Solubility Screening on a Series of Structurally Related Compounds: Cosolvent-Induced Changes on the Activity Coefficient of Hydrophobic Solutes
Yasuhiro Miyako, Hideaki Tai, Kaori Ikeda, Ryuich Kume, Rodolfo Pinal · Drug Development and Industrial Pharmacy · 2008
A homologous series of solutes was chosen as a model for a group of structurally related compounds with different physicochemical properties, as is commonly the case during the screening of potential drug candidates. Thermal properties of the crystalline solutes and solubility determinations were used to quantify the two independent factors that determine the solubility of organic compounds: crystallinity and hydrophobicity. A solubility screening study was conducted on the series. By expressing the obtained solubility enhancement expressed as changes in the activity coefficient, it is possible to visually compare the effect of different cosolvents. The results show the importance of solute-solvent polarity match. Polarity match between water miscible cosolvents and hydrophobic compounds is not truly attainable, but comparison of the screening results points out the closest matches (optimal effect), facilitating the systematic evaluation of solubilization approaches.