Formation, Physicochemical Characterization, and Thermodynamic Stability of the Amorphous State of Drugs and Excipients

Author(s): Piera Di Martino , Federico Magnoni , Dolores Vargas Peregrina , Maria Rosa Gigliobianco , Roberta Censi , Ledjan Malaj .

Journal Name: Current Pharmaceutical Design

Volume 22 , Issue 32 , 2016

Abstract:

Drugs and excipients used for pharmaceutical applications generally exist in the solid (crystalline or amorphous) state, more rarely as liquid materials. In some cases, according to the physicochemical nature of the molecule, or as a consequence of specific technological processes, a compound may exist exclusively in the amorphous state. In other cases, as a consequence of specific treatments (freezing and spray drying, melting and co-melting, grinding and compression), the crystalline form may convert into a completely or partially amorphous form. An amorphous material shows physical and thermodynamic properties different from the corresponding crystalline form, with profound repercussions on its technological performance and biopharmaceutical properties. Several physicochemical techniques such as X-ray powder diffraction, thermal methods of analysis, spectroscopic techniques, gravimetric techniques, and inverse gas chromatography can be applied to characterize the amorphous form of a compound (drug or excipient), and to evaluate its thermodynamic stability. This review offers a survey of the technologies used to convert a crystalline solid into an amorphous form, and describes the most important techniques for characterizing the amorphous state of compounds of pharmaceutical interest.

Keywords: Amorphous state, glass transition temperature, thermal analysis, X-ray powder diffraction, thermal methods of analysis, spectroscopic techniques, gravimetric techniques, inverse gas chromatography.

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Article Details

VOLUME: 22
ISSUE: 32
Year: 2016
Page: [4959 - 4974]
Pages: 16
DOI: 10.2174/1381612822666160726105658
Price: $58

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