Supercritical CO2 and highly selective aromatase inhibitors: Experimental solubility and empirical data correlation

The solubility of highly selective and potent third-generation aromatase inhibitors includes the nonsteroidal agents letrozole and anastrozole and the steroid exemestane in supercritical carbon dioxide (SC-CO2.) has been investigated. The experiments were carried out using the simple and static method at pressures in the range of 12.1-35.5 MPa and temperatures ranging from 308 to 348 K. The mole fraction solubilities ranged from 0.22 x 10(-5) to 1.88 x 10(-4). Solubility data were correlated using six empirical models (Chrastil model, dV-A model, K-J model, Bartle model. Yu model and Gordillo model). The results showed that these models can be applied to satisfactory solubility predictions at different pressures and temperatures. A comparison among the six models revealed that the K-J, and Gordillo models gave much better correlations of the solubility data with an average absolute relative deviation (AARD%) ranging from 0.2 to 2.3 and from 1.6 to 2.5%, respectively. Using the correlation results, the heat of drug-CO2 solvation and that of drug vaporization was separately approximated in the range of -17.3 to -17.5 and 93.0-112.1 kJ mol(-1). (C) 2009 Elsevier B.V. All rights reserved.