The Glass Quality You Seek Does Exist

Everyday objects, such as a glass jar, a bottle or even a car window, tend to be made from an easy-to-melt glass composition that is fairly inexpensive to manufacture. As a result, the glass can have poor chemical durability – after all, you don’t need high chemical durability for soda. But this “everyday” glass is not suitable for pharmaceutical use. For a pharmaceutical product, impurities from the primary packaging can cause problems – such as contamination, degradation of the APIs, or even pH shifts. Glass for pharmaceutical use must have excellent chemical durability to keep the drug product stable for as long as possible. This durability can be achieved by increasing the aluminum oxide in the glass or by keeping the silica content of the glass high.

Pharmaceutical filling lines process hundreds of vials a minute, creating glass-to-glass frictive contact that leads to scratches and breakage. It can also lead to small glass particles and cause down-time. The underlying cause of these challenges is that conventional borosilicate glass vials have a high coefficient of friction surface, increasing their predisposition to jam. In this situation the operators may have to intervene, increasing the potential for contamination (1).

Often, pharma manufacturers don’t realize that these problems can be reduced or avoided. Background glass particles, for example, are considered the “norm” since they are created as vials rub against one another on the filling line. When one pharma company switched from borosilicate glass to Corning’s Valor^® Glass during a line trial, they assumed their particle monitoring equipment was broken because the particle counts in the filling environment dropped to such low levels. They hadn’t realized it was possible to reduce particle counts so much simply by changing the glass!

There are many glass suppliers who highlight the processes used to make the glass, and how, for example, they reduce the potential for defects. In many instances, the solutions only address one problem – one solution tackles delamination, another reduces extractables and leachables, and a third might focus on machinability. In contrast, Corning’s Valor Glass has been developed as a holistic glass solution that minimizes as many problems as possible – simultaneously.

To create Valor Glass, Corning’s R&D team took a Quality by Design approach. They identified the root causes of problems like delamination and breakage and used materials science to optimize the glass composition. For example, the root cause of delamination was traced to the evaporation and condensation of boron from borosilicate glass during the tube-to-vial converting process. The resulting boron-free composition of Valor Glass specifically eliminates delamination and gives the glass low extractable concentrations (2). The low friction external surface keeps it inherently strong and damage resistant, moves smoothly through manufacturing lines, and can reduce peak particle counts by up to 96 percent.

Quality advocates

The FDA has continued to raise concerns with the quality of conventional glass packaging through both advisory and other communications (3). Moreover, FDA has supported – through its Emerging Technology Program – advancement of new glass packaging technologies, like Valor Glass, with the potential to improve drug product quality. Traditionally, glass manufacturers have been seen as “just suppliers” to pharma manufacturers, with prices based on the cost of materials and manufacturing process. But there have been some negative consequences related to glass quality issues, such as drug recalls resulting from delamination, or from glass particles in the drug container. Poor filling line efficiency due to jamming vials or breakages can also add to manufacturing costs. These issues can be reduced with the right glass containers. A product like Valor Glass may cost a little more than conventional borosilicate glass, but it will improve manufacturing by resulting in fewer problems that could lead to delays, drug shortage or potential recalls – a win for both manufacturers and patients.

At Corning, solving tough customer problems is what we do. We do our best work when we have the opportunity to partner for innovation.