Moisture-Induced Aggregation of Lyophilized Insulin
- 1 January 1994
- journal article
- Published by Springer Science and Business Media LLC in Pharmaceutical Research
- Vol. 11 (1), 21-29
- https://doi.org/10.1023/a:1018981208076
Abstract
A critical problem in the storage and delivery of pharmaceutical proteins is aggregation in the solid state induced by elevated temperature and moisture. These conditions are particularly relevant for studies of protein stability during accelerated storage or for proteins loaded in polymeric delivery devices in vivo. In the present investigation, we have found that, when exposed to an environment simulating these conditions, lyophilized insulin undergoes both covalent and noncovalent aggregation. The covalent process has been elucidated to be intermolecular thiol-catalyzed disulfide interchange following β-elimination of an intact disulfide bridge in the insulin molecule. This process is accelerated by increasing the temperature and water content of the insulin powder or by performing lyophilization and/or dissolution of insulin in alkaline media. The aggregation can be ameliorated by the presence of Cu 2+ , which presumably catalyzes the oxidization of free thiols. The water sorption isotherm for insulin reveals that the extent of aggregation directly correlates with the water uptake by the lyophilized insulin powder, thus pointing to the critical role of protein conformational mobility in the aggregation process.Keywords
This publication has 15 references indexed in Scilit:
- Pharmaceutics of protein drugs.1992
- Chemical stability of insulin. 3. Influence of excipients, formulation, and pH.1992
- Chemical stability of insulin. 4. Mechanisms and kinetics of chemical transformations in pharmaceutical formulation.1992
- Determining the optimum residual moisture in lyophilized protein pharmaceuticals.1992
- Kinetics of insulin aggregation in aqueous solutions upon agitation in the presence of hydrophobic surfaces.Proceedings of the National Academy of Sciences, 1991
- Enzyme thermoinactivation in anhydrous organic solventsBiotechnology & Bioengineering, 1991
- Moisture‐induced aggregation of lyophilized proteins in the solid stateBiotechnology & Bioengineering, 1991
- Controlled Release of Insulin From Polymer Matrices: Control of Diabetes in RatsDiabetes, 1986
- Generation of an acid-stable and protein-bound persulfide-like residue in alkali or sulfhydryl-treated insulin by a mechanism consonant with the .beta.-elimination hypothesis of disulfide bond lysisBiochemistry, 1983
- [8] Reassessment of Ellman's reagentMethods in enzymology, 1983