Evaluation of cefotaxime concentrations in rat cerebral areas and serum by microbiological method and HPLC

The aim of the investigation was to verify the reliability and sensitivity of High Performance Liquid Chromatography (HPLC), compared to the classic microbiological method of plate diffusion, in evaluating cefotaxime concentrations in some cerebral areas and serum of the rat. The mean concentration of cefotaxime in the serum (after acute administration of 15 mg/kg i.m.) was 20 micrograms/ml with the microbiological method and 23 micrograms/ml with HPLC. No antibiotic was detectable, with both methods, in the cerebral areas. The results with both methods are in good accordance, although the HPLC technique is more sensitive and accurate.