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Parametric Rietveld refinement using humidity as a 'non-crystallographic' parameter for in situ characterization of pharmaceutical amorphous content

Grant number: 12/09935-0
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): February 04, 2013
Effective date (End): February 03, 2014
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal Investigator:Carlos de Oliveira Paiva Santos
Grantee:Rafael Silva Nunes
Supervisor abroad: John S. O. Evans
Home Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
Local de pesquisa : Durham University (DU), England  
Associated to the scholarship:10/08789-4 - Preparation of a standard material for quantification of amorphous in crystalline pharmaceuticals without knowledge of the crystal structure, BP.DR


The goal of Mr. Nunes' to visit Durham is develop Parametric Rietveld refinement as a model of structural adjustment using humidity as 'non-crystallographic' refinable parameter. The aim is to characterize the amorphous content of pharmaceutical molecules by in situ x-ray diffraction using LiF and/or Li2CO3 as internal standards. Temperature and time will also be used as external parameters. Amorphous drug forms and their bioavailability are of significant interest to the pharmaceutical industry, making this a timely and relevant investigation.The lattice distortion due to humidity will be modelled using the software TOPAS-Academic, based on the concepts introduced by Kanzaki for a theoretical description of defects in fcc lattices, and the intensity attenuation correlated with static Debye-Waller factor.A polymorphic map taking into account the amorphous fraction generated in each transformation between forms A, B and C of Mebendazole (MBZ) will be determined, and kinetic studies of their interconversion will be studied by parametric Rietveld refinement. (AU)