Formation of subvisible particles in commercial insulin formulations

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2022-08, Vol.216, p.112566-112566, Article 112566
• Main Authors: Silva-Jr, Hamilton, Araújo, Talita S., da Silva Almeida, Marcius, Scapin, Sandra M.N., Lima, Luís Maurício T.R.
• Format: Article
• Language: English
• Subjects: Aggregation; Insulin; Stability; Subvisible particles
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2022.112566

The conformation and assembly of insulin are sensitive to physical and chemical variables. Insulin can misfold and form both amorphous and amyloid aggregates. Localized cutaneous amyloidosis due to insulin usage has been reported, and question remains regarding its stability in the original flasks due to storage and handling. Here we report the evaluation of the formation of aggregates in insulin formulations upon once-weekly handling and storage of the in-use cartridges at 4 °C or 37 °C for 5 weeks. Electrospray ionization mass spectrometry showed no obvious chemical decomposition. No major changes in oligomeric distribution were observed by size-exclusion chromatography. Dynamic light scattering allowed the identification of particles with high hydrodynamic radius formed during storage at 4 °C and 37 °C. Transmission electron microscopy analysis revealed the formation of amorphous material, with no clear evidence for amyloid material up to 28 days of incubation. These data support evidences for the formation of subvisible and submicrometer amorphous particulate matter in insulin formulations shortly upon use. [Display omitted] •Physical instability may compromise therapeutic effectiveness of biologicals.•Proteins may form amorphous or fibrillar particles with unsuitable effects.•Insulin formulations may form amorphous agglomerates upon handling.•Subvisible high molecular weight particles could be detected by light scattering.