Solubility of sulphadiazine in some {Carbitol® (1) + water (2)} mixtures: determination, correlation, and preferential solvation

The mole fraction solubility of sulphadiazine (SD) in {Carbitol (R) (1) + water (2)} binary solvent mixtures at different temperatures from (278.15 to 313.15) K was determined. Solubility values were correlated with the combined nearly ideal binary solvent/Redlich-Kister, modified Wilson and Jouyban-Acree models. Preferential solvation parameters of SD by Carbitol (R) (delta x (1,3)) were derived from their thermodynamic solution properties using the inverse Kirkwood-Buff integrals method. delta x (1,3) values are negative in water-rich mixtures but positive in Carbitol (R) mole fractions higher than 0.12. In the former case is conjecturable that hydrophobic hydration around non-polar groups of SD plays a relevant role in drug solvation.