Measurement and correlation for solubility of levofloxacin in six solvents at temperatures from 288.15 to 328.15 K

The solubility of levofloxacin in six solvents including ethanol, 1-propanol, 2-propanol, 1-butanol, acetic acid and ethyl acetate in the temperature range of 288.15–328.15 K at atmospheric pressure was measured by a balance method. It is indicated that the solubility data of levofloxacin in selected solvents increase with increasing temperature. The experimental solubilities were correlated by the modified Apelblat equation which fits well with the experimental data. Further the molecular modeling studies indicate that the higher solubility of levofloxacin in acetic acid is due to the stronger hydrogen bonds between the solute and solvent molecules. The dissolution enthalpy, dissolution entropy and the molar Gibbs energy were predicted. Finally, the solubility data were correlated using two local composition models of NRTL 1 and UNIQUAC.