyung Hee University, Seoul, South Korea; Institute of Regulatory Innovation through Science, Kyung Hee University, Seoul, South Korea. Electronic address: cekchung@khu.ac.kr.
² Franciscan St. Francis Health, Department of Pharmacy, Indianapolis, IN, USA.
³ James L. Winkle College of Pharmacy, Division of Pharmacy Practice and Administrative Sciences, University of Cincinnati Academic Health Center, Cincinnati, OH, USA.
⁴ Purdue University College of Pharmacy, West Lafayette and Indianapolis, IN, USA.
⁵ Purdue University College of Pharmacy, West Lafayette and Indianapolis, IN, USA. Electronic address: kaysm@purdue.edu.

PMID: 36758780
DOI: 10.1016/j.ijantimicag.2023.106751

Abstract

The objective of this study was to evaluate the steady state pharmacokinetics and pharmacodynamics of cefazolin in patients with a high body weight. Cefazolin was administered by 0.5-h infusions to 11 patients with total body weight (TBW) ≥120 kg receiving 3 g q8h, and 12 patients with TBW <120 kg receiving 2 g q8h. Total and unbound serum concentration-time data obtained from serial blood samples were analysed simultaneously by population pharmacokinetic modelling using NONMEM. Probability of target attainment (PTA) was calculated for various dosing regimens through Monte Carlo simulations based on the cumulative percentage of the dosing interval that the unbound concentration exceeds the minimum inhibitory concentration (MIC) value for the pathogen at steady state (fT_MIC) ≥40%, ≥60% and 100%. A two-compartment model with non-linear protein binding and allometric scaling of the central volume of distribution using TBW best characterized both total and unbound concentration-time data. Unbound clearance was significantly associated with creatinine clearance, and maximum protein binding constant was significantly associated with serum albumin concentration and body mass index (P <0.05). Based on unbound concentration-time profiles, all simulated regimens achieved PTA >90% at MIC values ≤2 mg/L using fT_MIC ≥40%, at MIC values ≤1 mg/L using fT_MIC ≥60%, and at MIC values ≤0.5 mg/L using fT_MIC of 100%. At fT_MIC ≥60%, 0.5-h infusion of cefazolin 1 g q8h achieved PTA <90% at MIC values ≥2 mg/L in patients with TBW≥120 kg; however, prolonged-infusion and higher-dose regimens improved PTA to >90%. Overall, cefazolin pharmacokinetics are altered considerably in obese patients. Higher-dose and/or prolonged-infusion cefazolin regimens should be considered in patients with TBW ≥120 kg, particularly those with less-susceptible Gram-negative infections.

Keywords: Cefazolin; Infectious diseases; Monte Carlo simulation; NONMEM; Obesity; Population pharmacokinetics.

MeSH terms

Anti-Bacterial Agents*
Body Mass Index
Cefazolin*
Humans
Microbial Sensitivity Tests
Monte Carlo Method
Obesity

Substances

Cefazolin
Anti-Bacterial Agents