Medium-voltage electron beams

Recent shutdowns of ethylene oxide (EtO) plants in the U.S. and limited worldwide availability of cobalt-60, are rapidly changing the medical device sterilization market.

The EtO closures have raised the need for FDA-cleared technologies as replacements. With limited options available to meet demand, an existing technology offers an alternative: medium-voltage electron beams. Intermediate level of penetration makes the beams relevant for sterilizing medium- and low-density products and high-density devices when repackaging is an option.

Medium-voltage electron beam technology fits terminal sterilization of packaging materials and sterile barriers; implantable medical devices; combination, commodity healthcare, and single-use products; pharmaceuticals; dressings; and biomaterials. The technology is also compatible with sterilizing human tissues, controlled substances, and drugs.

Intermediate energy

Most electron beams used for bioreduction or sterilization of medical devices are high-voltage electron beam accelerators, typically of 10 mega electron volts (MeV), due to their superior penetration.

Medium-voltage, intermediate energy, electron beam accelerators emit radiation via high-speed electrons with 0.5MeV to 5.0MeV energy levels. While the energy dictates the penetration in medical devices, medium-voltage technology features high throughput, with 150kW beam power, compared to 10MeV machines which typically operate at considerably lower beam power. Throughput capability is proportional to kW.

Processing medical devices using medium-voltage electron beams is U.S. Food and Drug Administration (FDA) cleared and applicable when applied to medium- and low-density products, as well as combination devices, in current package configurations. At higher densities, sterilization is possible but often requires repackaging. The comparatively isothermal character of electron-beam processing is also crucial for several products, especially heat-sensitive ones.

Higher throughput makes medium-voltage electron beam technology cost- effective compared to high-voltage, low-kW beams. The lower energy levels involved cannot induce radioactivity in any material, so no radioactive waste is generated.

Sustainability, effective alternative

While there are advantages, medium-voltage electron beam technology is not suitable for the sterilization of every medical device due to penetration limits.

For packaged medical devices with relatively homogeneous internal densities, package height limitations for a medium- voltage electron beam are approximately:Incompatibilities may arise from product density and disposition in the secondary package, or depending on the container in which they are stored. Product composition may also impact the feasibility of the process as some materials are radiation-sensitive, but users can adjust some parameters or the processing conditions to make the process gentler and more suitable for the material’s needs.

Converting to a different sterilization technology is not simple, fast, or inexpensive, but the reduction in conventional options is driving change. EtO facility closures have already created shortages of some medical devices, but considerable sterilization capacity is available.

As an alternative to EtO or gamma processing, medium-voltage electron beam processing offers available contract sterilization capacity, equipment availability for in-house sterilization, economic advantages, and scalability.

E-Beam Services Inc.
https://www.ebeamservices.com

About the author: Gustavo Varca, B. Pharm, PhD., is a manager of new applications development at E-Beam Services Inc. He can be reached at gustavo.varca@ebeamservices.com.