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Solid state characterization of olanzapine polymorphs using vibrational spectroscopy

A.P. Ayala (a,b), H.W. Siesler (a), R. Boese (c), G.G. Hoffmann (a), G.I. Polla (d), D.R. Vega (d)

(a) Department of Physical Chemistry, University of Duisburg-Essen, Essen D45117, Germany
(b) Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, 60.455-900 Fortaleza, CE, Brazil
(c) Institut für Anorganische Chemie, Universität Duisburg-Essen, Universitätsstr. 5-7, D-45117 Essen, Germany
(d) Unidad de Actividad Física, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires, Argentina


International Journal of Pharmaceutics 326 (2006) 69–79


Abstract

FT-Raman, infrared and near infrared investigations of two polymorphs of olanzapine are presented, establishing the main features that allow the discrimination of these crystalline forms using vibrational spectroscopic methods. Ab initio calculations on the basis of the density functional theory were used to determine the stable conformations. The calculated vibrational spectra were compared to the experimental ones in order to identify the conformers corresponding to each polymorph and to assign the vibrational bands to the internal vibrations of the olanzapine molecule. Our results support the hydrogen bonding pattern proposed by the reported crystalline structure and provide valuable information on the structural and thermodynamical relationship between the investigated polymorphs.

Keywords: Olanzapine; Polymorphism; Raman spectroscopy; Infrared spectroscopy; Hydrogen
bonding; Ab initio; DFT

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