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Published on: August 9, 2022
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The effect of processing on the surface physical stability of amorphous solid dispersions
Ziyi Yang1, Kathrin Nollenberger2, Jessica Albers2
1School of Pharmacy, University of East Anglia, Norwich, UK; UCL School of Pharmacy, London, UK.
Summary
Spin coating enhances surface physical stability of amorphous molecular dispersions more than hot melt extrusion. This is due to rapid solvent evaporation, preventing surface crystallization and drug enrichment.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
Background:
- Amorphous molecular dispersions are crucial for drug delivery, but their physical stability, especially at the surface, is a challenge.
- Surface crystallization can negatively impact drug product performance and shelf-life.
Purpose of the Study:
- To investigate the impact of processing methods on the surface crystallization of amorphous molecular dispersions.
- To elucidate the mechanisms behind processing-induced surface physical stability differences.
Main Methods:
- Amorphous molecular dispersions of felodipine-EUDRAGIT® E PO were prepared using spin coating and hot melt extrusion (HME).
- Samples were aged under controlled humidity and temperature, and characterized using powder X-ray diffraction (PXRD), ATR-FTIR, SEM, AFM, and localized thermal analysis.
Main Results:
- Hot melt extrusion (HME) samples with high drug loadings (50-90%) exhibited rapid surface crystallization upon storage.
- Spin-coated dispersions showed significantly higher surface physical stability compared to HME samples.
- Drug enrichment at the surface was observed in HME samples, correlating with surface crystallization.
Conclusions:
- Spin coating offers superior surface physical stability for amorphous molecular dispersions compared to HME.
- The enhanced stability from spin coating is attributed to increased apparent drug-polymer solubility and reduced molecular mobility from rapid solvent evaporation.
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