FDA Proposes New Sterilization Requirements For Medical Devices

The industry is moving away from ethylene oxide (EtO) sterilization, citing environmental impacts.

On January 8, 2024, the FDA (Food and Drug Administration) issued a press release stating that it revised its final guidance on submissions for devices labeled as sterile to permit the use of VHP (Vaporized Hydrogen Peroxide also known as VPHP) a Category A sterilization method. This should pave the path for companies to employ VHP where, in the past, ethylene oxide (EtO) sterilization was the method of choice.

Transitioning to a new sterilization method is a process that takes significant lead time. Let us guide you through the long process to help you meet critical deadlines that will be required by FDA.

Where Did This Decision Stem From?

This decision comes on the heels of public concerns about environmental hazards resulting from ethylene oxide, including a $408MM settlement in 2023 with medical device sterilizers in Illinois, with other cases pending.

Prior to this industry move, VHP was known as a sanitizer, but was not accepted by the FDA as a sterilization method, where sterilization carries the requirement of a 10^-6 reduction in microbial growth, with sanitization having reduced requirements for microbial removal.

EPA Lowered EtO Emission Limits

As a partial mitigation to the health problems linked to EtO use, including cancer risks, the EPA (Environmental Protection Agency) lowered its EtO emissions limits in April of 2023, effective October 2024 to provide time for industry to adjust.

Databases Updated To Support Alternate Sterilization Methods

Inter-agency co-operative efforts then updated its Recognized Standards database to include standards and information supporting sterilization though low-temperature vaporized hydrogen peroxide as an alternative. Previously, the FDA did not recognize a standard method for VHP sterilization, resulting in industry shying from its use.

Now that the FDA recognizes this sterilization method, it is incumbent on industry to ensure that this method is properly employed, and more importantly, properly validated.

When VHP Should + Shouldn’t Be Used

VHP is inappropriate at times, and it is not foreseeable that EtO sterilization will be abandoned altogether in the near future. The table below outlines the advantages and limitations of each sterilization method, including VHP.

Proper use of VHP therefore requires verification that the method is compatible with the product. Similar to autoclaving, VHP cycles and loading patterns must be developed specific to the product, as multiple vacuum/injection cycles are necessary to assure full penetration of the hydrogen peroxide inside the material enclosing the product.

Understanding Hydrogen Peroxide Cycles

Unlike EtO or autoclaving, hydrogen peroxide requires several cycles to fully penetrate. Despite the multiple cycles, dwell times are reduced, resulting in a VHP cycle that is shorter than a similar EtO cycle.

Tyvek® Usage

Tyvek® or similar material is recommended for covering the device because of VHP’s incompatibility with cellulose and its difficulty in penetration. Furthermore, VHP must only be used for a device in its primary covering and cannot be used if the device is enclosed in outer packaging materials.

Consider The Risk Of Hydrogen Peroxide

Another limitation to consider is that residual hydrogen peroxide may be a risk for medical device compatibility and patient needs.  The firm’s risk management program must consider these risks and validation testing may require establishment of residue limits and enhanced testing during validation and routine testing at product release

VHP is unique from other sterilization methods, in that hydrogen peroxide exists in equilibrium with water, and, as a free-radical, naturally degrades into water and oxygen on its own.

During cycle development, vacuum cycles must be tightly controlled to prevent humidity buildup and water condensation within the chamber, which has the potential to damage some medical devices. It is recommended that if a medical device is highly-sensitive to the presence of liquid water, avoid VHP.

Occluded Surfaces + Passive Diffusion Areas

Items to consider are occluded surfaces and passive diffusion areas. An occluded surface is an area or location which is completely obstructed from VHP exposure. An occluded surface will not be decontaminated as VHP has poor penetrating abilities.

Passive diffusion is the net movement of VHP-laden air from an area of high concentration to an area with lower concentration. Examples areas that may rely on passive diffusion of VHP would be Pipe Dead-Legs or within a container.

Validation

Once cycles are properly developed, validation is required to ensure that the process is repeatable. Similar to autoclave validation, it is recommended to perform at least some testing under a shortened cycle, and to specify the load pattern(s) for the product inside the chamber.

Biological indicators are like those used for autoclaving (Geobacillus stearothermophilus), but are developed for hydrogen peroxide penetration. Chemical indicators are strips coated with indicator ink that demonstrate a gradual color change upon exposure to hydrogen peroxide gas.

These indicators are used to visually assess the gas distribution through various locations in the target material. Sensors have been developed to measure conditions within the VHP chamber, to compare equipment settings to measurements within theoretical worst-case locations within the chamber to assure optimal sterilization performance.

How Will You Validate Your VPH Process?

We hope that this guide to VHP validation is helpful to you. The sources below provide more technical background if you would like to learn more.

To aid with this necessary transition, Compliance Team can assist with critical method verification and VPH process validation that will be mandated by FDA. Get in touch with us here.