Enhancing Norfloxacin’s Solubility and Antibacterial Activity through Pharmaceutical Salt Formation with Fluorobenzoic Acids

Norfloxacin (NOR), a broad-spectrum fluoroquinolone antibiotic, is widely used to treat bacterial infections.However, its clinical application is hindered by poor aqueous solubility and low oral bioavailability.To address these limitations, this study developed two novel pharmaceutical salts of NOR using 4fluorobenzoic acid (4-FA) and 2-fluorobenzoic acid (2-FA) as counterions.The salts were synthesized via slow evaporation crystallization, and their structures were characterized by single-crystal X-ray diffraction (SCXRD).Comprehensive solid-state analyses, including powder X-ray diffraction (PXRD), Fourier-transform infrared (FT-IR) spectroscopy, and differential scanning calorimetry (DSC), confirmed the successful formation of the salts.Notably, the salt formation significantly improved NOR's solubility and dissolution behavior.Furthermore, these modifications enhanced NOR's antibacterial efficacy, as evidenced by stronger bacterial inhibition and reduced minimum inhibitory concentration (MIC) values.This study demonstrates a promising strategy for optimizing the biopharmaceutical performance of NOR through salt formation.