Volume 2, Issue 1 (January 2005)

    The Role of TGA-DTA in the Initial Evaluation of the Solid State Forms for Pharmaceutical New Chemical Entities, Part 2: Evaluation of Mixed Forms

    (Received 24 May 2004; accepted 15 September 2004)

    Published Online: 2005

    CODEN: JAIOAD

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    Abstract

    TGA-DTA plays a central role in the strategy outlined for early evaluation of the solid state forms available to pharmaceutical new chemical entities. Understanding of the solid state forms becomes more difficult when individual samples present as mixed forms, especially when it is not immediately recognized that the samples represent a mixture. In this study, TGA-DTA, in combination with light microscopy and powder X-ray diffraction, provided immediate evidence that samples represented mixed solid state forms. The initial assessment was made using as little as 5 mg of sample. Hygroscopicity challenges provided further proof for mixed forms. To make a definite assignment of the solid state forms present, isolation of pure phases of the suspected individual forms was necessary. Success of this testing strategy is illustrated using an example of mixed salt stoichiometry and mixed hydration states. A hierarchy is suggested for efficient isolation efforts when a complex mixture of solid state samples is present.


    Author Information:

    Redman-Furey, NL
    Principal Scientist, P&G Pharmaceuticals, Inc., Norwich, New York,

    Dicks, ML
    Principal Researcher, P&G Pharmaceuticals, Inc., Norwich, New York,

    Godlweski, J
    Principal Researcher, P&G Pharmaceuticals, Inc., Norwich, New York,

    Vaughn, DC
    Senior Researcher, P&G Pharmaceuticals, Inc., Norwich, New York,

    Collins, WJ
    Senior Researcher, P&G Pharmaceuticals, Inc., Norwich, New York,


    Stock #: JAI12792

    ISSN: 1546-962X

    DOI: 10.1520/JAI12792

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    Author
    Title The Role of TGA-DTA in the Initial Evaluation of the Solid State Forms for Pharmaceutical New Chemical Entities, Part 2: Evaluation of Mixed Forms
    Symposium Techniques in Thermal Analysis:Hyphenated Techniques, Thermal Analysis of the Surface, and Fast Rate, 2004-05-25
    Committee E37