Ionic Cocrystals of Etiracetam and Levetiracetam: The Importance of Chirality for Ionic Cocrystals

A striking variety of anhydrous and hydrated ionic cocrystals (ICCs) of the enantiopure antiepileptic drug (AED) levetiracetam and of its racemic intermediate etiracetam with the pharmaceutically acceptable salts CaCl2 and MgCl2 was synthesized and structurally characterized. The difference in the interaction of enantiopure and racemic compounds of interest with the inorganic salts was investigated. Variable-temperature X-ray powder diffraction (VT-XRPD) and calorimetric analyses (TGA and DSC) of all obtained ICCs showed a significant improvement in thermal stability with respect to pure racetams.