Instability, stabilization, and formulation of liquid protein pharmaceuticals.

Conformational constraints for amyloid fibrillation: the importance of being unfolded.

Protein aggregation and its inhibition in biopharmaceutics

https://imechanica.org/files/bromberg_temperature_responsive_gels.pdf

Temperature-responsive gels and thermogelling polymer matrices for protein and peptide delivery.

Bioabsorbable polymer scaffolds for tissue engineering capable of sustained growth factor delivery.

The stability of protein-based pharmaceuticals (e.g., insulin) is important for their production, storage, and delivery. To gain an understanding of insulin's aggregation mechanism in aqueous solutions, the effects of agitation rate, interfacial interactions, and insulin concentration on the overall aggregation rate were examined. Ultraviolet absorption spectroscopy, high-performance liquid chromatography, and quasielastic light scattering analyses were used to monitor the aggregation reaction and identify intermediate species. The reaction proceeded in two stages; insulin stability was enhanced at higher concentration. Mathematical modeling of proposed kinetic schemes was employed to identify possible reaction pathways and to explain greater stability at higher insulin concentration.

https://www.pnas.org/content/pnas/88/21/9377.full.pdf

Kinetics of insulin aggregation in aqueous solutions upon agitation in the presence of hydrophobic surfaces.

Undesirable aggregation of aqueous insulin solutions remains a serious obstacle in the development of alternative methods of diabetes therapy. We investigated the fundamental nature of the aggregation mechanism and proposed stabilization strategies based on a mathematical model for the reaction scheme. Insulin aggregation kinetics in the presence of solid-liquid and air-liquid interfaces were monitored using UV spectroscopy and quasielastic light scattering (QELS). Experimental observations were consistent with our model of monomer denaturation at hydrophobic surfaces followed by the formation of stable intermediate species which facilitated subsequent macroaggregation. The model was used to predict qualitative trends in insulin aggregation behavior, to propose stabilization strategies, and to elucidate mechanisms of stabilization. In the absence of additives, insulin solutions aggregated completely (more than 95% of the soluble protein lost) within 24 h; with sugar-based nonionic detergents, no detectable loss occurred for more than 6 weeks.

Victoria Sluzky

Papers

Kinetics of insulin aggregation in aqueous solutions upon agitation in the presence of hydrophobic surfaces.

Mechanism of insulin aggregation and stabilization in agitated aqueous solutions

The Pharmaceutical Development of Insulin: Historical Perspectives and Future Directions