Thermal investigation on hydrated co-amorphous systems of nicotinamide and prilocaine

Xiaoyue Xu, Thomas Rades, Holger Grohganz*

*Corresponding author for this work

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Abstract

It is generally recognized that water, acting as a plasticizer, increases molecular mobility, leading to a decrease of the glass transition temperature (Tg) in amorphous systems. However, an anti-plasticizing effect of water was recently observed on prilocaine (PRL). This effect might be used in co-amorphous systems to moderate the plasticizing effect of water. Nicotinamide (NIC) can form co-amorphous systems with PRL. In order to investigate the effect of water on these co-amorphous systems, the Tgs and molecular mobility of hydrated co-amorphous NIC-PRL systems were compared with those of the respective anhydrous systems. Molecular mobility was estimated by considering the enthalpic recovery at the Tg using the Kohlrausch-Williams-Watts (KWW) equation. At molar ratios of NIC above 0.2, a plasticizing effect of water on co-amorphous NIC-PRL systems was observed with increasing the NIC concentration. In contrast, at molar ratios of NIC of 0.2 and below, water had an anti-plasticizing effect on the co-amorphous NIC-PRL systems, with increased Tgs and reduced mobility upon hydration.

Original languageEnglish
JournalEuropean Journal of Pharmaceutics and Biopharmaceutics
Volume186
Pages (from-to)1-6
ISSN0939-6411
DOIs
Publication statusPublished - 2023

Bibliographical note

Funding Information:
Xiaoyue Xu acknowledges the China Scholarship Council (Grant 202008420212) for financial support.

Publisher Copyright:
© 2023 The Author(s)

Keywords

  • Anti-plasticizing effect of water
  • Co-amorphous
  • Glass transition
  • Molecular mobility
  • Prilocaine-nicotinamide

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