RESUMEN
BACKGROUND: Marbofloxacin (MAR) is an antimicrobial belonging to the fluoroquinolone class and is marketed in the form of tablets. There is no microbiological monograph in official compendia to evaluate the potency of the final product. Furthermore, the literature is scarce in this context. OBJECTIVE: The objective is to develop and validate a microbiological method by turbidimetry to evaluate the potency of MAR-based tablets, based on the principles of green analytical chemistry. METHODS: Purified water-ethanol (9 + 1, v/v) was used as diluent to prepare the MAR solutions at concentrations of 0.25, 0.8, and 2.56 µg/mL, brain heart infusion (BHI) broth as culture media, E. coli American Type Culture Collection (ATCC) 25922 at 10% and incubation in a shaker at 37°C for 4 h were used in the method. RESULTS: The method was: linear in the range of 0.25 to 2.56 µg/mL; selective against the sample adjuvants; precise (intra-day RSD 2.26%, inter-day RSD 3.49%, and inter-analyst RSD 3.59%); accurate with a recovery of 100.20%; and robust against changes in culture medium volume in the tube, shaker rotation, and incubation temperature in the shaker. The potency of MAR tablets was 96.98% using the proposed method. CONCLUSION: The turbidimetric method developed is a new, fast, and optimized option to the routine QC of MAR in tablets, since it allows the evaluation of the drug's potency in the final product and can be used to complement the results of the physicochemical analysis, in addition to being a green and sustainable alternative. HIGHLIGHTS: The work shows an ecological and green alternative to the routine microbiological pharmaceutical analysis of MAR tablets.