Although glass retains its dominant market share as the traditional material for packaging pharmaceutical parenterals, plastic is also finding use as concerns about glass breakage and delamination and desire for increased functionality lead pharmaceutical companies to consider alternatives.
The biggest change in primary containers has been in Japan, where it is estimated that 60–70% of all prefilled syringes are plastic (1). Interest in plastic is also increasing in Europe and the US. “Recent surveys have placed interest in plastic at different levels, but it is West’s understanding that the majority of pharmaceutical and biopharmaceutical companies are at least considering plastic as an alternative to glass,” says Graham Reynolds, vice-president of marketing and innovation of Pharmaceutical Delivery Systems at West.
Although most use of plastics so far has been in syringes, a growing concern with glass vials is the issue of delamination. FDA has initiated several recalls in recent years due to the risk that glass particulates may enter a patient through drug products and has cautioned manufacturers about glass fragments in vials (2). Glass-vial suppliers have responded with coated vials and by developing analytical tests for delamination, notes Gary Waller, North American vice-president of sales and marketing for Schott Pharmaceutical Systems.
Another concern with glass vials and syringes is breakage, which can occur during production, transport, or use. “With the increasing use of devices as part of a combination product, a glass container may not be visible, resulting in concerns about breakage when a device is dropped and a tendency to err on the side of caution. For example, patient instructions may suggest an auto-injector should be discarded if dropped due to the risk of glass breakage,” notes Reynolds.
In prefillable syringes, residuals on glass components may cause problems with some biologics. For example, silicone oil on glass can cause formation of protein/silicone aggregates. Plastic syringes eliminate the need for silicone oil. In addition, plastic offers improved design flexibility and dimensional precision, which can be important for use with devices, such as a self-injection system or needle-safety system. “The inherent variability in the dimensions of glass can lead to challenges when designing a device because many devices put stress on glass products, particularly in the flange area, where breakage can occur,” says Reynolds. Plastic prefillable syringes can be designed with an integrated luer lock, which is a more robust design than attaching a separate luer-lock adapter to a glass syringe, adds Waller.
Polymers have some drawbacks, however. One is scratch sensitivity; scratches can impair camera inspection, says Waller. Polymers typically have inferior oxygen permeability compared to glass, which can be a concern for oxygen-sensitive drugs. Compared to the long history of glass in parenteral containers, the short history of polymers can be a disadvantage. In many cases, however, polymers have been tested to ensure biocompatibility and acceptability for some drugs and have been approved and marketed for packaging.
Polymers used commercially in containers for parenterals include cyclic olefin copolymer (COC) and cyclic olefin polymer (COP). COP is a transparent material with an impact strength twice as high as that of glass used in standard syringes, which makes it shock- and break-resistant, says Wolfgang Dirk, product manager of plastic parenteral vials at Gerresheimer. Gerresheimer’s Multishell vials, which won the German Packaging Award in the Retail Packaging category in November, 2011, have a three-layer structure of polyamide (PA) sandwiched between two COP layers. PA is a good oxygen barrier, and the multilayer structure reduces oxygen transmission by 40 times compared to that of a monolayer COP vial. Multiple layers also provide additional break resistance, notes the company.
Top Clean Packaging Group, whose Unicadose polypropylene vial was a finalist for the Best Sustainable Packaging award by CPhI in October 2012, says that it was designed to increase consumer convenience and safety for single-dose drugs by preventing breakage and by providing an easily distinguishable appearance. The vial can be customized using different colors and by printing directly on the individual vial.
“Glass has been around for many years and will continue to be a suitable material for drug containment for many years to come. However, as newer and more sophisticated drug products and delivery technologies are developed, containment systems must evolve,” predicts Reynolds. Suppliers conclude that, while polymers are now an option, each drug product and delivery system should be evaluated to determine what packaging material and form is most appropriate on a case-by-case basis.