Pharmaceutica Analytica Acta

Abstract

Optimization of Microbiological Method by Turbidimetry for Quantification of Rifaximin Tablets: Validation, Application and Evaluation of Degraded Compounds

Kogawa AC and Salgadoa HRN

Rifaximin, an oral antibiotic, is used for the treatment of hepatic encephalopathy, ulcerative colitis, irritable bowel syndrome, Clostridium difficile, travelers' diarrhea and acute diarrhea. The development of methods which evaluate the potency of antimicrobials is fundamental. So, this work presents the validation of a microbiological method by turbidimetry to evaluate the power of rifaximin tablets, as well as the evaluation of degraded drug in acidic, basic, neutral and photolytic conditions. For this, Escherichia coli ATCC 10536 were used. The method was linear over the concentration range of 50-98 μg mL-1 with correlation coefficients 0.9976 (standard) and 0.9999 (sample), precise (repeatability RSD=4.96 and interday RSD=3.92), exact (recovery 100.70%); robust against small and deliberate variations in method and indicative of stability because it allowed evaluating rifaximin degraded under stress conditions. The results were compared with data obtained by high-performance liquid chromatography. The validated turbidimetric method is very useful to the routine quality control for microbiological evaluation of rifaximin tablets.