Stability of a second-generation cephalosporin veterinary mastitis formulation after electron beam irradiation

Abstract

This study focused on the chemical stability of the cephalosporin (6R, 7R)-7-(1-pentafluorophenoxyacetamido)-3-[2-(5-methyl-1,3,4-thiodiazolyl)thiomethyl]-Delta(3)-cephem-4-carboxylic acid, sodium salt (cephem 1) formulation after electron beam (e-beam) irradiation. The cephem 1 concentrations of samples irradiated at 5, 10, and 15 kilograys for glass vials and low-density polyethylene (LDPE) cannula syringes were not statistically different from the concentrations of the nonirradiated control samples. Samples from each irradiation dose stored in controlled-temperature chambers at 5 degrees C and 30 degrees C for 24 months did not show any concentration changes within statistical limits compared with the nontreated samples. Samples from each irradiation dose stored at 40 degrees C for 12 months also did not show any concentration changes within statistical limits compared with the nontreated samples. The percentage of related substances increased slightly with the increase in e-beam irradiation level and storage temperature, but this increase was within the proposed label claim of 90% to 110% (45-55 mg/g). In conclusion, e-beam sterilization did not affect the chemical stability of cephem 1 intramammary formulation in LDPE cannula syringes, suggesting that e-beam irradiation may be a feasible method for terminal sterilization of this cephem 1 formulation.