An In Vivo-In Vitro Study of Cefepime and Cefazolin Dialytic Clearance During High-Flux Hemodialysis

Study Objectives. To assess the influence of in vitro and in vivo hemodialysis with a new high‐flux dialyzer on the clearance of cefazolin and cefepime; to assess the correlation of in vivo dialytic clearance of these antibiotics with blood flow rate; and to assess the correlation between in vitro and in vivo dialytic clearances of these antibiotics. Design. Prospective, open‐label, dialysis clearance study. Setting. A tertiary‐care, university health science center. Patients. Five adults who received high‐flux hemodialysis 3 times/week. Intervention. For the in vivo experiment, patients received a single intravenous infusion of cefazolin 1 g and cefepime 1 g before dialysis and then underwent a modified hemodialysis session. For the in vitro experiment, a buffered simulated plasma water (SPW) solution containing cefazolin and cefepime was used. Hemodialysis for both experiments was performed with use of a new high‐flux polysulfone dialyzer. Measurements and Main Results. Cefazolin and cefepime dialytic clearances were determined at blood and/or SPW flow rates of 100, 200, 300, and 400 ml/minute after a 15‐minute equilibration period. The degree of correlation of in vitro and in vivo clearances with blood flow rate was determined. Cefepime dialytic clearance increased proportionally with blood flow rate (p