Epitaxial 2D nucleation of the stable polymorphic form of the steroid 7αMNa on the metastable form: Implications for Ostwald's rule of stages

This paper presents in situ observations of the epitaxial nucleation and growth of the stable polymorph of a steroid, 7αMna, on a specific face of the metastable form at low supersaturation, using optical microscopy and in situ Raman spectroscopy. The presence of the metastable polymorph is essentia...

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Bibliographic Details
Published in:International journal of pharmaceutics 2006-02, Vol.309 (1), p.16-24
Main Authors: Stoica, C., Verwer, P., Meekes, H., Vlieg, E., van Hoof, P.J.C.M., Kaspersen, F.M.
Format: Article
Language:English
Subjects:
Biological and medical sciences
Epitaxial nucleation
General pharmacology
Medical sciences
Metastable zone
Pharmaceutical technology. Pharmaceutical industry
Pharmacology. Drug treatments
Polymorphism
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Summary:This paper presents in situ observations of the epitaxial nucleation and growth of the stable polymorph of a steroid, 7αMna, on a specific face of the metastable form at low supersaturation, using optical microscopy and in situ Raman spectroscopy. The presence of the metastable polymorph is essential for the nucleation and growth of the stable one. The order of the metastable zones of the stable and metastable polymorphs is reversed for the epitaxial growth process as compared to the case of 3D nucleation. The rate of transformation of the metastable polymorph to the stable one can be controlled by the supersaturation.
ISSN:0378-5173
1873-3476
DOI:10.1016/j.ijpharm.2005.10.041