Pharmaceutical cocrystals and salts of enrofloxacin: Structure and properties

· Novel enrofloxacin cocrystals and salts prepared through slow solvent evaporation. · All salts and cocrystals were completely characterized by PXDR, FTIR, and DSC. · The crystal structures of salts and cocrystals are determined by SCXRD. · The solubility of the parent drug improved through cocrystallization method. Enrofloxacin, a second-generation quinolone broad-spectrum antimicrobial, has limited application because of its poor solubility. The purpose of this paper was to investigate the structure and properties of newly generated enrofloxacin salts and cocrystals. The crystal structures and properties of enrofloxacin vanillin cocrystal (EFC-VNL) (1), enrofloxacin sebacate (EFC-SBA) (2), enrofloxacin malate trihydrate (EFC-MAL-3H 2 O) (3), enrofloxacin adipate-EtOH Salt Solvate (EFC-ADH) (4) were characterized by single crystal X-ray diffraction, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and thermal difference analysis. All compounds were synthesized by slow volatilization of organic solvents at room temperature. The solubility of these salts and cocrystals in water was measured by high-performance liquid chromatography. The results showed that the newly generated enrofloxacin cocrystals and salts had higher aqueous solubility than enrofloxacin.