Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

Solvates of sulindac were obtained by crystallization from acetone, chloroform, dichloromethane andtetrahydrofuran, but not from water, methanol, ethanol and propanols, acetonitrile and ethyl acetateand were studied by thermal (differential scanning calorimetry DSC, thermogravimetry TGA andthermomicroscopy HSM) and spectroscopic (micro-Raman, SEM, X-EDS) analysis.It emerged from the thermal analysis that the samples thus obtained are not simple solvates orpseudo-polymorphs, but rather polymorph solvates, where the new form could be evidenced only afterdesolvation in controlled conditions, since the desolvation and polymorph transition processes occurtogether and in the thermogram the endotherms overlap. Desolvation, that is accompanied by decol-oration of the sample from orange to yellow, enabled calculation of the solvate stoichiometry by the TGAparameters. The polymorph obtained from desolvation of the acetone solvate displays different ther-mal parameters from those obtained with chloroform, dichloromethane and tetrahydrofuran solvates.According to the solvents employed for crystallization, these thermal events leave sulindac in the form Ior both I and II, outlining the very complex nature of the solid state of this drug. A new unsolvated poly-morph form was directly obtained applying the technique of the quasi emulsion solvent diffusion (QESD).These results could open new perspectives in the use of the anti-inflammatory/anti-cancer sulindac interms of formulation and mode of delivery and release.