Daniel Capon of Glass Technology Services on the trend to badge any perceived problem with glass used in packaging as delamination
Lamellae sample in suspension following prolonged, agressive attack on glass surface
There has been a clear trend to badge any perceived problem with glass used in pharmaceutical packaging as delamination, when in fact many resulted from other causes, some of which are potentially much simpler and cheaper to remedy.
“It is vital not to make generalisations, based on recent product recalls,” said Daniel Capon of independent experts Glass Technology Services Ltd (GTS).
According to Capon, glass containers remain the preferred choice for most medicinal products and risk can be mitigated and controlled to ensure both product quality and patient safety.
“Where I think the industry could be missing a trick is in not assuming delamination in the first instance, but instead analysing each appearance of flakes or particles to address the root cause,” Capon says.
Based on extensive experience of samples sent to GTS for delamination analysis, Capon says that often what looked like tiny glass fragments, flakes (lamellae) or deposits, were actually naturally occurring compounds that had precipitated out of solution and dissolved back into the solution by the time the sample reached the GTS laboratory, or were foreign bodies introduced during subsequent production and filling processes or by the end-user.
SEM image showing surface attack of flame worked region on vial sidewall
The true source of delamination in the case of borosilicate type 1 glass is flameworking of the glass that can cause boron to volatilise from the surface of the glass.
This process leaves behind a silica-rich surface layer that has a different thermal expansion to the bulk glass, which in turn can cause the surface to flake off when exposed to variances in temperature, for example.
In the case of soda-lime-silica type III glass, the term delamination is used to describe the effect that occurs due to constant attack of the glass surface from the liquids in the container, which leaches the alkaline components of the glass resulting in a more alkaline solution.
This increases the rate of attack until a skin of predominately silica is left on the glass surface, which can eventually detach and be seen as very thin shimmering particles within the solution.
SEM image showing bulk glass on vial sidewall without any sign of surface attack
This effect can even occur with glasses that have good durability were exposed to high or cyclic temperatures.
“Independent testing can provide essential information to demonstrate due diligence and compliance in the event of any litigation,” says Capon.
“It could also avoid costly product recalls. At the very least, it can ensure that you are focusing on solving the right problem,” he concludes.