Different or the same? exploring the physicochemical properties and molecular mobility of celecoxib amorphous forms

Mengwei Wang, Olivia Aalling-Frederiksen, Anders Madsen, Kirsten M.Ø. Jensen, Mads R.V. Jørgensen, Junbo Gong*, Thomas Rades*, Inês C.B. Martins*

*Corresponding author for this work

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Abstract

The influence of different preparation methods on the physicochemical properties of amorphous solid forms have gained considerable attention, especially with recent publications on pharmaceutical polyamorphism. In the present study, we have investigated the possible occurrence of polyamorphism in the drug celecoxib (CEL) by investigating the thermal behavior, morphology, structure, molecular mobility and physical stability of amorphous CEL obtained by quench-cooling (QC), ball milling (BM) and spray drying (SD). Similar glass transition temperatures but different recrystallization behaviors were observed for CEL-QC, CEL-BM and CEL-SD using modulated differential scanning calorimetry analysis. A correlation between the different recrystallization behaviors of the three CEL amorphous forms and the respective distinct powder morphologies, was also found. Molecular dynamics simulations however, reveal that CEL presents similar molecular conformational distributions when subjected to QC and SD. Moreover, the obtained molecular conformational distributions of CEL are different from the ones found in its crystal structure and also from the ones found in the lowest-energy structure obtained by quantum mechanical calculations. The type and strength of CEL hydrogen bond interactions found in CEL-QC and CEL-SD systems are almost identical, though different from the ones presented in the crystal structure. Pair distribution function analyses and isothermal microcalorimetry show similar local structures and structural relaxation times, respectively, for CEL-QC, CEL-BM and CEL-SD. The present work shows that not only similar physicochemical properties (glass transition temperature, and structural relaxation time), but also similar molecular conformational distributions were observed for all prepared CEL amorphous systems. Hence, despite their different recrystallization behaviors, the three amorphous forms of CEL did not show any signs of polyamorphism.

Original languageEnglish
Article number124470
JournalInternational Journal of Pharmaceutics
Volume661
Number of pages9
ISSN0378-5173
DOIs
Publication statusPublished - 2024

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Publisher Copyright:
© 2024 The Authors

Keywords

  • Celecoxib
  • Glass transition temperature
  • Molecular dynamics simulations
  • Pair distribution function
  • Structural relaxation time

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