Development and validation of a microbiological agar assay for determination of cefuroxime sodium in pharmaceutical preparations

Cefuroxime (CFU) is a semi-synthetic cephalosporin with a relatively broad-spectrum antimicrobial activity, and belongs to the second generation of cephalosporins. Regarding the quality control of medicines, a validated microbiological assay for determination of cefuroxime sodium in pharmaceutical formulations has not been reported yet. With this purpose, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method to quantify CFU sodium in injectable formulations. The assay is based on the inhibitory effect of CFU upon the strain of Staphylococcus aureus ATCC 6538P used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.9998) in the selected range of 8.0–32.0 μg/ml; precise [repeatability: relative standard deviation (RSD) = 1.56%; intermediate precision: between-day RSD = 1.27%; between analyst RSD = 1.13%] and accurate (101.58%). The bioassay specificity was studied by evaluation of degraded sample at 50 °C with analysis at 0, 24 and 48 h in parallel with the pharmacopeial liquid chromatography method for CFU. The results demonstrated the validity of the proposed bioassay, which allows reliable quantitation of CFU sodium in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine.