Steris LTS-V low temperature sterilizer chambers use vaporized hydrogen peroxide and come in four sizes ranging from 850 L to 9,000 L. [Photo courtesy of Steris]
The FDA’s addition of vaporized hydrogen peroxide (VHP) to its list of Established Category A methods offers an opportunity for manufacturers to bring device sterilization in-house.
VHP can be used as an alternative to ethylene oxide (referred to as EtO or EO) sterilization for many medical devices due to their similar material compatibility profiles. To skip the time and expense of shipping their products to a commercial EtO sterilizer, some device developers are considering adding a VHP sterilization chamber within their own manufacturing facilities.
To help device designers and engineers decide whether VHP is a good fit for their products, Medical Design & Outsourcing spoke with experts at Steris, which uses EtO, radiation and VHP to sterilize medical devices for its customers. Steris also sells VHP chambers and equipment that hospitals, drugmakers and device manufacturers can use in their own facilities.
Steris worked with ISO and the FDA for broader acceptance of VHP as a device sterilization method. The commercial sterilizer and equipment supplier was one of four companies participating in the FDA’s innovation program for EtO alternatives, and in January 2024 became the first (and so far, only) to get its alternative method — VHP — recategorized for medical devices.
“We’ve been working on the technology and trying to apply it and position it like-for-like with the older, traditional accepted technologies,” said Brian McEvoy, senior director of global technologies at Steris Applied Sterilization Technologies (AST).
Steris has been using VHP as a sterilization modality for more than two decades, with some of its first VHP sterilizers built for novel devices such as customized orthopedics. VHP sterilization at Steris then grew through its healthcare group for instrument reprocessing.
“Over those two areas, we have shown that it’s a really robust sterilization modality,” said Matt Hofacre, senior director of technical services at Steris.
Device manufacturers that can switch from EtO to VHP will free up capacity to sterilize other devices for which EtO is the only option.
“If we can add up more radiation opportunities, or we can add more VHP or novel technologies, we should continue to do so. We certainly wouldn’t see them as direct replacement technologies,” McEvoy said.
Best opportunities for taking device sterilization in-house
Despite their similarities, VHP can’t be used to sterilize all devices that are now sterilized with EtO. But there are many devices for which manufacturers should consider VHP.
Much of Steris’ early VHP development was with pharmaceutical companies for prefilled syringes and other drug delivery devices.
Now, VHP is showing increasing potential for single-use medical devices, of which about half are presently sterilized with EtO and half with radiation.
Another immediate opportunity to use VHP sterilization is with low-volume products like cardiac rhythm management devices and other implants with electronics.
“They tend to be done in-house because they’re made in smaller batches that need to move to patients much quicker. There’s a pretty straightforward substitution opportunity to take small EO sterilizers and replace with VHP sterilizers,” McEvoy said.
VHP can also sterilize hip, knee and skull implants. Personalized devices such as 3D-printed orthopedic implants may also be good candidates for VHP as additive manufacturing technology increasingly enables devices custom-made to fit a specific patient’s anatomy.
While some device manufacturers have encountered challenges using VHP to sterilize long-lumen devices, Hofacre said that doesn’t mean it can’t be done. Steris uses VHP for lumen device reprocessing and is finding VHP penetration in testing of devices with lumens, he said.
“Can we do an infinitely long, thin lumen? No. There are limitations to what you can do,” Hofacre said. “But to say VHP can’t do lumens is false. We have done them in various sizes and lengths, and it’s just a matter of looking at that design, doing the feasibility testing and seeing how it’s going to penetrate that device properly.”
Designing for VHP sterilization
Device developers considering the use of VHP — or any other form of sterilization — when designing their products and their packaging should consult with contract sterilizers or sterilization equipment suppliers early in the process.
“The earlier you can get into that conversation, the more you can influence what the sterilization process will look like at the end,” McEvoy said.
“From a contract perspective, it’s sometimes technology, but also logistics. We can find the right technology in the right location,” he said. “For the product designers [considering] radiation and material compatibility, if they come to us too late, there might one material in there that sensitive to radiation, and they might miss that opportunity for a very efficient radiation process. It’s no different with VHP.”
Steris recommends Tyvek packaging for VHP sterilization of medical devices.
“VHP is a gas modality, so you want to make sure you have a path for the for the vapor or the gas to get in,” Hofacre said. “Having the right channels and the right type of packaging is critical.”
How big of a hurdle is VHP’s cellulose problem?
VHP has excellent compatibility with most materials used to make medical devices, but one of the big challenges is its incompatibility with cellulosic packaging like cardboard and paper. That means you can’t sterilize entire pallets of boxed-up devices like you can with EtO — but then again, you don’t need to.
“Scale’s a consequence of shipping in trucks, “McEvoy said. “Supply chain is often more expensive than the sterilization process, so it’s a case of trying to maximize that supply chain, maximize that truck, get to a sterilizer, maximize the scale. … Scale is less of an issue when you remodel the supply chain.”
VHP sterilization changes the supply chain model by putting sterilization inside a manufacturer’s facility, allowing for in-line sterilization of products in primary packaging before they’re boxed up in in finished cartons with instructions for use (IFUs).
VHP sterilizers are much more compact than EtO sterilization, which requires a dedicated facility and carries risks of toxic emissions and explosions. Steris VHP chambers range in capacity from 0.5 pallets to four pallets. VHP sterilization cycles are also shorter than EtO because they don’t need post-sterilization aeration.
“You’re probably getting two VHP processes for nearly a standard EO cycle inside the sterilizer chamber. People are looking at the size of chamber, volume of chamber, but actually throughput and the volume over a period of time is also an important consideration,” McEvoy said.
Adding VHP device sterilization to your manufacturing line
Steris LTS-V sterilization chambers usually take two to four hours to sterilize medical devices, or up to 10 hours for sensitive products. [Image courtesy of Steris]
Because VHP sterilization is a faster, simpler and safer process than EtO, taking sterilization in-house with a VHP sterilization chamber will save some device manufacturers time and money.
These VHP chambers on the manufacturing line are fairly self contained, aside from utilities such as water, power and compressed air, Hofacre said. Wheeled trolleys load finished devices in their primary packaging in and out of the sterilization chamber.
“Everything you need to do the sterilization process is built into the machine. So it has the vacuum systems, the aeration systems, its own control system that can talk to the building management systems, etc.,” Hofacre said.
Steris also sells the consumable materials used for the systems and helps manufacturers with biological indicators and process challenge device (PCD) development for initial and ongoing validation.
The largest VHP chamber that Steris sells — around 9,000 L — can fit about four trolleys (each equal to about one pallet) worth of product at one time.
The future of VHP
Hofacre sees device sterilization as a new frontier with not only VHP, but also growing innovation in X-ray and e-beam sterilization.
“VHP is another tool in your toolbox for a sterilization modality. … Now having Category A status, it’s going to have a better path for acceptance by the regulatory bodies,” Hofacre said.
Look for advances in VHP sterilization as adoption grows due to the FDA’s move.
“With sustainable EO and advances in VHP sterilization technology, we feel we have a good one-two punch on tackling some of the constraints on the medical device sterilization capacity in the future,” Hofacre said. “We’re very hopeful about this. We are investing in this technology and you will see some good things to come down the road.”