Concentration and Chemical Stability of Commercially Available Insulins: A High-Resolution Mass Spectrometry Study

Adequacy of insulin concentration in commercially available insulin formulations has recently been challenged. We therefore repeatedly evaluated insulin content and stability of 58 insulin vials containing 5 different insulin formulations (human insulin, standard/faster-acting insulin aspart, insulin lispro, and insulin glargine) over a period of 85 days. High-resolution mass spectrometry was used to quantify intact monomeric insulin in glass vials and plastic pump cartridges exposed to three different temperatures (4°C, 22°C, 37°C), simulating real-life conditions. In all cases, measured insulin concentration was in accordance with FDA and European Medicines Agency (EMA) requirements without evidence of chemical instability.