Increased 3-gram cefazolin dosing for cesarean delivery prophylaxis in obese women

• Published in: American journal of obstetrics and gynecology Vol. 213; no. 3; pp. 415.e1 - 415.e8
• Main Authors: Swank, Morgan L., Wing, Deborah A., Nicolau, David P., McNulty, Jennifer A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2015
• Subjects: Adult; Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - pharmacokinetics; Anti-Bacterial Agents - therapeutic use; Antibiotic Prophylaxis - methods; cefazolin; Cefazolin - administration & dosage; Cefazolin - pharmacokinetics; Cefazolin - therapeutic use; cesarean delivery; Cesarean Section; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Humans; Microbial Sensitivity Tests; minimal inhibitory concentration (MIC); Obesity; Obstetrics and Gynecology; Pregnancy; Pregnancy Complications; prophylaxis; Prospective Studies; Subcutaneous Fat - chemistry; Surgical Wound Infection - prevention & control; Treatment Outcome; minimal inhibitory concentration (MIC); cesarean delivery; cefazolin; prophylaxis; obesity
• ISSN: 0002-9378; 1097-6868; 1097-6868
• DOI: 10.1016/j.ajog.2015.05.030

The purpose of this study was to determine tissue concentrations of cefazolin after the administration of a 3-g prophylactic dose for cesarean delivery in obese women (body mass index [BMI] >30 kg/m2) and to compare these data with data for historic control subjects who received 2-g doses. Acceptable coverage was defined as the ability to reach the minimal inhibitory concentration (MIC) of 8 μg/mL for cefazolin. We conducted a 2-phase investigation. The current phase is a prospective cohort study of the effects of obesity on tissue concentrations after prophylactic 3-g cefazolin doses at the time of cesarean delivery. Concentration data after 3-g were compared with data for historic control subjects who had received 2-g. Three grams of parenteral cefazolin was given 30-60 minutes before skin incision. Adipose samples were collected at both skin incision and closure. Cefazolin concentrations were determined with the use of a validated high-performance liquid chromatography assay. Twenty-eight obese women were enrolled in the current study; 29 women were enrolled in the historic cohort. BMI had a proportionally inverse relationship on antibiotic concentrations. An increase of the cefazolin dose dampened this effect and improved the probability of reaching the recommended MIC of ≥8 μg/mL. Subjects with a BMI of 30-40 kg/m2 had a median concentration of 6.5 μg/g (interquartile range [IQR], 4.18–7.18) after receiving 2-g vs 22.4 μg/g (IQR, 20.29–34.36) after receiving 3-g. Women with a BMI of >40 kg/m2 had a median concentration of 4.7 μg/g (IQR, 3.11–4.97) and 9.6 μg/g (IQR, 7.62–15.82) after receiving 2- and 3-g, respectively. With 2 g of cefazolin, only 20% of the cohort with a BMI of 30-40 kg/m2 and none of the cohort with a BMI of >40 kg/m2 reached an MIC of ≥8 μg/mL. With 3-g, all women with a BMI of 30-40 kg/m2 reached target MIC values; 71% of the women with a BMI of >40 kg/m2 attained this cutoff. Higher adipose concentrations of cefazolin were observed after the administration of an increased prophylactic dose. This concentration-based pharmacology study supports the use of 3 g of cefazolin at the time of cesarean delivery in obese women. Normal and overweight women (BMI <30 kg/m2) reach adequate cefazolin concentrations with the standard 2-g dosing.