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• Research the solubility of bezafibrate in pure and mixed solvents; • Solubility data was correlated by Jouyban-Acree model and van't Hoff-Jouyban-Acree model; • Discuss the influence of solvent properties on solubility. By using the saturation shake-flask method, the saturated solubility of bezafibrate in neat water, methanol, ethanol, n-propanol and isopropanol and aqueous co-solvent mixtures of methanol (1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and n-propanol (1) + water (2) was experimentally acquired at temperatures from 283.15 Kto 323.15 K and local atmospheric pressure. The maximum solubility magnitudes in mole fraction were recorded in the neat solvents of methanol/ethanol/ n -propanol/isopropanol for corresponding solutions. The mole fraction solubility was described mathematically by using the van't Hoff-Jouyban-Acree and Jouyban-Acree models. The largest value of relative average deviations was 6.23%; and, root-mean-square deviations, 8.92 × 10−5. The local mole fractions of water and co-solvent (methanol, ethanol, n -propanol or isopropanol) around the drug bezafibrate were quantitatively investigated by the use of Inverse Kirkwood–Buff integrals method. Results indicated that the bezafibrate was preferentially solvated by methanol (ethanol, n -propanol or isopropanol) in alcohol-rich and intermediate compositions in the alcohol mixtures; while in water-rich compositions, bezafibrate was preferentially solvated by water. The main factors relating to solvent effect were inspected through Kamlet and Taft linear solvation energy relationships, demonstrating that the cavity formation energy and dipolarity-polarizability in methanol solutions, cavity formation energy and basicity in ethanol solutions, and cavity formation energy in n -propanol (isopropanol) solutions played the principal role upon the bezafibrate solubility variation. [ABSTRACT FROM AUTHOR]

• The solubility of doxofylline in pure and binary solvents. • The solubility data were correlated by some thermodynamic models. • The effect of solvent properties on the solubility was analysed. • Some thermodynamic properties of dissolution process were evaluated. Crystallization and purification is an important step in drug preparation. In this work, the solubility of doxofylline in some pure and mixed solvents at T = 273.15–313.15 K was experimentally determined under 101.2 kPa. Infrared spectroscopy (IR) was used to evaluate the crystal form of doxofylline, and no solvates or new form formation were observed during the whole experiment. In pure solvent, the solubility data increased with the increasing temperature. At 313.15 K, the solubility maximum value (mole fraction) was obtained in ethyl acetate (3.8552 × 10−2), followed by acetonitrile (2.8699 × 10−2), ethanol (1.7179 × 10−2), methanol (0.7069 × 10−2), iso propanol (0.4928 × 10−2) and n-propanol (0.1533 × 10−2), and similar trend was obtained at each temperature studied. In mixture of (isopropanol + ethyl acetate), the solubility increased monotonically with the increasing mass fraction of ethyl acetate at each temperature studied. The Apelblat equation and λh equation were applied to correlate the solubility data in selected pure solvents. All relative average deviation (RAD) values in the modified Apelblat equation are less than those in λh equation. Therefore, modified Apelblat is more suitable for correlating the solubility profile in selected pure solvents. In addition, Jouyban-Acree model was used to evaluate the results in mixed solvents, and the RAD value is 5.48%. During the dissolution process, the apparent dissolution standard enthalpy (Δ H sol o), apparent molar standard Gibbs energy (Δ G sol o) and apparent dissolution standard enthalpy (Δ S sol o) were calculated. The values of Δ H sol o and Δ S sol o are all positive in this experiment, which indicates the dissolution process is not only endothermic but also entropy-driving. Moreover, the contribution of dissolution enthalpy, (% ξ H) is greater than entropy (% ξ TS ) to the change of dissolution Gibbs energy in the dissolution process. [ABSTRACT FROM AUTHOR]