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Amorphous-Amorphous Phase Separation in API/Polymer Formulations.

Christian Luebbert1, Fabian Huxoll2, Gabriele Sadowski3

  • 1TU Dortmund, Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Emil-Figge-Str. 70, D-44227 Dortmund, Germany. christian.luebbert@bci.tu-dortmund.de.

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Summary
This summary is machine-generated.

This study investigated drug crystallization and phase separation in polymer formulations. Amorphous-amorphous phase separation (APS) and recrystallization occurred with ibuprofen, while felodipine only recrystallized, with findings predicted by PC-SAFT modeling.

Keywords:
PLGAamorphous solid dispersionamorphous-amorphous phase separationphase behaviorpoorly water-soluble drugthermodynamic model

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Area of Science:

  • Pharmaceutical Science
  • Materials Science
  • Physical Chemistry

Background:

  • Long-term stability of poorly-soluble drug formulations in polymers is crucial for bioavailability.
  • Drug crystallization and amorphous-amorphous phase separation (APS) are common challenges in these formulations.
  • While drug crystallization is understood, APS remains poorly characterized.

Purpose of the Study:

  • To investigate the crystallization behavior, APS, and glass-transition temperatures of ibuprofen and felodipine in PLGA excipients.
  • To compare the stability of different drug-polymer systems.
  • To model and predict APS occurrence in these formulations.

Main Methods:

  • Hot-stage microscopy and Differential Scanning Calorimetry (DSC) were employed.
  • Formulations included ibuprofen and felodipine in poly(lactic-co-glycolic acid) (PLGA) with varying monomer ratios.
  • Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) was used for modeling.

Main Results:

  • Amorphous-amorphous phase separation (APS) and recrystallization were observed in ibuprofen/PLGA formulations.
  • Only recrystallization occurred in felodipine/PLGA formulations.
  • PC-SAFT modeling successfully predicted the occurrence of APS, aligning with experimental results.

Conclusions:

  • The study differentiates the stability behavior of ibuprofen and felodipine in PLGA matrices.
  • PC-SAFT is a valuable tool for predicting APS in drug-polymer formulations.
  • Understanding APS is critical for developing stable, effective poorly-soluble drug delivery systems.