PharmInd: Comparative Predictive Glass Delamination Study

Glass is by far the predominant material used for pharmaceutical containers especially because of the chemical inertness and the excellent container closure properties. Nevertheless, the interaction with the drug product can alter the interior glass surface and generate adverse effects. In this study, the chemical durability of 20 mL Type I tubular borosilicate glass, Type I moulded borosilicate glass, and Type II moulded soda lime glass vials are assessed based on the methodology recommended in USP <1660> with respect to ultrapure H2O and 15 % KCl filling solutions stored up to 48 weeks at 40 °C. The study design used can clearly distinguish and rank the extent of a chemical attack based on differences observed on the interior glass surface by stereomicroscope and SEM cross-section analysis, amount of glass elements leached into solution by ICP-OES, and pH shifts. The observed chemical durability differences are directly related to the 2 independent variables, a combination of the glass composition and glass manufacturing/processing conditions. While all 3 vial types behaved similarly when filled with ultrapure H2O, significant differences were found when the vials were filled with a more aggressive filling solution of 15 % KCl. In contrast to generally accepted industry views of moulded glass vials having higher chemical durability in general to filling solutions, the moulded glass containers were more severely attacked by the 15 % KCl than the tubular glass containers. This should be considered when selecting containers not alone for drugs with active ingredients but also for water-based diluents with more or fewer salt components. Finally, there is a need for USP <1660> to assess each filling solution/container combination as the results in this study show that generally accepted trends are not always followed.