Evaluating the compatibility, stability, and antimicrobial effectiveness of vancomycin and cefepime admixtures in peritoneal dialysis solutions.

Peritoneal dialysis (PD) is a home-based option associated with peritonitis, a serious complication preferably treated with intraperitoneal (IP) antibiotics. Vancomycin and cefepime are commonly used empiric treatments, but data on their combined compatibility in PD solutions are limited. This study evaluated the in vitro physical compatibility, chemical stability, and antimicrobial activity of vancomycin (1-2 g) and cefepime (1 g) admixtures in Dianeal 2.5% and Extraneal 7.5% solutions. Admixtures were stored at 4 °C, 25 °C, and 37 °C for 168 h and assessed using visual inspection, optical density, pH, high-performance liquid chromatography, disk diffusion, and minimum inhibitory concentration testing. All admixtures remained physically compatible. At 4 °C, both antibiotics maintained  ≥ 90% of their initial concentration over 168 h. At 25 °C, vancomycin remained stable throughout, while cefepime's stability varied from 72 to 168 h in the two solutions. At 37 °C, vancomycin remained stable for 120-168 h, whereas cefepime was stable for 8-24 h. Antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa was preserved for 120 h across all conditions. These findings support the use of vancomycin-cefepime admixtures when refrigerated for up to 7 days, with cefepime remaining stable for 8-24 h at 37 °C, exceeding the minimum recommended intraperitoneal dwell time of 6 h.