Optimal Cefazolin Prophylactic Dosing for Bariatric Surgery: No Need for Higher Doses or Intraoperative Redosing.

PURPOSE: The goal of this pharmacokinetic (PK) study was to evaluate whether a single 2-g prophylactic dose of cefazolin given (IV) bolus provides effective protective cefazolin levels for prophylaxis against methicillin-sensitive S. aureus (MSSA), the primary skin pathogen in bariatric surgery.

MATERIALS AND METHODS: Thirty-seven patients having gastric bypass or sleeve gastrectomy received cefazolin 2-g preoperative prophylaxis. Serum, subcutaneous adipose tissue, and deep peri-gastric adipose tissue specimens were collected at incision and before skin closure. Cefazolin concentrations in serum and adipose tissue were determined by high-performance liquid chromatography.

RESULTS: Penetration of cefazolin, a water soluble antibiotic, into adipose tissue was only 6-8 % of simultaneous serum levels. However, cefazolin tissue concentrations in all adipose tissue specimens, exceeded mean MIC for MSSA.

CONCLUSIONS: Prophylactic cefazolin, given as a single 2 g (IV bolus 3-5 min before skin incision) was more than adequate in providing protective cefazolin levels for the duration of bariatric surgery. Cefazolin 2 g (IV dose bolus given just before skin incision) achieves protective adipose tissue levels (> MIC of MSSA) for the duration (usually < 4 h) of bariatric surgical procedures. In this study, cefazolin 2 g (IV bolus) provided protective adipose tissue levels for 4.8 h. Since cefazolin is a water soluble antibiotic (V d  = 0.2 L/Kg), penetration into adipose tissue is not V d not dose-dependent. Extremely high-dosed cefazolin, i.e., 3 or 4 g is excessive and unnecessary for bariatric surgery prophylaxis. A single cefazolin 2 g preoperative dose also eliminates the need for intraoperative redosing at 4 h.