Solubilities of carvedilol (CVD) in binary mixtures of (ethanol + propylene glycol (PG)) at 298.2, 303.2, 308.2, and 313.2 K are reported. The modified versions of the van't Hoff and Gibbs equations were used to calculate the thermodynamic properties (enthalpy (ΔH°), entropy (ΔS°), and Gibbs energy (ΔG°) standard changes of solutions) for CVD dissolved in (ethanol (1) + PG (2)) mixtures from the solubility data. The solubility data of CVD in (ethanol (1) + PG (2)) at different temperatures were correlated using different mathematical models, i.e., the Jouyban−Acree model, a combination of the Jouyban−Acree model with the van't Hoff model, and two modified versions of the Jouyban−Acree model. Solubility data of seven drugs in (ethanol (1) + PG (2)) at different temperatures were used to develop a quantitative structure−property relationship model for predicting solubility in solvent mixtures. In addition, enthalpy−entropy compensation using ΔH°vs ΔG°a nd ΔH°vs TΔS°which explains the mechanism of cosolvency at different temperatures was discussed.

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Preferential solvation parameters of etoricoxib in several aqueous cosolvent mixtures were calculated from solubilities and other thermodynamic properties by using the IKBI method. Cosolvents studied were as follows: 1,4-dioxane, N,N-dimethylacetamide, 1,4-butanediol, N,Ndimethylformamide, ethanol and dimethyl sulfoxide. Etoricoxib exhibits solvation effects, being the preferential solvation parameter δx 1,3 , negative in water-rich and cosolvent-rich mixtures but positive in mixtures with similar proportions of both solvents. It is conjecturable that the hydrophobic hydration in water-rich mixtures plays a relevant role in drug solvation. In mixtures of similar solvent proportions where etoricoxib is preferentially solvated by the cosolvents, the drug could be acting as Lewis acid with the more basic cosolvents. Finally, in cosolvent-rich mixtures the preferential solvation by water could be due to the more acidic behaviour of water. Nevertheless, the specific solutesolvent interactions in the different binary systems remain unclear because no relation between preferential solvation magnitude and cosolvent polarities has been observed.

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