Comprehensive insight into solubility, dissolution properties and solvation behaviour of dapsone in co-solvent solutions

This research was mainly committed to the solubility profile, dissolution properties and solvation behavior for the systems formed by dapsone in aqueous solutions of ethanol/acetone/methanol (1) and nonaqueous solution of ethyl acetate (1) + ethanol (2) accompanied by numerous computational methodology. All experiments for solubility were conducted by using a shake-flask method at pressure p = 101.2 kPa and temperatures from 278.15 to 323.15 K. For each solvent solution system, the equilibrium solubility in magnitude of dapsone was recorded as highest in neat ethanol/ethyl acetate/methanol/acetone (1) at 323.15 K; and lowest in neat ethanol (2) or water (2) at 278.15 K. The three-dimensional Hansen solubility parameter was utilized here to investigate solubility performance. Numerous common relationships including modified van't Hoff Jouyban-Acree model, mixture response surface model, Jouyban-Acree model, and modified Wilson model provided acceptable correlation consequences for the solubility magnitudes obtained with relative average deviations of < 12.33 %. The solubility magnitude at temperature of 298.15 K was also studied by the extended Hildebrand solubility approach, gaining RAD of < 3.24 %. By consideration of some accessible solution properties, the preferential solvation of dapsone was further examined through quantitation by employing the inverse Kirkwood-Buff integrals way. The positive parameters of preferential solvation in ethanol/acetone/methanol-rich and intermediate composition solutions indicates that the drug dapsone is preferentially solvated by ethanol/acetone/methanol. It can be speculated that dapsone performs as Lewis acid behavior with ethanol/acetone/methanol molecules in above composition regions. Nevertheless preferential solvation of dapsone is made neither by ethanol nor by ethyl acetate in the ethyl acetate + ethanol solution. The dissolution of dapsone in all studied systems was endothermic and entropy-driven process. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This research focused on the solubility and solvation behavior of dapsone in different solvent systems. The highest solubility of dapsone was found in neat ethanol/ethyl acetate/methanol/acetone, while the lowest solubility was in neat ethanol or water. Various common relationships were used to analyze the solubility data obtained from the experiments.