Polymorph characterization of active pharmaceutical ingredients (APIs) using low-frequency Raman spectroscopy

Area of Science:

• Materials Science
• Analytical Chemistry
• Pharmaceutical Science

Background:

• Polymorph characterization is crucial in the pharmaceutical industry for ensuring drug efficacy and safety.
• Traditional vibrational spectroscopy (FT-MIR, FT-NIR, Raman) uses high-frequency molecular vibrations, indirectly probing solid-state forms.
• Low-frequency vibrational spectroscopy directly probes lattice vibrations, offering potential for more direct analysis of intermolecular interactions.

Purpose of the Study:

• To demonstrate the utility of low-frequency Raman spectroscopy for the polymorphic characterization of active pharmaceutical ingredients (APIs).
• To highlight the advantages of low-frequency Raman spectroscopy over existing techniques for solid-state analysis.

Main Methods:

• Utilized recent advances in filter technology for single-stage spectrographs to acquire high-quality low-frequency Raman spectra (200-10 cm(-1)).
• Applied low-frequency Raman spectroscopy to polymorphic characterization of APIs.

Main Results:

• Low-frequency Raman spectroscopy provides intense, information-rich spectral bands.
• This technique shows potential for discriminating among different crystalline forms of APIs.
• The method offers benefits such as ease of sampling compared to existing techniques.

Conclusions:

• Low-frequency Raman spectroscopy is a promising technique for the polymorphic characterization of APIs.
• Further research is needed to fully understand the relationship between crystalline structure and low-frequency vibrational spectra for broader adoption.