By Sean Fenske, Editor-in-Chief

Sterilization has become a significant topic of conversation among medical device manufacturers. Between the EPA looking at ethylene oxide (EO) facilities and, more specifically, the emissions from them and new and emerging sterilization alternatives, companies are taking a long look at their options. The traditional EO and gamma may not always be the best choice.

While it’s great to have options for a medical device, approaching this selection process the right way is critical. Additionally, it may be prudent to validate multiple sterilization methods for a new product rather than just settling on one method. Unfortunately, this can create confusion and uncertainty. Knowing what factors must be considered for each process is not something with which many are intimately familiar.

For this reason, it’s important to have a partner who can help identify the best sterilization process for a new development. Fortunately, Sopheak Srun, Principal Sterilization Scientist, and Molly Swanson, Senior Sterilization Scientist—both from Cretex Medical | QTS—addressed this topic. In the following Q&A, they speak to consideration factors, recommendations they are making, and newer alternatives.

Sean Fenske: What’s driving the discussion over medical device sterilization? Why are companies considering alternative methods?

Sopheak Srun: Ongoing capacity constraints are the biggest issue in medical device sterilization. This is primarily driven by two factors: increased scrutiny of EO sterilization (which comprises approximately 50% of the sterilization market), and supply issues with the cobalt-60 (Co-60) used for gamma sterilization (which comprises ~40% of the sterilization market).

EO is highly effective for destroying microorganisms, but those properties also make excessive, inadequately controlled emissions from EO facilities carcinogenic. This has led to public protests, and the resulting pressure has caused a number of EO facilities to be shut down. This has put a strain on capacity.

Meanwhile, the processing capacity of gamma sterilization facilities has been limited. Those companies rely on Co-60, which can only be produced by a limited number of providers. Those organizations, in turn, do not have the capacity to accommodate the projected growth in the medical device industry.

The pressures on these two modalities, which perform ~90% of all medical device sterilization, are driving more and more companies to explore sterilization alternatives.

Fenske: When determining the best sterilization method for a device, what are the most important factors a company must consider? What are the most relevant variables?

Molly Swanson: At Cretex Medical | QTS, our team of on-site certified microbiologists and sterilization specialists work closely with customers to evaluate their sterilization needs to help them find solutions that manage costs while ensuring patient safety. There are several factors we consider. That includes material composition and its compatibility with each sterilization modality. The size and geometry of devices, if particularly large or complex, can limit the modalities used for sterilization. Additionally, there are other variables including time constraints, packaging considerations, available sterilization capacity given the anticipated production volumes, and logistical considerations. Which variables most impact decision making can vary by the unique needs of each device and customer. That’s why having a trusted partner with industry-leading expertise is vital for medical device manufacturers considering their sterilization options.

Fenske: Given capacity, technology, cost, etc., how are you advising customers on their choice of sterilization?

Srun: One option we’ve found to be very helpful for our customers is QSTERILE®—our proprietary pre-validated EO cycle. While the traditional half-cycle overkill approach has historically often been used with a high concentration EO cycle and has been popular due to its high validation success rate, the high volume of EO used can be problematic with regard to emissions. QSTERILE, on the other hand, reduces EO emissions by using the cycle calculation approach combined with a low concentration EO cycle. That also helps to minimize cycle times, meaning less stress on EO facility capacity, all while ensuring a safe and sterilized product.

With QSTERILE, a performance qualification runs using representative dunnage in accordance with ISO 11135, meaning you only need to conduct product-specific testing to integrate your items into the cycle. This proprietary service can save you both time and money by eliminating the need for a full EO sterilization validation on your end.

Fenske: Do you recommend validating devices so they can leverage different sterilization modalities as a fail-safe? What are the advantages/disadvantages to this strategy?

Swanson: To mitigate the risk of supply chain bottlenecks, we encourage customers to qualify multiple sterilization modalities when possible. Qualifying additional modalities will take time and add complexities (from compatibility concerns to costs to regulatory considerations). However, performing this planning up front is preferable to being caught unprepared if the primary modality is disrupted by an unexpected capacity shortage.

Fenske: Are there emerging sterilization methods you are exploring or find interesting for the medical device industry?

Srun: To ensure we can continue to give the best advice to our customers, we have evaluated a range of alternative modalities, including vaporized hydrogen peroxide, nitrogen dioxide, and other emerging technologies. While these methods are promising in certain applications, many of these approaches currently face limitations in supply chain capacity, making them less viable for high-volume production at this time. They also come with additional challenges such as extended process validation timelines and regulatory approvals. Still, we will continue to closely monitor developments in these technologies, as in the long run they may become more practical as sterilization solutions for our customers.

With that said, a number of companies are building x-ray sterilization facilities in the U.S., which will offer a viable alternative to gamma sterilization. So far, most of these facilities have focused their efforts on transferring food products from gamma to x-ray, which helps to free up gamma sterilization capacity and buy medical device manufacturers more time to eventually adopt the use of x-ray for their products. Additionally, advancements with virtual dose mapping will make it easier for more device companies to adopt the use of e-beam sterilization, which historically has been a bit more cumbersome due to its reduced penetration compared to gamma or x-ray.

Fenske: Should companies develop devices for a specific sterilization method or match the device to the best option given the device design after design freeze? What approach is best?

Srun: The primary consideration in device design is always going to be the health and safety of the patient. But there may be many ways to ensure that. In design and development, thinking through sterilization needs should definitely be a consideration, as should material costs, geometry, and overall design-for-manufacturability. At Cretex Medical, we have experts from across our family of companies who can work closely with customers to find the solutions that create the most efficiencies while best supporting patient outcomes.

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