STP1466

    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

    Published: Jan 2007


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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.

    Keywords:

    TGA, DTA, hydrate, thermal analysis, hygroscopicity, pharmaceutical, Risedronate


    Author Information:

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

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

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

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

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


    Paper ID: STP45223S

    Committee/Subcommittee: E37.01

    DOI: 10.1520/STP45223S


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