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

• Grant number: 12/09935-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: February 04, 2013
• End date: 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: John S. O. Evans
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Institution abroad: 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

Abstract

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)