Physicochemical study of the solid forms of a new drug

GV150526A is a new drug recently developed by GlaxoWellcome. It belongs to a novel group of 2-carboxyindole derivatives and is therapeutically effective in the treatment or prevention of CNS disorders resulting from neurotoxic damage. We present a physicochemical characterization of the three solid forms (hydrates) of GV150526A carried out mainly by thermal methods. It is shown that: (1) the different forms can be qualitatively and quantitatively distinguished by their thermal properties; (2) dehydration is followed or accompanied by a structural relaxation of the substrate that takes place at different rates and with different enthalpies in the three forms; (3) two of the solid forms can be converted into a phase that is thermodynamically stable at room temperature by partial dehydration/rehydration in a solid/vapor process.