Dealkalization of the internal surfaces of pharmaceutical glass vials

Pharmaceutical glass vials are affected by the “Specific Release” phenomenon, consisting in a leaching of alkali and alkaline earth elements from the glass matrix to the aqueous solutions. Since Pharmacopeias set specific release detection limits, various approaches have been developed to address this phenomenon: from the deposition of internal protective coatings to the application of chemical treatments to dealkalize the internal surface of glass vials. In this work we focus on the development of a new chemical treatment based on non-toxic liquid compounds, with the aim of addressing the drawbacks of the actually industrially used gas-based treatment, that include hazardous gases and toxic byproducts. This study evaluates different optimization conditions for the deposition of the liquid treatment, including application temperature, nozzle aperture time, and post-deposition annealing cycles. The leached elements from treated and untreated vials are quantified using titration, Inductively Coupled Plasma Mass Spectrometry and Inductively Coupled Plasma Optical Emission Spectroscopy. Additionally, Scanning Electron Microscopy and Atomic Force Microscopy are employed to examine the internal surfaces of the vials. We demonstrate that, by tuning the deposition parameters, alkali and alkaline elements in the release show a reduction of at least 90 % in treated vials as compared to untreated ones, falling below the Pharmacopeias set limits and well compared to the industrially gas-treated vials. Morphologically, gas-treated vials exhibit repeated pitting in the areas that came into contact with the treatment, a feature not observed in untreated or liquid-treated vials, indicating a characteristic effect of the treatment used.