Development and validation spectroscopic methods for the determination of lomefloxacin in bulk and pharmaceutical formulations

Abstract

Four simple, sensitive spectrophotometric and spectrofluorimetric methods (A-D) for the determination of antibacterial drug lomefloxacin (LMFX) in pharmaceutical formulations have been developed. Method A is based on formation of ternary complex between Pd(II), eosin and LMFX in the presence of methyl cellulose as surfactant and acetate-HCl buffer pH 4.0. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 530 nm. Methods B and C are based on redox reaction between LMFX and KMnO₄ in acid and alkaline media. In indirect spectrophotometry method B the drug solution is treated with a known excess of KMnO₄ in H₂SO₄ medium and subsequent determination of unreacted oxidant by reacting it with safronine O in the same medium at λ_max = 520 nm. Direct spectrophotometry method C involves treating the alkaline solution of LMFX with KMnO4 and measuring the bluish green product at 604 nm. Method D is based on the chelation of LMFX with Zr(IV) to produce fluorescent chelate. At the optimum reaction conditions, the drug-metal chelate showed excitation maxima at 280 nm and emission maxima at 443 nm. The optimum experimental parameters for the reactions have been studied. The validity of the described procedures was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed methods were successfully applied for the determination of the selected drug in pharmaceutical preparations with good recoveries.