Solubility of atenolol in aqueous propylene glycol mixtures revisited: IKBI preferential solvation analysis

The preferential solvation parameters of atenolol in aqueous binary mixtures of propylene glycol (PG) were derived from reported molar solubility values after conversion to mole fractions by using the inverse Kirkwood-Buff integrals method. This drug is sensitive to preferential solvation effects in this binary system. The preferential solvation parameter by PG (delta x(1,3)) is negative in water-rich mixtures but positive in mixtures of 0.20 < x(1) < 1.00. It is conjecturable that hydrophobic hydration around the non-polar methyl and phenylene groups of this drug observable in water-rich mixtures could play a relevant role in drug solvation. Otherwise, in mixtures of 0.20 < x(1) < 1.00, the preferential solvation by PG could be due to the acidic behaviour of atenolol.