Effect of Ethanol on the Solubility and Apparent Specific Volume of Sodium Sulfadiazine in Aqueous Mixtures

The main objective of this research was to correlate the equilibrium solubility of sodium sulfadiazine in several {ethanol (EtOH, 1) + water (2)} mixtures reported in mass/volume and mass/mass percentages at different temperatures. Aqueous solubility of sodium sulfadiazine decreases almost linearly with decreasing temperature, but it decreases non-linearly with the addition of EtOH to water. Logarithmic solubility was adequately correlated with a bivariate model involving temperature and mixture composition. These solubility results were also well correlated with the Jouyban–Acree-based models. Moreover, an adapted version of the Jouyban–Acree model was used to represent the density of the saturated solvent mixtures at different temperatures. Furthermore, the apparent specific volumes of this drug at saturation were also calculated from densities of saturated solutions and cosolvent mixtures free of drug as well as from the respective mixture compositions. These findings provide valuable insights into the solubility and volumetric behavior of sodium sulfadiazine, which could be useful for pharmaceutical formulation and process optimization.