Extended Hildebrand solubility approach: testosterone and testosterone propionate in binary solvents.

Solubilities of testosterone and testosterone propionate in binary solvents composed of the inert solvent, cyclohexane, combined with the active solvents, chloroform, octanol, ethyl oleate, and isopropyl myristate, were investigated with the extended Hildebrand solubility approach. Using multiple linear regression, it was possible to obtain fits of the experimental curves for testosterone and testosterone propionate in the various binary solvents and to express these in the form of regression equations. Certain parameters, mainly K and log alpha 2, were employed to define the regions of self-association, nonspecific solvation, specific solvation, and strong solvation or complexation.