Isomalt and its diastereomer mixtures as stabilizing excipients with freeze-dried lactate dehydrogenase

Abstract

The purpose of this research was to study isomalt as a protein-stabilizing excipient with lactate dehydrogenase (LDH) during freeze-drying and subsequent storage and compare it to sucrose, a standard freeze-drying excipient. Four different diastereomer mixtures of isomalt were studied. The stability of the protein was studied with a spectrophotometric enzyme activity test and circular dichroism after freeze-drying and after 21 days of storage at 16% RH. Physical stability was analyzed with differential scanning calorimetry and Karl Fischer titration. Statistical analysis was utilized in result analysis. LDH activity was almost completely retained after freeze-drying with sucrose; whereas samples stabilized with isomalt diastereomer mixtures had a considerably lower protein activity. During storage the sucrose-containing samples lost most of their enzymatic activity, while the isomalt mixtures retained the protein activity better. In all cases changes to protein secondary structure were observed. Isomalt diastereomer mixtures have some potential as protein-stabilizing excipients during freeze-drying and subsequent storage. Isomalt stabilized LDH moderately during freeze-drying; however it performed better during storage. Future studies with other proteins are required to evaluate more generally whether isomalt would be a suitable excipient for pharmaceutical freeze-dried protein formulations.

Protecting Lyophilized Escherichia coli Adenylate Kinase

“…In one study, less excipient was needed to preserve the activity of catalase than to preserve its native structure . Isomalt and sucrose preserve the secondary structure of lactate dehydrogenase equally but activity differently . In a study of recombinant human factor XIII, native structure preservation during lyophilization was important for storage stability at elevated temperatures and recovery of native structure upon rehydration, but this relationship did not always reflect the activity .…”

“…Knowledge of dry protein stability under heat stress is important for developing better formulations and storage requirements . As in other studies, ,,− additives protect differently after lyophilization compared to lyophilization plus heat. Protection of AdK activity after heating depends on the additive (Figure ).…”

“…87 Isomalt and sucrose preserve the secondary structure of lactate dehydrogenase equally but activity differently. 77 In a study of recombinant human factor XIII, native structure preservation during lyophilization was important for storage stability at elevated temperatures and recovery of native structure upon rehydration, but this relationship did not always reflect the activity. 88 Structural maintenance in the dry state is beneficial but not the sole indicator of functional protection after rehydration.…”

Amorphous Sugar Materials as Sustainable and Scalable Alternatives for Rigid, Short-Term-Use Products

“…While sugars are the most abundant small molecules sourced from biomass, their use in materials has been limited to minority components as additives and excipients or as feedstock for chemical synthesis of polymers. ,− In some instances, sugars have been manipulated as a material for sacrificial molds, shattering objects, and edible food coatings or packaging, which specifically target the brittle or water-soluble nature of pure sugar. − The combination of sugars and additives to create robust (i.e., not fragile) materials has been largely unexplored. Herein, we introduce this type of material, where shaped objects can be made quickly via injection molding (just like plastics) and where the materials are designed to withstand transportation, storage, and use in commodity applications rather than as ephemeral structures or edible products.…”