Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8994340 | Journal of Pharmaceutical Sciences | 2005 | 7 Pages |
Abstract
Isothermal calorimetry and lowâfield nuclear magnetic resonance were used to measure crystallization of glycine during annealing of glycine/sucrose mixtures, a commonlyâused excipient system for freezeâdried proteins. Kinetics of crystallization of glycine were consistent between the two methods, although the NMR method was significantly more sensitive. By the calorimetric method used here, sensitivity was lost when the total solute concentration was below about 20% (w/v) and the relative glycine concentration below about 35% of the total solids. By the NMR method, total solute concentrations as low as 5% (w/v) could be studied. When the relative concentration of glycine is below about 30% of total solids, the time course of crystallization becomes excessively long for practical freezeâdrying applications. A good fit of the crystallization data was obtained with the Johnson-Mehl-Avrami (JMA) equation. The Avrami exponent of 2.5 is consistent with diffusionâlimited spherulitic growth of glycine. © 2005 WileyâLiss, Inc. and the American Pharmacists Association J Pharm Sci 94:625-631, 2005
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Authors
Xuhong Li, Steven L. Nail,