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Crystallization Inhibition and Solid-State Stability in High Drug Loaded Amorphous Drug-Polymer Dispersions Above the
Sichen Song1,2, Ronald A Siegel3,4
1Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, 55455, USA.
Amorphous solid dispersions (ASDs) improve drug solubility. Polymer concentration relative to overlap concentration (c*) dictates drug crystallization, with higher concentrations preventing it for better oral bioavailability.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
Background:
- Amorphous solid dispersions (ASDs) enhance oral bioavailability of poorly soluble drugs.
- Understanding polymer-drug interactions in ASDs is crucial for formulation development.
Purpose of the Study:
- To review the role of polymer concentration, specifically overlap concentration (c*), in controlling drug crystallization in high drug-loaded ASDs.
- To provide a mechanistic framework for rational polymer selection in ASD formulation.
Main Methods:
- Review of recent research on polymer concentration effects in ASDs.
- Analysis of the relationship between overlap concentration (c*) and drug crystallization kinetics.
- Case studies across diverse drug-polymer systems.
Main Results:
- Below c*, polymer-free drug domains promote crystallization.
- Above c*, a homogeneous polymer matrix suppresses crystallization by delaying nucleation.
- This framework applies broadly but has limitations with high molecular weight polymers.
Conclusions:
- The overlap concentration (c*) is a critical parameter for controlling crystallization in high drug-loaded ASDs.
- A c*-guided rheological approach enables rational polymer selection and optimization for ASD formulations.
- This strategy is key for developing reduced-volume, high-efficacy drug products.
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