Thermodynamic solubility and density of sildenafil citrate in ethanol and water mixtures: Measurement and correlation at various temperatures

Solubility of sildenafil citrate (SC) in binary aqueous mixtures of ethanol (EtOH) was studied at 293.2, 298.2, 303.2, 308.2 and 313.2 K. Density of the SC saturated solutions over the entire solvent composition and temperature range was measured using a pycnometer. The effect of solvent composition on solubility, enthalpy, entropy and Gibbs energy was studied according to van't Hoff and Gibbs equations. The experimental solubility and densities were used to estimate solubility in the investigated solvent system using the van't Hoff and Jouyban-Acree models.