The interactions and thermodynamic parameters of lenvatinib mesylate in pure and mixed solvents at several temperatures

The objective of the present study was to investigate the effect of solvent properties on the solubility profile and thermodynamic dissolution properties of lenvatinib mesylate. The maximum solubility of lenvatinib mesylate in pure solvents is observed in methanol 4.993 × 10-4 and the lowest in ethyl acetate 8.610 × 10-5 at 313.15 K. The mole fraction solubility in alcohols is greater than that in ethyl acetate, moreover, the solubility in methanol increased about 9.11-fold in the research temperature interval. In mixtures of (methanol /ethanol + ethyl acetate), the solubility of lenvatinib mesylate increased with the increasing mass fraction of alcohols at a given temperature. The results obtained from KAT-LSER model indicate the hydrogen bond acidity and dipolarity/polarizability have a greater influence on the solubility. The results of relative average deviation (RAD) suggest that the modified Apelblat equation and CNIBS/R-K model are suitable to describe the solubility profile. The positive values of apparent thermodynamic properties indicates that the dissolution of lenvatinib mesylate is an endothermic and entropy-driven process in all investigated solvents. The values of apparent standard dissolution enthalpy (ΔHsolo) ranges from 39.04 kJ·mol−1 to 44.26 kJ·mol−1. The maximum value of ΔGsolo is observed in methanol and minimum data in ethyl acetate, which means that the dissolution process is more favorable in ethyl acetate. Moreover, the apparent standard dissolution enthalpy was the main contributor to the Gibbs free energy during the dissolution process. The obtained solubility data and model parameters of lenvatinib mesylate in commonly used solvents could be useful in the purification and recrystallization.