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dc.contributor.authorGrooff, Driekus
dc.contributor.authorLiebenberg, Wilna
dc.contributor.authorDe Villiers, Melgardt M.
dc.date.accessioned2012-10-29T08:10:46Z
dc.date.available2012-10-29T08:10:46Z
dc.date.issued2011
dc.identifier.citationGrooff, D. et al. 2011. Preparation and transformation of true nifedipine polymorphs: investigated with differential scanning calorimetry and X-Ray diffraction pattern fitting methods. Journal of Pharmaceutical Sciences,100(5):1944-1957. [http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291520-6017/]en_US
dc.identifier.issn0022-3549
dc.identifier.issn1520-6017 (Online)
dc.identifier.urihttp://hdl.handle.net/10394/7658
dc.description.abstractThe amorphous → metastable and metastable → stable crystalline phase transitions of nifedipine and their relationship with polymorph composition during storage at controlled temperature/humidity conditions were investigated. Metastable form C was produced from both differential scanning calorimetry (DSC) thermal treatment and storage [22 °C/0% and 75% relative humidity (RH)] of the amorphous form. Amorphous conversion rate accelerated with storage temperature up to 40 °C, but a further 8 °C increase to 48 °C (3 °C above the glass transition) resulted in a more than 12-fold decrease in amorphous conversion rate. DSC and X-Ray diffraction (XRD) analysis revealed a faster amorphous conversion rate relative to the metastable crystal transformation with 75% RH having a greater accelerative effect on the former. Relative phase quantification from XRD pattern fitting included the use of integrated peak intensities of the crystalline phases, Rietveld and the Rietveld-based partial or no known crystal structures method. Kinetic analysis with Johnson-Mehl-Avrami equation indicated that the accelerated amorphous conversion in 75% RH was associated with a 10-fold increase in rate constant with dimensional growth little affected. The smaller rate increase for metastable crystal conversion was associated with an increased dimensional growth while the rate constant was little affected.en_US
dc.description.urihttp://dx.doi.org/10.1002/jps.22419
dc.language.isoenen_US
dc.publisherWileyen_US
dc.subjectNifedipineen_US
dc.subjectphysical stabilityen_US
dc.subjectpolymorphismen_US
dc.subjectamorphousen_US
dc.subjectkineticsen_US
dc.subjecttransformationen_US
dc.titlePreparation and transformation of true nifedipine polymorphs: investigated with differential scanning calorimetry and X-Ray diffraction pattern fitting methodsen_US
dc.typeArticleen_US


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