Bilinear model for the prediction of drug solubility in ethanol/water mixtures

A new bilinear function that accounts for the disparity between the log-linear and parabolic models for cosolvent solubilization is presented, where ethanol was used as the model cosolvent. This accounts for both the initial and terminal slopes in the ethanol/water solubility profiles of semi-polar solutes. The proposed model has only two fitted parameters σA and σB, which represent the initial and terminal asymptotes in the solubility profiles. The bilinear function can also model the ethanol/water solubility profile more accurately than the log-linear model and a general parabolic model. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association.