Utility of Oxidation-Reduction Reaction for Determination of Gemifloxacin Mesylate and Moxifloxacin HCl in Pure Form and in Pharmaceutical Formulations using N-Bromosuccinimide

Abstract

Three sensitive spectrophotometric methods are presented for the assay of gemifloxacin mesylate (GMF) and moxifloxacin HCl (MXF) in bulk drug and in pharmaceutical formulations using N-bromosuccinimide (NBS) and three dyes, methyl orange, amaranth and indigo carmine, as reagents. The methods involve the addition of a known excess of NBS to drug in acid medium, followed by determination of unreacted oxidant by reacting with a fixed amount of methyl orange and measuring the absorbance at 510 nm (method A), amaranth and measuring the absorbance at 528 nm (method B) or indigo carmine and measuring the absorbance at 610 nm (method C). In all methods, the amount of NBS reacted corresponds to the amount of drug and the measured absorbance is found to increase linearly with the concentration of drug which is corroborated by the correlation coefficients of 0.9992- 0.9998. The systems obey Beer’s law for 0.1-4.8 and 0.2-4.0 μg mL-1 for GMF and MXF, respectively. The limits of detection and quantification are also reported. Intra-day and inter-day precision and accuracy of the methods have been evaluated. The methods were successfully applied to the assay of GMF and MXF in tablet preparations and the results were statistically compared with those of the reference methods by applying Student’s t-test and F-test. No interference was observed from the common tablet excipients. The accuracy of the methods was further ascertained by performing recovery studies via standard-addition method.