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Qualitative in situ analysis of multiple solid-state forms using spectroscopy and partial least squares discriminant
Karin Kogermann1, Jaakko Aaltonen, Clare J Strachan
1Division of Pharmaceutical Technology, University of Helsinki, Helsinki, Finland.
Journal of Pharmaceutical Sciences
|January 27, 2007
Summary
This study reveals multiple solid-state forms during drug dehydration using in situ spectroscopy. Near-infrared (NIR) and Raman spectroscopy effectively differentiate these forms, aiding pharmaceutical development.
Area of Science:
- Solid-state chemistry
- Pharmaceutical analysis
- Spectroscopic techniques
Background:
- Understanding solid-state transformations is crucial for drug stability and bioavailability.
- Isothermal dehydration of hydrates can lead to complex phase transitions.
- Accurate characterization of these forms is essential for pharmaceutical development.
Purpose of the Study:
- To reveal multiple solid-state forms appearing during isothermal dehydration of hydrates.
- To evaluate the utility of in situ spectroscopy for monitoring dehydration processes.
- To demonstrate the capability of multivariate modeling for differentiating solid-state modifications.
Main Methods:
- In situ near-infrared (NIR) and Raman spectroscopy combined with multivariate modeling (PLS-DA).
- Hot-stage analysis at varying temperatures.
- Reference methods included XRPD, DSC, TGA, and Karl Fisher titration.
Main Results:
- Multiple solid-state forms were identified during the isothermal dehydration of piroxicam and carbamazepine (CBZ) hydrates.
- Partial Least Squares Discriminant Analysis (PLS-DA) models successfully differentiated between various solid-state modifications based on spectral data.
- Hydrates, like CBZ dihydrate, can exhibit several intermediate solid-state forms during dehydration.
Conclusions:
- In situ spectroscopic analysis is a powerful tool for monitoring dehydration and identifying associated solid-state forms.
- Complementary NIR and Raman spectroscopy, coupled with multivariate analysis, enable qualitative assessment of phase transitions.
- Understanding intermediate forms is critical for accurate quantitative analysis in pharmaceutical solid-state characterization.
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