Spatial Distribution of Trehalose Dihydrate Crystallization in Tablets by X-ray Diffractometry.

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Analytical Chemistry

Background:

• Amorphous anhydrous trehalose tablets can crystallize into trehalose dihydrate under specific humidity conditions.
• Understanding the spatial distribution of drug crystallization within tablets is crucial for stability assessment and formulation development.

Purpose of the Study:

• To evaluate and compare two distinct methods for profiling the spatial distribution of drug crystallization within trehalose tablets as a function of depth.
• To assess the advantages and limitations of each method for characterizing crystallization gradients.

Main Methods:

• Glancing angle X-ray diffractometry (GAXRD) was employed, modulating X-ray penetration depth via incident angle to analyze crystallization as a function of depth.
• Split tablet analysis involved sectioning tablets and analyzing 36 regions from the surface to the midplane using X-ray diffraction (XRD).
• Synchrotron radiation in transmission mode was used to validate average crystallization levels across the entire tablet.

Main Results:

• Both GAXRD and split tablet analysis generally agreed on the extent of crystallization with depth.
• GAXRD detected crystallization up to approximately 650 μm and exhibited a surface bias.
• Split tablet analysis, though destructive, provided comprehensive and unbiased depth-profiling data.

Conclusions:

• GAXRD is a non-destructive technique suitable for repeated measurements during stability studies, offering surface-biased depth information.
• Split tablet analysis provides more complete, unbiased depth profiling but is a destructive method.
• The choice of method depends on the specific requirements for stability assessment and the need for destructive versus non-destructive analysis.