Correlation of Solubilities of Hydrophilic Pharmaceuticals versus Dielectric Constants of Binary Solvents

In this paper, the polarity of binary solvents was studied by the sum law of cube roots of the dielectric constant. During the antisolvent crystallization process, the composition of the binary solvents and their dielectric constants changed simultaneously. These results demonstrated that variation of the solubility is dependent on the polarity of the binary solvents. On the basis of experiments, a new model was put forward to quantitatively describe the relationship between the solubility of hydrophilic pharmaceuticals and the dielectric constants of the binary solvents. Furthermore, this model was tested and verified by solubility data of other pharmaceuticals published in the literature with high accuracy.