Solubility and thermodynamic function of apremilast in different (Transcutol + water) cosolvent mixtures: Measurement, correlation and molecular interactions

Abstract

The solubility of apremilast (APM) in different “Transcutol® + water” cosolvent mixtures was determined and correlated at “T = 298.2 K–318.2 K” and ‘p = 0.1 MPa’. The experimental solubilities of APM were determined and correlated with “Apelblat, van't Hoff, Yalkowsky and Jouyban–Acree equations”. The maximum solubilities of APM in mole fraction were obtained in neat Transcutol (2.53 × 10−2 at T = 318.2 K). Based on activity coefficients, strong molecular interactions were obtained between APM and neat Transcutol in comparison with APM and neat water. “Apparent thermodynamic analysis” showed an “endothermic and entropy-driven dissolution” of APM.