Etude du changement de phase solide-liquide en relation avec la stabilite thermique des formes polymorphes et pseudopolymorphes du lorazepam et identification spectrale

Thermal decomposition of lorazepam begins by lose of a water mole between two groups NH-OH and occurs at different temperatures depending on the formes of polymorphs. Melting temperature of a form can be determined only if it is below that of decomposition.The thermoanalytical and spectral study of lorazepam commercial drugs (a) and (b) recrystallisation product at 20°C in benzine (c), in carbon tetrachlorid (d), in acetonitrile (e) were carried out.Thermal behaviour, RX diffraction, IR spectroscopy allow us to identify polymorph (a, b, c) and two solvates (d and e). The solvates stoechiometry (d and e) has been determined by thermogravimetry (3-2) d, (2-1) e, and confirmed by magnetic nuclear resonance for (e).

Nous exprimons nos vifs remerciements à Madame Eliane Toreilles, Directeur de recherche au CNRS (Laboratoire de Chimie Organiques UA 458 CNRS, Ecole Nationale Supérieure de Chimie de Montpellier) pour sa collaboration personnelle en spectroscopie.