Chemical analysis of solid-state irradiated human insulin.
OBJECTIVE
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.


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.


CONCLUSIONS
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
Hélène
H
Laboratory of Chemical and Physicochemical Analysis of Drugs (CHAM), Université Catholique de Louvain, CHAM 72.30, Avenue E. Mounier, 72, B- 1200, Brussels, Belgium. helene.terryn@cham.ucl.ac.be
Vanhelleputte
Jean-Paul
JP
Maquille
Aubert
A
Tilquin
Bernard
B
D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D005720:Gamma Rays; D008401:Gas Chromatography-Mass Spectrometry; D007004:Hypoglycemic Agents / Q000032:analysis* / Q000528:radiation effects*; D007328:Insulin / Q000032:analysis* / Q000528:radiation effects*; D008968:Molecular Conformation; D008970:Molecular Weight; D019265:Spectroscopy, Near-Infrared; D014835:Volatilization
D007004:Hypoglycemic Agents; D007328:Insulin