Measurement and correlation of solubility and dissolution properties of flunixin meglumine in pure and binary solvents

• The solubility data of flunixin meglumine in pure and mixed solvents were experimentally determined.
• Thermodynamic properties of flunixin meglumine dissolution process were calculated.
• The experimental solubility data of flunixin meglumine were correlated by three models and a new model was proposed.

The solubility of flunixin meglumine (FM) in six pure solvents and binary solvents of ethanol + isopropanol was measured over the temperature ranged from 283.15 K to 328.15 K by using a static gravimetric method. It is positively correlated with temperature and negatively correlated with the molar fraction of isopropanol. The modified Apelblat equation was used to correlate the experimental solubility in pure solvents. Dissolution properties based on the modified Apelblat equation were calculated and discussed. The solubility in binary solvents at various temperatures was well correlated by the nearly ideal binary solvent (NIBS)/Redlich–Kister model. In addition, in order to correlate the solubility to both the composition and temperature in mixed solvents, a new model related to dielectric constant was proposed.

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