In response to the need for higher manufacturing output, packaging consistency and increased validation scrutiny, packaging material suppliers have introduced new packaging formulations. This article examines the benefits of using peelable materials for the fabrication of flexible packaging for medical devices.
Access without contamination
Designers and developers of flexible packaging for medical devices must always have as their first consideration the establishment and maintenance of the sterile barrier for the device, from the point of manufacture and packaging of the product to point of use. However, another important consideration is package access to give the end user the ability to effectively remove the device from its package. The design of this feature should take into account the way the user will be employing the device, for example, whether the user is
These end user situations are different, but they all require easy and consistent delivery without contamination. Peelability is a logical access feature to avoid concerns with particulates that occur when tearing open the package or using other destructive opening methods. This article provides an overview of the peelable flexible packaging materials that are available to the package designer. It is worth bearing in mind that the traditional inertia in changing packaging formats within the medical device industry, which is driven by the regulatory requirements of validation, means that older material technologies are still being used when more effective new formulations are available.
The pace of development of disposable medical devices in the late 1970s and early 1980s led to increased demand for packaging alternatives. Packaging material suppliers, together with base material suppliers, endeavoured to develop structures to meet that burgeoning demand:
|Figure I: Typical peel strength, coated paper to film.|
As versatile as these coatings were, there were inherent problems that drove the development of the next generation of peelable technology. These problems included:
The next generation of coatings for porous substrates were aqueous-based EVA dispersions mainly applied by air knife and these addressed many of the concerns associated with the solvent based coatings. In addition, new polymer technology enabled increased porosity of the applied coating, and advances in coating control improved consistency and quality. Other coatings utilising a hot melt process also increased porosity while maintaining wide seal windows. Today, adhesive coated substrates are versatile options for the packaging designer to consider. They provide a wide seal window of approximately 30 °C, consistent visible seal transfer (turns bright white when peeled), and in some cases the possibility of constructing packages capable of being sterilised by EtO and gamma. However, recent testing in the company’s laboratories has shown that these coatings may not remain intact over time and could potentially lead to sterility breaches, although none have been widely reported to date.
The explosive growth of disposable medical devices attracted the attention of increasing numbers of flexible packaging material suppliers, many with a significant base of business in other markets such as food and consumer packaging. This meant that many advances in flexible materials such as film coextrusion and lamination were being marketed to the medical device industry. The new options now available to the packaging designer include:
There have been a considerable number of advancements in flexible packaging in the past 10 years, including the development of coextrusion technology; new polymers such as ultralow density PE, elastomers and plastomers with greatly enhanced performance characteristics; and improvements in packaging machinery design. These advances, combined with a greater focus on the specific needs of the medical device industry, have expanded the options available to the packaging designer as follows.
Naturally, the use of an uncoated top web, whether paper or Tyvek, requires additional heat to be transferred through the lidding material and into the specialised sealant layer within the film. For this reason, sealing temperatures are usually higher than with a coated material, as shown in Figure II.
|Figure II: Peel strength, uncoated paper to film.|
Help with validation
Ever increasing demands are being placed on medical device manufacturers. These include packaging operations located at diverse global locations, which require the same specification of product to be achieved by the different lines in each of those different regions; the increased need for speed to market; high manufacturing output rates; more scrutiny regarding validation; packaging consistency; and more aggressive sterilisation methods. The new developments in flexible packaging now offer the package designer a much wider selection of options to meet those challenges.
The arrival of new materials provides choice and requires packaging manufacturers to be much more thorough in their approach to materials and validation. Device validation according to ISO 11607 for terminally sterilised packaging, including sterile barrier system (SBS) packaging, can take from 6 to 36 months, depending on available resources, which is clearly a disincentive to changing packaging format and/or materials.
One way to address this issue and to benefit from a new material technology is to obtain data from the packaging supplier. For example, in the case of a film sealed to uncoated paper or Tyvek, the packaging manufacturer may use the ISO 11607 protocols not only for the film itself, but also for the SBS combinations of film with uncoated Tyvek or paper lidding. This allows data to become available for five year accelerated and real-time ageing after sterilisation. Device manufacturers can then use these data as part of their validation protocol and thereby save considerable amounts of time and money. As film technology advances further and the additional costs of material coating become unnecessary with the advent of more peelable films, as described above, the provision of additional data such as these will allow greater packaging choice and faster
packaging changes to become a reality.
is Executive Director, Global
Medical Flexibles, Sealed Air Medical Applications, 200 Riverfront Boulevard, Elmwood Park 07407, New Jersey, USA.
is Marketing Manager, Sealed Air Medical Applications, Fleets Lane, Poole BH15 3BT, UK tel. +44 1202 781 241
* To whom all correspondence should be directed.