Defects on the glass surface are a major cause of occasional breakage of the primary packaging container during fill and finish or transport. Scratches and cracks are only some of the weak points that can occur to container breakage when mechanical load is applied. With EVERIC?, SCHOTT is introducing a modular concept for different vial features to improve the overall processing performance so that the vials run smoothly on the high-speed bulk production lines. Additionally, it addresses the market trend to individualizing primary packaging container to the requirements of different drug formulations. SCHOTT has run a series of tests to find out more about the glass vials’ tendency to break. The results show a significant increase of vial strength by a factor of 4. At the same time, the tests result in a decrease of cosmetic defects of 95%. 

The EVERIC? concept

The new vial concept offers pharmaceutical companies a choice of features that can be flexibly combined addressing individual needs and requirements in the context of the containers itself and the efficient processing of such a primary packaging. The three respective features are introduced to market by EVERIC? “pure”, “strong” and “smooth”.

Many pharma companies worldwide already use the first feature, EVERIC? pure. It addresses the fact that the bottom-near area of vials sometimes tend to have an inhomogeneous surface after the hot forming process, which can lead to delamination or other leached glass elements. This tendency is higher for highly sensitive biotech drugs as they mostly come with a low-filling volume and have an increased risk of reduced drug stability. Dedicated production lines for EVERIC? pure vials with much tighter in-process control ensures a homogenous wall near the bottom area, the so-called heel zone, and therefore bringing delamination under control. Tests have shown a significant reduction of 68% of sodium at a filling volume of 0.5mL in an EVERIC? pure vial compared to a standard vial.

EVERIC? strong and smooth addresses the topic of glass breakage avoidance and efficient processing. The “strong” feature covers an improved geometry within ISO tolerances for these vials. Besides improving the forming process in terms of axial load and side compression, it also leads to an elimination of inherent stress in the glass. Furthermore, the process is optimized at all handling and contact points to offer a flawless glass quality—from to tube to final containers. The “smooth” feature offers an outer coating that additionally protects the outer glass surface from the creation of flaws, (e.g., scratches during the entire process during converting or fill and finish operations. Markus Heinz from Bosch Packaging Technology sees a major benefit in the outer coating: “Scratch resistant vials cause less cosmetic defects and decrease significantly the false reject rate in inspection at later stages of the production process.” The outer coating also creates a low-friction outer glass surface for a smooth container flow in production lines to prevent climbing or sticking and to reduce particles in filling lines.

Vials put to the endurance test

SCHOTT subjects the features “strong” and “smooth” to a series of tests under real conditions. Here, 2R EVERIC? vials are tested against 2R vials of the highest quality standard currently available from SCHOTT. The tests are undertaken with samples from a trial run of more than 100,000 vials for statistical reasons, once their initial state and after the vials had passed the complete filling process. All vials are filled with WFI (water for injection), sealed, and crimped. Afterwards, the vials are subjected to various tests according to ISO specifications: a burst test (i.e., filling of the vials until they burst), and a strength test involving axial and side pressure in which the vials are subjected to pressure from above or the side. The goal is to test the extent to which the improved geometry and the outer coating makes the vials more resistant to mechanical loads during the filling process. In order to prevent previous damages on the vials, the samples have been delivered in special trays to avoid glass-to-glass contact.

Since only statistical statements can be made within the framework of strength analyses of glass, the results of the tests were presented using Weibull distributions. In Figures 1-–3, the X-axis represents the strength of the vial type, while the Y-axis shows the probability of glass breakage occurring. The results concentrate on the 10% quantile of each distribution curve.