I am in need of assistance in picking the right packaging for a disposable bioburden filter apparatus that will be gamma sterilized. The packaging needs to be user friendly, provide a reliable sterile barrier, and be radiation tolerant. How do I go about selecting the appropriate material for this application?
Product protection, sterilization, distribution and handling, and expected shelf-life requirements of a product are just some of the details that define the package that will maintain sterile barrier protection of a product until use.
There are many materials in the medical device market today that are compatible with radiation sterilization. Some have a high resistance to the effects of gamma sterilization, while others are more suited to lower dose sterilization cycles.
Polymers can react to radiation sterilization in several ways depending on the exposure level. Some materials are essentially unchanged by radiation and maintain their mechanical properties, while other materials are altered. Many polymeric materials are susceptible to chain cross-linking or chain-scission after exposure to radiation. Both of these chain alterations will have some level of impact on mechanical properties.
In the case of chain scission, the polymer chain is cleaved or cut by the radiation. Polymers that are susceptible to radiation-induced chain scission often lose elongation properties after radiation sterilization. The level of chain scission will increase proportionally to the level of radiation exposure. In severe cases, the loss of elongation may result in the material becoming stiff, brittle and susceptible to shattering.
Cross-linking of a polymer chain occurs when bonds form between adjacent polymer chains. In some cases a low level of cross-linking can improve a polymeric material’s mechanical properties. However, in highly cross-linked materials, individual polymer chains lose their ability to slide against one another thereby reducing the material’s ability to elongate. Similar to chain scission, highly cross-linked polymeric materials can also become brittle and susceptible to shattering.
When beginning the process of material selection it is highly recommended that one refer to AAMI standard documents for guidance: TIR17- Compatibility of materials to sterilization and TIR22- Guidance for ANSI/AAMI/ISO 11607, Packaging for terminally sterilized medical devices—Part 1 and Part 2:2006. Since many packages are often composed of multi-layer composites, the best approach is to speak with your package or material supplier regarding compatibility of materials to sterilization.
Making a package user friendly also has a number of aspects to it that can affect the decision – need for visibility of the product, printability for identification and labeling, opening features for aseptic presentation – to name a few. Materials can be designed to allow seals to be peelable for presenting products aseptically into a sterile field, for example. In the case of bulky, heavy weight products, non-peelable weld seals may be required. Some products may have rigid or sharp edges, rough surfaces, or knobs that require packaging materials that can support these products through distribution testing where abrasion and puncture can occur. Lighter, low-profile items may increase material options in package design. All processing steps should be validated to confirm adequate capability for package production and seal integrity.
To add to this list of details that help define the protection of a product through maintenance of sterility until use, there is also the consideration of package disposal after use that may affect decision-making. Your sterile packaging manufacturer can help you maneuver through these decisions and provide an answer that can help you towards your company’s final testing for approval and acceptance.