PURPOSE: To study the chemical modifications induced upon irradiation of solid human insulin at radiosterilization doses and investigate the influence of the absorbed dose on radiolysis. MATERIALS AND METHODS: Volatile radiolytic products were monitored by gas chromatography coupled with mass spectrometry (GC-MS) and non-volatile products by two different high performance liquid chromatography (HPLC) methods: the formation of higher molecular weight proteins was assessed by size exclusion liquid chromatography whereas assays for related compounds and chemical potency tests were carried out using reverse-phase HPLC-UV. Conformational changes were investigated by measurements of circular dichroism. RESULTS: After gamma irradiation at 10 kGy, the recovery of insulin was 96.8%; higher molecular weight proteins accounted for 0.35% (relative peak area) and other related compounds (including A21 desamido insulin) represented 1.29%. No major structural changes and no volatile radiolytic compounds were detected. CONCLUSION: Human insulin samples irradiated in the solid-state at 10 kGy (gamma rays) and 14 kGy (electron-beam) meet the European Pharmacopoeia requirements and can be considered as quite stable towards radiation from a chemical analysis viewpoint.
Terryn, H., Vanhelleputte, J.-P., Maquille, A., & Tilquin, B. (2006). Chemical analysis of solid-state irradiated human insulin. Pharmaceutical Research, 23(9), 2141-2148. https://doi.org/10.1007/s11095-006-9053-y (Original work published 2006)