Prophylactic cefazolin concentrations in morbidly obese patients undergoing sleeve gastrectomy: do we achieve targets?

Morbid obesity is known to increase the risk of surgical site infections. Optimal concentrations of prophylactic antibacterial drugs are required. Using Monte Carlo simulations, the aim of this work was to build a population pharmacokinetics model for a morbidly obese population to assess a 4000-mg dose of cefazolin recommended by the guidelines and to propose new administration schemes. One hundred and seventeen morbidly obese patients (mean body mass index, 46.95 kg/m(2)) received 40 0 0 mg of cefazolin intravenously before sleeve gastrectomy. Using population pharmacokinetics modelling and Monte Carlo simulations, probabilities of target attainment (PTAs) (subcutaneous tissue concentration of cefazolin above the minimum inhibitory concentration (MIC) throughout the surgical procedure was targeted) were determined. For Staphylococcus spp. and Streptococcus spp., which are the most frequent species isolated from post-surgical infections in bariatric surgery (MIC usually <= 2 mg/L), PTA remains greater than 0.9 until 2 h after administration of 40 0 0 mg of cefazolin. For MIC up to 4 mg/L, efficient prophylaxis was checked until 1 h after the initial administration. A 3000-mg regimen followed by a continuous infusion (10 0 0 mg/h) achieves these two targets until 4 h after the loading dose. A 2000-mg and a 3000-mg regimen do not achieve sufficient concentrations. According to the duration of surgery and MIC values, an initial administration of 40 0 0 mg should be sufficient, but for extended surgeries continuous infusion can be considered. (c) 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.