Intraoperative serum and tissue activity of cefazolin and cefoxitin
J. T. DiPiro, J. J. Vallner, T. A. Bowden Jr, B. A. Clark and J. F. Sisley
We determined the intraoperative serum and wound-muscle concentrations of
cefazolin and cefoxitin in 40 patients who were undergoing
cholecystectomies. The study employed an open-label design in which all of
the patients randomly received cefazolin sodium (20 mg/kg) or cefoxitin
sodium (30 mg/kg) intravenously while the patient was in the ward ("on
call") or with the induction of anesthesia. Multiple blood and wound-muscle
samples were collected intraoperatively and assayed for their cephalosporin
concentrations. Considerable differences in intraoperative serum and tissue
concentrations between antibiotics were apparent; there were usually higher
levels of cefazolin. In all of the patients who received cefazolin sodium,
the antimicrobial was detectable in wound tissue at wound closure, while it
was detectable in 86% and 38% of patients who received cefoxitin sodium
with anesthesia and on call, respectively. Because cefoxitin has a much
shorter elimination half-life than cefazolin it seems prudent to administer
the agent as close to the start of the operation as possible, and
readminister the agent every two to three hours until the wound is closed.
For cefazolin, on-call administration appears to be acceptable, with
readministration not required for at least four hours.
