Transformations between Co-Amorphous and Co-Crystal Systems and Their Influence on the Formation and Physical Stability of Co-Amorphous Systems

Wenqi Wu, Yixuan Wang, Korbinian Löbmann, Holger Grohganz, Thomas Rades*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

49 Citations (Scopus)

Abstract

The formation of co-amorphous and co-crystal systems are attractive formulation strategies for poorly water-soluble drugs. Intermolecular interactions between the drug and the coformer(s) play an important role in the formation of both systems, making the investigation of transformations between the two systems specifically interesting. The aim of this study thus was to investigate the transformation between the two systems and its influence on the formation and physical stability of co-amorphous systems. Carbamazepine (CBZ) along with benzoic acid, maleic acid, succinic acid, tartaric acid, saccharin, and nicotinamide were used as materials. First, CBZ-co-former co-crystals were prepared. Then the co-crystals and CBZ-co-former physical mixtures were ball milled to investigate the possible co-amorphization process. The XRPD and DSC results showed that CBZ and coformers tended to maintain (co-crystals as the starting material) or form co-crystals (physical mixtures as the starting material), rather than to form co-amorphous systems. Next, co-amorphization from CBZ-co-former physical mixtures via quench cooling was studied. While co-amorphous systems were obtained, the physical stability of these was very low, and the samples recrystallized to either co-crystal forms or the individual components. In conclusion, a possible transformation between the two systems was confirmed, but the resulting co-amorphous systems were highly unstable.

Original languageEnglish
JournalMolecular Pharmaceutics
Volume16
Issue number3
Pages (from-to)1294-1304
Number of pages11
ISSN1543-8384
DOIs
Publication statusPublished - 4 Mar 2019

Keywords

  • co-amorphous systems
  • co-crystal systems
  • physical stability
  • recrystallization
  • transformation

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