The mobile order solubility equation applied to polyfunctional molecules: The non-hydroxysteroids in aqueous and non...

The solubility equation for real solutions derived from the thermodynamics of mobile order in liquids is used to predict the solubility of non-hydroxysteroids in water and in common polar and nonpolar organic solvents. Strictly obtained on a thermodynamic basis, the model allows not only correct predictions of the solubilities from the knowledge of a limited number of characteristics of solutes and solvents, but also enables a better understanding of the solution process and of the factors that determine solubility. Some practical rules are derived which might help to orient the choice of a solvent for liquid pharmaceutical forms.