Determination and correlation of solubility of pranlukast hemihydrate in five organic solvents at different temperatures and its dissolution properties

In this study, the solubility of pranlukast hemihydrate in methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol was determined at temperatures ranging from 298.15 to 323.15 K by a solid-liquid equilibrium method. The measured solubility data of pranlukast hemihydrate were correlated with the modified Apelblat and Van't Hoff models. The maximum mole fraction solubility of pranlukast hemihydrate in 1-butanol was observed to be 26.39 × 10− 5 at 323.15 K, followed by that in 1-propanol (9.63 × 10− 5 at 323.15 K), ethanol (6.18 × 10− 5 at 323.15 K), 2-propanol (5.71 × 10− 5 at 323.15 K), and methanol (3.96 × 10− 5 at 323.15 K). Interestingly, the solubility of pranlukast hemihydrate increases with a decrease in dielectric constant of the primary alcohols. The measured solubility data of pranlukast hemihydrate correlated well with the modified Apelblat equation. In addition, thermodynamic analysis indicated an endothermic and spontaneous dissolution behavior of pranlukast hemihydrate in the studied solvents. Therefore, these experimental solubilities and correlation equations can be useful in the purification/crystallization and formulation study of pranlukast hemihydrate in laboratories and related industries.