Abstract: Four new spectrophotometric methods for the determination of gemifloxacin mesylate (GFX) have been proposed. The first three methods. i.e. A, B and C, are based on the oxidation of the drug with Fe (III) and the estimation of Fe (II) produced after chelation with either 1,10-phenanthroline or 2,2'-bipyridyl or ferricyanide at 515, 520 and 760 nm, respectively. The beer's law was obeyed in the concentration ranges of 3-15, 4-20 and 2-10 µg ml-1 with molar absorptivity of 3.55 x 104, 2.10 x 104 and 3.10 x 104 L mole-1 cm-1for methods A, B and C respectively. The fourth method, i.e. D was based on the interaction of GFX with ammonium heptamolybdate tetra hydrate, which resulted in the formation of molybdenum blue with λmax 825 nm. The linear dynamic range and the molar absorptivity values were found to be 6-30 µg ml-1 and 1.38 x 103 L mole-1 cm-1, respectively. The results of the proposed methods were validated statistically and are found to be accurate and precise. The proposed methods were applied successfully to the determination of GFX in commercial tablets.
Introduction: Gemifloxacin,(R,S)-7-(3-aminomethyl-4-syn-methoxyimino-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine -3-carboxylic acid methanesulfonate, is a new fluoroquinolone antibacterial compound with enhanced affinity for bacterial topoisomerase IV and is being developed for the treatment of respiratory and urinary tract infections. The compound has a broad spectrum of activity against Gram-positive and Gram-negative bacteria. Literature survey revealed that few analytical methods have been reported for the estimation of GFX; they include high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS), microchip electrophoresis, chiral high-performance liquid chromatography and chiral counter-current chromatography. To the best of our knowledge, there is no work in the literature reported about the spectrophotometric method for the analysis of GFX in either biological fluids or pharmaceutical formulations. Hence the author has made an attempt to develop four simple and rapid spectrophotometric methods for the estimation of GFX in bulk drugs and in pharmaceutical formulations. The first three methods. i.e. A, B and C, are based on the oxidation of the drug with Fe(III) and the estimation of Fe (II) produced after chelation with either 1,10-phenanthroline or 2,2'-bipyridyl or ferricyanide at 515, 520 and 760 nm, respectively. In the fourth method, molybdate is reduced to molybdenum blue which is determined at 825 nm. |
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