Quantification of ceftriaxone sodium in pharmaceutical preparations by a new validated microbiological bioassay

Ceftriaxone is a broad spectrum antibiotic which belongs to the third generation of cephalosporin group. A simple, accurate, precise, reproducible and cost effective one level agar diffusion (5 + 1) bioassay was developed and validated for the estimation of potency and bioactivity of ceftriaxone sodium in pharmaceutical preparations. Among 15 strains of bacteria and 3 strains of fungi, Kocuria rhizophila ATCC-9341 was selected as the most effective organism against ceftriaxone sodium. Optimization of the bioassay was performed by investigating several factors such as buffer pH, inoculums concentration and standard solution concentration. The developed method was successfully validated with respect to linearity, precision and accuracy. The mean potency recovery value for ceftriaxone sodium in commercial dry powder injection of Monocef was 100.44%. An evaluated validation method showed linearity (r2 = 0.986), precision (interday R.S.D = 1.03%, between analyst R.S.D = 1.00%) and accuracy 101.17% (R.S.D = 0.80%). Identification of Monocef was performed by FTIR spectroscopy. The potency of the microbial bioassay was correlated with the HPLC method using the same commercial sample (Monocef). The obtained percent potency was 101.39% by the HPLC method. Results show that the bioassay can be applicable for quantitative determination of the potency with bioactivity in commercial formulations of ceftriaxone sodium.