Preferential solvation of etoricoxib in some aqueous binary cosolvent mixtures at 298.15 K

ABSTRACT

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,N-dimethylformamide, 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 solute–solvent interactions in the different binary systems remain unclear because no relation between preferential solvation magnitude and cosolvent polarities has been observed.

KEYWORDS:

• Etoricoxib
• binary cosolvent mixtures
• inverse Kirkwood–Buff integrals
• preferential solvation

Disclosure statement

No potential conflict of interest was reported by the authors.