Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2486144 | Journal of Pharmaceutical Sciences | 2011 | 10 Pages |
Abstract
The purpose of this study was to elucidate the effect of heat treatment on the miscibility of multiple concentrated solutes that mimic biopharmaceutical formulations in frozen solutions. The first heating thermal analysis of frozen solutions containing either a lowâmolecularâweight saccharide (e.g., sucrose, trehalose, and glucose) or a polymer (e.g., polyvinylpyrrolidone and dextran) and their mixtures from â70°C showed a single transition at glass transition temperature of maximally freezeâconcentrated solution (Tgâ²) that indicated mixing of the freezeâconcentrated multiple solutes. The heat treatment of singleâsolute and various polymerârich mixture frozen solutions at temperatures far above their Tgâ² induced additional ice crystallization that shifted the transitions upward in the following scan. Contrarily, the heat treatment of frozen disaccharideârich solutions induced twoâstep heat flow changes (Tgâ² splitting) that suggested separation of the solutes into multiple concentrated noncrystalline phases, different in the solute compositions. The extent of the Tgâ² splitting depended on the heat treatment temperature and time. Twoâstep glass transition was observed in some sucrose and dextran mixture solids, lyophilized after the heat treatment. Increasing mobility of solute molecules during the heat treatment should allow spatial reordering of some concentrated solute mixtures into thermodynamically favorable multiple phases.
Keywords
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Authors
KenâIchi Izutsu, Chikako Yomota, Toru Kawanishi,