Stability of cefazolin sodium in four heparinized and non-heparinized dialysate solutions at 38 degrees C

Intraperitoneal administration of antibiotics is often required in the treatment of peritoneal dialysis-associated peritonitis. Extended use and heating may affect drug stability. The objective of our study was to determine the stability of cefazolin sodium (125 mg/L and 500 mg/L) in heparinized and non-heparinized dextrosecontaining peritoneal dialysis solution (Dianeal PD-2; Baxter Healthcare, Deerfield, Illinois, USA) containing 1.5%, 2.5%, or 4.25% dextrose, or 7.5% icodextrin, the new colloid formulation (Extraneal; Baxter), at 38 degrees C for 4 days.

Three poly-vinyl chloride containers of each dialysis fluid were stored at 38 degrees C for 4 days. Samples were taken after the bags were mixed and allowed to stand for 2 minutes. Two 500-microL samples were collected from each bag at hours 0, 12, 24, 36, 48, 60, 72, 84, and 96. Samples were then analyzed by high-performance liquid chromatography (HPLC) in our laboratory. In order to establish the stability-indicating nature of the method, drugs 1.0 mg/mL, vehicles, and their mixtures were subjected to a forced degradation. This is done by acid (2.0 mol/L HCl) and base (2.0 mol/L NaOH) hydrolysis, oxidation (H(2)O(2) 0.3%), and heat at 80 degrees C. Samples were analyzed every 30 minutes until approximately 25% of the drug's peak disappeared. The drug was considered stable if its concentration exceeded 90% of the original.

For all Dianeal PD-2 peritoneal dialysis solution containing 1.5%, 2.5%, and 4.25% dextrose, cefazolin sodium was considered stable at 38 degrees C for 60 hours at low cefazolin concentrations (125 mg/L), both with and without heparin, and for 48 hours at high cefazolin concentrations (500 mg/L). Cefazolin sodium was considered stable at 38 degrees C in icodextrin for 48 hours at low cefazolin concentrations in heparinized and non-heparinized solutions, and at high concentrations only in non-heparinized dialysate, not in heparinized dialysate. Cefazolin sodium was considered stable at 38 degrees C in icodextrin for 60 hours at high concentrations when heparinized.

Cefazolin sodium was stable in all four nonheparinized dialysate fluids for at least 48 hours at 38 degrees C. In heparinized icodextrin dialysate, high concentrations of cefazolin sodium were not stable for extended periods of time. Extended use and heating of dialysate containing cefazolin may adversely affect patient outcome.