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NCT Number: NCT07253805

Plasma and Tissue Concentration of Cefazolin in Preoperative Prophylaxis in Patients Undergoing Bariatric Surgery

This study investigates whether current cefazolin dosing guidelines for obese patients-2 g IV for those <120 kg and 3 g IV for those ≥120 kg-achieve adequate plasma and tissue concentrations (≥8 mg/L) for effective surgical prophylaxis. While several retrospective and prospective studies suggest that a 2 g dose may be sufficient regardless of weight, findings are inconsistent and often rely solely on plasma concentrations. Given that tissue concentration at the site of action is a more relevant pharmacokinetic marker, the study emphasizes the need to measure cefazolin levels in adipose tissue. Previous research using microdialysis has shown reduced tissue distribution in obese patients, potentially warranting higher doses. The study also highlights variability in defining the minimum inhibitory concentration (MIC) required for prophylaxis, noting that 8 mg/L is often considered the threshold for Enterobacteriaceae. Ultimately, the study aims to clarify whether current dosing achieves effective antibiotic levels across different weight categories, with a focus on tissue concentrations.

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Key information

Conditions

Bariatric Sleeve Gastrectomy Cefazolin

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Institut universitaire de cardiologie et de pneumologie de Québec - Université Laval

Québec, Quebec, G1V 4G5, Canada

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Have a BMI ≥ 35 kg/m²
  • Undergo bariatric surgery (sleeve gastrectomy) via laparoscopy

Exclusion criteria

  • Under 18 years of age
  • Weight over 180 kg
  • Penicillin allergy
  • Pregnant or breastfeeding women
  • Chronic kidney disease (eGFR < 60 ml/min according to the Cockcroft-Gault equation)
  • Liver cirrhosis
  • Intraoperative blood loss ≥ 1 liter

Treatment and study plan

Primary outcomes

  1. Area Under the Concentration-Time Curve (AUC) of Cefazolin in Plasma, Adipose Tissue, and Dermal Tissue

    Time frame: During surgery

    AUC of cefazolin will be measured in plasma, adipose tissue, and dermal tissue at 0 minutes, 30 minutes, and at the end of surgery following administration according to current dosing guidelines.

    Unit of Measure:

    mg·min/L

Secondary outcomes

  1. Proportion of Patients Achieving Cefazolin Tissue Concentrations ≥ 8 mg/L

    Time frame: During surgery

    Proportion of patients with adipose and dermal tissue concentrations of cefazolin ≥ 8 mg/L at any time point (0 min, 30 min, end of surgery), based on the MIC for Enterobacteriaceae.

    Unit of Measure:

    Percentage of patients (%)

  2. Proportion of Patients Achieving Cefazolin Plasma Concentrations ≥ 2 mg/L

    Time frame: During surgery

    Proportion of patients with plasma concentrations of cefazolin ≥ 2 mg/L at each time point (0 min, 30 min, end of surgery), based on the MIC for methicillin-sensitive Staphylococcus aureus (MSSA).

    Unit of Measure:

    Percentage of patients (%)

  3. Comparison of Cefazolin Concentrations Across Weight Categories

    Time frame: During surgery

    Comparison of plasma and tissue concentrations of cefazolin across weight categories (<120 kg, 120-149 kg, ≥150 kg) to identify potential underexposure in higher weight groups.

    Unit of Measure:

    Mean concentration (mg/L)

  4. Tissue-to-Plasma Concentration Ratio of Cefazolin

    Time frame: During surgery

    Ratio of cefazolin concentration in tissue to plasma at each time point to assess distribution efficiency.

    Unit of Measure:

    Ratio (unitless)

  5. Time Above MIC (T>MIC) for Cefazolin in Plasma and Tissue

    Time frame: During surgery

    Duration (in minutes) that cefazolin concentrations remain above MIC in plasma and tissue compartments, if additional time points are available.

    Unit of Measure:

    Minutes

Other outcomes

  1. Screening and Eligibility Verification Through Demographic and Clinical Data

    Time frame: Preoperative period

    Participants will be evaluated during preoperative consultation by a bariatric surgeon. If eligible, informed consent will be obtained. Demographic and clinical data will be collected to confirm inclusion criteria:

    • Height (cm)
    • Weight at recruitment (kg)
    • BMI at recruitment (kg/m²)
    • Allergy status to penicillin

    Blood samples will confirm:

    • Absence of liver cirrhosis
    • Absence of chronic kidney disease (eGFR < 60 mL/min based on Cockcroft-Gault equation)

  2. Demographic Data Collected Before Surgery for Eligibility Assessment

    Time frame: preoperative period

    Prior to the start of surgery, demographic data will be collected to confirm participant eligibility according to inclusion criteria and establish baseline characteristics.

    Data collected:

    • Age (years)
    • Weight at admission (kg); will be used to determine the appropriate prophylactic dose of cefazolin.
    • Body Mass Index (BMI) at admission (kg/m²)

Sponsors and collaborators

Lead sponsor

Laval University

Other

Collaborators

  • Fondation IUCPQ

Registry information

Important dates

Study start
2019
Primary completion
2022
Study completion
2026
First posted
Nov 28, 2025
Registry last updated
Nov 28, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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