Entrapped transient chloroform solvates of bilastine

The knowledge about the solid forms landscape of Bilastine (BL) has been extended. The crystal structures of two anhydrous forms have been determined, and the relative thermodynamic stability among the three known anhydrous polymorphs has been established. Moreover, three chloroform solvates with variable stoichiometry have been identified and characterized, showing that S_3CHCl3-H2O and S_CHCl3 can be classified as transient solvateswhich transforminto the newchloroform solvate SCHCl3-H2O when removed fromthemother liquor. The determination of their crystal structures from combined single crystal/synchrotron X-ray powder diffraction data has allowed the complete characterization of these solvates, being two of them heterosolvates (S_3CHCl3-H2O and S_CHCl3-H2O) and S_CHCl3 a monosolvate. Moreover, the temperature dependent stability and interrelation pathways among the chloroform solvates and the anhydrous forms of BL have been studied.