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Freeze-concentration separates proteins and polymer excipients into different amorphous phases
1National Institute of Health Sciences, Setagaya, Tokyo, Japan. izutsu@nihs.go.jp
Pharmaceutical Research
|January 6, 2001
Summary
Protein and polymer excipient miscibility in frozen solutions and freeze-dried solids was studied. Freeze-concentration can separate protein-polymer mixtures, impacting formulation design.
Area of Science:
- Pharmaceutical Sciences
- Biophysical Chemistry
Background:
- Protein formulations are crucial for drug delivery.
- Understanding excipient interactions is key to stabilizing proteins.
Purpose of the Study:
- To investigate the miscibility of proteins and polymer excipients in frozen solutions and freeze-dried solids.
- To model protein formulation behavior under different conditions.
Main Methods:
- Differential scanning calorimetry (DSC) was used to analyze thermal profiles.
- Miscibility was assessed using glass transition temperatures (Tg' and Tg) of freeze-concentrated and freeze-dried states.
Main Results:
- Protein-polymer combinations were generally miscible in frozen solutions, with miscibility dependent on protein ratio.
- Salts influenced miscibility, causing phase separation in some protein-polyvinylpyrrolidone (PVP) mixtures.
- Results from frozen solutions were consistent with those from freeze-dried solids.
Conclusions:
- Freeze-concentration can lead to phase separation of protein-polymer mixtures.
- Controlling polymer miscibility is essential for effective protein formulation design.