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Related Experiment Videos

Solid state characterization of dehydroepiandrosterone

L C Chang1, M R Caira, J K Guillory

  • 1College of Pharmacy, University of Iowa, Iowa City 52242, USA.

Journal of Pharmaceutical Sciences
|October 1, 1995
PubMed
Summary

This study characterized seven solid forms of a compound, revealing their stability and dissolution properties. Form I is the most stable polymorph, but all forms convert to the stable monohydrate (form S2) under humid conditions.

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Area of Science:

  • Solid-state chemistry
  • Materials science
  • Pharmaceutical sciences

Background:

  • Understanding the solid-state properties of active pharmaceutical ingredients is crucial for drug development.
  • Polymorphism and solvate formation significantly impact a compound's physical and chemical behavior.

Purpose of the Study:

  • To isolate and characterize various solid forms of a compound.
  • To determine the thermodynamic stability and dissolution rates of different polymorphs and solvates.
  • To investigate phase transformations and their implications for formulation.

Main Methods:

  • X-ray powder diffractometry (XRPD) for structural identification.
  • Differential scanning calorimetry (DSC) and hot stage microscopy for thermal analysis.

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  • Solution calorimetry and dissolution rate measurements for thermodynamic and kinetic studies.

    • Main Results:

    • Seven solid forms were identified: three polymorphs (I-III), one monohydrate (S2), and three new solvates (S1, S3, S4).
    • Polymorphs I-III exhibit a monotropic relationship with decreasing stability: I > II > III.
    • Only forms I and S4 showed reproducible DSC thermograms; others underwent phase transformations.
    • All forms converted to the stable monohydrate (S2) during dissolution studies, indicating sensitivity to moisture.

    Conclusions:

    • The stable form I has a higher dissolution rate than metastable forms II and III.
    • Moisture control is critical in solid formulations to prevent conversion to the stable monohydrate (S2).
    • XRPD is effective for purity determination, detecting contaminants down to 5%.