Predicting Aqueous Solubility: The Role of Crystallinity

This paper revisits the role of crystallinity in predicting the aqueous solubility of a wide variety of organic compounds. Box and Comer (Current Drug Metabolism, 2008, 9, 869-878) fitted solubility data for 86 drugs to an equation based solely on log P. The General Solubility Equation of Jain and Yalkowsky, which accounts for the crystal lattice energy, was applied to the same data set and gives more accurate solubility predictions. In this simple comparison between two solubility prediction methods, we show that log P alone is only half of the solution, and that there is a need to include the melting point when dealing with crystalline solutes.