Regional One Health

Ruth Plotkin Shumaker

As product development continues in the medical device space, packaging and sterility assurance are being viewed through an innovative lens. The innovation lens provides fresh insight, casts a new light over the market, which inspires innovation excellence. Environmental concerns, cost savings, and speed have led medical device manufacturers to research and better understand various sterilization modalities. There are various types of sterilization equipment and multiple packaging materials to consider. Care must be taken to ensure the materials are compatible with the sterilization process. In selecting the materials for sterile barrier systems, it is important to understand the sterilization process that they will be subjected to and its limitations. It is essential that any detrimental effects of the process on the materials do not affect the overall functionality of the sterile barrier, subsequent storage and usage of the device.

Packaging materials-include wrapped perforated instrument trays, peel pouches of paper, plastic or paper/plastic, and sterilization wraps which can be either woven or unwoven. Packaging materials should be designed for the type of sterilization process being used and should be appropriate for the items being sterilized. Ensure that packaging materials are compatible with the sterilization process and have received FDA 510[k] clearance. Packaging materials (e.g., wrapped or peel pouches) allow penetration of the sterilizing agent and maintain sterility of the processed item after sterilization. Packaging must allow the packages to be opened easily and aseptically. Packaging must be permeable, water repellent, resistant to tears and impermeable to microorganisms. After sterilization, the packaging must keep the instruments sterile until used.

Sterilization Technologies-Medical devices are sterilized in a variety of ways including using moist heat (steam), dry heat, ethylene oxide gas, vaporized hydrogen peroxide, radiation and other sterilization methods (for example, chlorine dioxide gas, vaporized peracetic acid, and nitrogen dioxide).

Steam sterilization allows sterilization of a wide range of materials. Steam is the preferred method for sterilizing critical medical and surgical instruments that are not damaged by heat, steam, pressure, or moisture. Steam sterilizers (autoclaves) are the most popular method of sterilization. If using steam sterilization the packaging material requirements should allow steam to penetrate the package. One factor to consider is whether a gravity or prevacuum process is being used. If it is gravity, you do not want air entrapment between the package and the product. If that happens, it may not deliver the efficacy of sterilization you expect. If it is prevacuum, make sure you are using a packaging material that can withstand a very rapid evacuation process.Acceptable materials for steam sterilization are paper plastic, paper/plastic peel packages; sterilization wraps which can be either woven or unwoven.Foils are not compatible.

"Environmental concerns, cost savings, and speed have led medical device manufacturers to research and better understand various sterilization modalities"

Ethylene oxide gas (ETO) can sterilize heat or moisture-sensitive medical equipment without deleterious effects on the material used in the medical devices. However, ETO gas is highly flammable, explosive and a toxic/carcinogenic. Cycle times are relatively long, particularly post-sterilization because aeration is required to remove toxic residuesremaining after the sterilization process. Ethylene oxide penetrates well through porous materials such as medical grade paper and polyolefin nonwoven materials which have adequate porosity. The packaging used for ETO sterilized medical devices must combine sterile barrier properties and breathability to allow gas penetration and removal. It must also be resistant to vacuum.

Hydrogen Peroxide Gas Plasma sterilization is beneficial for materials and devices that cannot tolerate high temperatures and humidity, such as some plastics, electrical devices, and corrosion-susceptible metal alloys. One disadvantages of gas plasma sterilization is paper, cellulose or linen products cannot be sterilized using hydrogen peroxide because it reacts with the fibers. This weakens them and there is little if any peroxide left to act as a sterilant. Permeable polymer based materials such as non-woven materials of polyolefin must therefore be used.

Dry heat sterilization Dry heat is not a common sterilization modality in hospitals. It is frequently used in sterilizing dental instruments, Dry-heat sterilization can be used to sterilize items e.g., powders, petroleum products, oils that can sustain high temperatures. Acceptable sterilization materials are paper bags, aluminum, foil, polyfilm plastic tubing and wrapped perforated trays.

Radiation sterilization is a method used by industry for sterilizing single-use medical devices.Gamma sterilization may be performed on individual boxes, in irradiation containers usually referred to as totes, or on pallets.

Shelf Life-The shelf life of a packaged sterile item depends on the quality of the wrapper, conditions during transport, storage conditions, amount of handling, and events that compromise the integrity of the package. Storage practices for wrapped sterilized instruments are event-relate and can be used indefinitely unless the packaging is compromised, torn or wet.

Conclusion The right choice for a medical package depends on an understanding of the effects materials and the sterilization processes have on one another. It is possible to select and validate an appropriate packaging material and compatible sterilization technique. To do so, it is important to select the proper material and sterilization conditions that will provide a sterile and safe product. Whether you select packaging materials based on compatibility with a sterilization method in place or select a sterilization method based on compatibility with packaging materials in place, it is important to understand the effects they have on each other. It is also important to keep pace with changes in sterilization technology, as those could prompt a rethinking of packaging materials.