Delamination has existed as a fundamental glass challenge for pharmaceutical glass vial manufacturers for decades.
Corning leveraged over 167-years of glass and material science expertise to launch a root-cause analysis to study the issue of glass delamination. The result?
We’ve eliminated the problem.
Comparison of converting process for pharmaceutical primary glass packaging. Sodium-borate evaporates out of borosilicate glass container during converting, producing heterogeneous areas that are predisposed to delaminate. Corning Valor® Glass eliminates glass delamination in pharmaceutical vials. Sodium-borate evaporation is not possible. As a result, Valor Glass containers have a uniform, chemically-durable drug contacting surface.
Watch the Converting of Pharmaceutical Primary Packaging video below.
While boron, a volatile element, is the root cause for delamination – the converting process also impacts a container’s chemical durability. During the converting process, specifically the step where the glass cane is parted (or separated) into two containers, the flame releases the boron from the glass network. Boron-containing compounds move around and evaporate as gas out of the glass network largely in the heel region of the vial.
Like a charged helium balloon sticks to a wall or object, the boron particles adhere to cool regions in the side-walls and heel (bottom) of the vial. A composition already rich in boron is now converted into its final format, with deposits that are richer in boron and sodium than the intended composition. This alters the glass chemistry of the container’s drug-contact surface. These areas rich in sodium borate, are vulnerable to delamination and ultimately pose risk to pharmaceutical product quality.
There are four steps from the formation of a heterogeneity to delamination. Corning notes those steps include, 1) Formation of heterogeneity, 2) Leaching, 3) Swelling and 4) Spalling off a delaminated flake. Because Valor Glass has uniform surface chemistry and does not form boron-rich heterogeneities during converting, it will not delaminate.
Glass delamination – the appearance of visible flakes or glass lamellae – has contributed to regulatory recalls. Beyond patient risk, delamination can be costly for pharmaceutical manufacturers. A glass supplier for the pharmaceutical industry notes, “For the respective manufacturers, this seemingly minor occurrence can then have costly consequences. One, single recall can cost a pharma company $250M dollars1.”
Corning Valor® Glass is a boron-free glass packaged designed specifically for pharmaceutical use to eliminate delamination. Corning was able to maintain a glass network comprised of elements used in borosilicate vials, including silica and alumina while eliminating delamination. Valor Glass is converted using traditional processes.
In addition, Valor Glass offers improved overall extractable and leachable performance for parenteral packaging applications relative to comparable borosilicate containers. This means vaccine vial manufacturers see lower overall concentrations or quantities of elements extracting out of Valor Glass’ composition relative to borosilicate containers, reducing the risk of potential interactions between the container and the drug product, even for low-fill conditions.
Enhanced converting techniques do not solve delamination, especially for medium and large-size vials. These techniques, typically, rely on an exhaust system to draw up volatile particles such as boron and sodium from the heel and carry them into different regions of the vial. As a result, heterogeneities can be found in all regions of the vial, not centrally located in only in the heel. The risk of delamination still exists and is not eliminated using enhanced techniques.
Read more about this topic at the links below.
For more information on Valor Glass or to receive a product overview from an expert, contact us at: pharma@corning.com.
1. Schott, “A new dimension of safety” (2019). Available at: https://www.us.schott.com/innovation/vials/
