Measurement and correlation of the solubility of two steroid drugs in supercritical carbon dioxide using semi empirical models

The solubilities of desoxycorticosterone acetate (DA) and clobetasole propionate (CP) in supercritical carbon dioxide (SC-CO2) were measured at temperature ranging from (308 to 348) K and pressures from (12.2 to 35.5) MPa using a static method. The mole fraction solubilities ranged from 10−7 to 13.93 × 10−5. The crossover region was observed for DA and CP at 24.3 and 25.3 MPa, respectively. Solubility data were correlated using four semi-empirical density-based models (Chrastil, Bartle, Kumar, Johnston (K–J) and Mendez-Santiago and Teja (M–T) models). The average absolute relative deviations (AARD%) ranged from 9.3 to 13.6; 8.9 to 11.9; 6.5 to 10.3 and from 10.4 to 13.4 for Chrastil, Bartle, K–J and M–T models, respectively. A comparison among the four models revealed that the K–J model gave much better correlation of the solubilities in comparison with other models. Using the correlation results, the heat of drug–CO2 solvation and that of drug vaporization was separately approximated in the range of −24.2 to −24.5 and 63.8 to 64.8 kJ mol−1. The correlation results showed good agreement with the experimental data.