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-07-6), cephalexin·H 2 O (CAS No. 23325-78-2), ciprofloxacin HCl (CAS No. 86393-32-0), levofloxacin (CAS No. 100986-85-4), and metronidazole (CAS No. 443-48-1). All of these compounds are antimicrobial pharmaceuticals. In addition, ciprofloxacin HCl and levofloxacin

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The objective of the current study is to develop a validated specific stability-indicating isocratic reversed-phase liquid chromatographic method for the quantitative determination of levofloxacin and its related substances in pharmaceutical dosage forms in the presence of degradation products and its process-related impurities. Forced degradation studies were performed on levofloxacin as per the International Conference on Harmonisation (ICH)-prescribed stress conditions using acid, base, oxidative, water hydrolysis, thermal stress and photolytic degradation to show the stability-indicating power of the method. Significant degradation was observed during oxidative stress; minor degradation was observed in acidic stress and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the spiked impurity solution. The analysis was carried out with a 50 mm length × 4.6 mm i.d., 3.0 μm particle size YMC Pack Pro-C18 column using the mobile phase consisting of a mixture of 1.0% (v/v) triethylamine in water with pH adjusted to 6.30, using orthophosphoric acid, methanol and acetonitrile (7.7:1.3:1.0) pumped at a flow rate of 0.8 mL min−1 with ultraviolet (UV) detection at 235 nm. The limit of detection and the limit of quantification for the levofloxacin and its process-related impurities were established. The stressed test solutions were assayed against the qualified working standard of levofloxacin and the mass balance in each case was in between 99.1% and 99.9%, indicating that the developed liquid chromatography (LC) method was a stability-indicating technique. Validation of the developed LC method was carried out as per ICH requirements.

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. [26] S. Gudlawar , J. Dwivedi , N. Venugopal , A selective and sensitive UPLC-MS/MS method for simultaneous determination of four genotoxic impurities in levofloxacin

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A novel economic thin-layer chromatographic procedure for stereoselective separation of racemic mixtures of each of zopiclone and ofloxacin, and determination of their enantiomers: eszopiclone, (+)-(S)-zopiclone, and levofloxacin, (−)-(S)-ofloxacin, was described. The method was based on using normal plates and hydroxy propyl-β-cyclodextrin (HP-β-CD) as chiral mobile phase additive (CMPA). The spots were detected under UV lamp 254 nm, followed by densitometric measurements at 304 and 330 nm for (+)-(S)-zopiclone and (−)-(S)-ofloxacin, respectively. The mobile phase enabling successful resolution of the drugs was ethanol-acetonitrile-glacial acetic acid-diethylamine-distilled water containing 0.5% HP-β-CD (4:2:3:1:1, by volume), pH 4, for zopiclone and ethanol-acetonitrile-glacial glacial acetic acid-diethylamine-distilled water containing 0.3% HP-β-CD (4:4:3:2:1 by volume), pH 4.5, for ofloxacin at 25 ± 2°C. All variables affecting the resolution, such as concentration of different chiral selectors, temperature, and pH, were investigated, and the conditions were optimized. Furthermore, some thermodynamic parameters were calculated. The procedure provided a linear response over the concentration range of 1–4 and 2–7 μg spot−1 for determination of pure active isomers, (+)-(S)-zopiclone and (−)-(S)-ofloxacin, respectively, with acceptable precision (relative standard deviation [% RSD] <2.0). The developed method was validated and proved to be robust. The proposed method was found to be selective and accurate for the identification and quantitative determination of enantiomeric purity of the two active isomers in their drug substances and drug products.

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Journal of Thermal Analysis and Calorimetry
Authors: Mihaela Badea, Rodica Olar, Dana Marinescu, Valentina Uivarosi, Teodor Nicolescu, and Daniela Iacob


A series of new complexes with mixed ligands of the type RuLm(DMSO)nCl3·xH2O ((1) L: oxolinic acid (oxo), m = 1, n = 0, x = 4; (2) L: pipemidic acid (pip), m = 2, n = 1, x = 2; (3) L: enoxacin (enx), m = 2, n = 1, x = 0; (4) L: levofloxacin (levofx), m = 2, n = 2, x = 8; DMSO: dimethylsulfoxide) were synthesized and characterized by chemical analysis, IR and electronic data. Except oxolinic acid that behaves as bidentate, the other ligands (quinolone derivatives and DMSO) act as unidentate. Electronic spectra are in accordance with an octahedral stereochemistry. The thermal analysis (TG, DTA) in synthetic air flow elucidated the composition and also the number and nature of both water and DMSO molecules. The TG curves show 3–5 well-separated thermal steps. The first corresponds to the water and/or DMSO loss at lower temperatures followed either by quinolone thermal decomposition or pyrolisys at higher temperatures. The final product is ruthenium(IV) oxide.

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containing cefixime, cefuroxime axetil, cephalexin·H 2 O, ciprofloxacin HCl, levofloxacin, and metronidazole. In this article, the application of the transfer process is extended by seven products containing eight important drugs of different types

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