EO Sterilization validation
Medical device sterilization validation is one of the most important elements of medical device Validation & Verification plan, since compromised state of sterility of medical device could impact the patient’s health or, in severe cases, lead to patient death.
Sterilization describes the process that destroys or eliminates all forms of microbial life, rendering products sterile – free of viable microorganisms. Sterilization can be achieved through various means, both physical and chemical. Physical methods include steam under pressure (autoclave), dry heat and gamma irradiation, while common chemical methods include sterilization by Ethylene Oxide gas.
Key advantages of sterilization by Ethylene Oxide
- EO sterilization is the method of choice for medical devices that cannot withstand high temperatures and moisture;
- EO sterilization is particularly suitable for devices with long lumens (such as catheters and endoscopes);
- EO Sterilization is compatible with most materials used in medical device manufacture.
- EO sterilization is one of the most used sterilization methods worldwide with a long history of use, accepted globally by regulatory authorities
EO sterilization effectiveness depends on the ability of Ethylene Oxide to penetrate through all packaging materials to the most difficult-to-sterilize location in your product. The EO sterilization process depends on control of four parameters: EO concentration, temperature, relative humidity, and EO exposure time.
The ISO 11135 standard outlines requirements for Ethylene oxide sterilization process development, validation and routine control of a sterilization process for medical devices.
What is Gamma Irradiation?
The gamma irradiation process uses Cobalt 60 radiation to kill microorganisms on a variety of different products in a specially designed cell. Gamma radiation is generated by the decay of the radioisotope Cobalt 60, with the resultant high energy photons being an effective sterilant. A key characteristic of gamma irradiation is the high penetration capability, which allows for delivery of target radiation dose to areas of products that may be higher in density.
The unit of absorbed dose is kiloGray, expressed as kGy. Delivery and absorption of dose by product is determined by product density, packaging size, dose rate, exposure time and facility design.
What is Gamma Irradiation Used For?
The gamma irradiation process can effectively treat a wide variety of products composed of different materials, with varying densities, configurations and orientations. Some examples of products processed include:
- Medical devices
- Combination drug/device products
- Tissue-based and biological products
- Animal retail products
- Cosmetics and toiletries
- Horticultural supplies
- Packaging materials
What are the Benefits of Gamma Irradiation?
Gamma irradiation is safe, reliable and highly effective at treating a wide variety of products with varying densities. With the ability to penetrate products while sealed in their final packaging, gamma irradiation supports the manufacturing and distribution process by facilitating final packaged products as well as raw material needs, ensuring full sterility of the product.
Gamma sterilization is supported by the internationally recognized consensus standard, ISO 11137, which describes the approach to validating a dose to achieve a defined sterility assurance level (SAL).
Electron Beam Irradiation
What is Electron Beam Irradiation?
In the electron beam process, a product is bombarded with high-energy electrons, resulting in a cascade of these electrons moving through the target material.
The E-beam process utilizes high energy electrons as its radiation source. The electrons, which are produced by normal electrical current, are accelerated to near the speed of light by means of an accelerator. The electrons are focused to a scan horn of a defined size and scanned in a sweeping motion, creating a curtain of electrons. The product is then conveyed through the scan curtain at a tightly controlled and measured speed.
The process itself takes place behind a radiation shield, typically a large concrete structure, which prevents radiation from leaving the cell. As scanning occurs, the accelerated electrons inactivate any viable microorganisms.
What is Electron Beam Irradiation Used For?
Electron beam irradiation is a flexible and high-speed process that can be used for a variety of applications, including:
- Sterilization of single-use medical devices and pharmaceutical
- Contamination control in packaging, cosmetics, and toiletries
- Strengthening of polymers due to cross-linking and/or breaking down of polymers
What are the Benefits of Electron Beam?
E-beam irradiation can penetrate a wide range of materials and deliver the required irradiating dose in just a few seconds, meaning the entire process can take place in minutes. As a result of this short exposure period, the following benefits have been found:
- Optimized processing times
- Improved supply chain efficiencies
- Considerably less oxidative damage to the product
- Reduced color change in any present polymers
- No chemical residuals or induced radioactivity remain on processed products
Electron beam sterilization is supported by the internationally recognized consensus standard, ISO 11137, which describes the approach to validating a process to achieve a defined sterility assurance level (SAL).
Vaporized Hydrogen Peroxide
What is Vaporized Hydrogen Peroxide?
Vaporized hydrogen peroxide (VHP) is a deep vacuum, low-temperature vapor process that has traditionally been used for sterilization of reusable medical devices in patient care facilities.
VHP is compatible with a wide range of polymeric materials, making it an effective sterilization method for single-use healthcare products such as:
- Implants and devices with electronics
- Pharmaceutical containers
- Parenteral drug delivery systems such as pre-filled syringes
- Combination delivery devices
- Single-packaged assembled complex devices
- Complete assemblies or devices with loose components (e.g. needles)
- Temperature sensitive devices
The Vaporized Hydrogen Peroxide Sterilization Process
The VHP process includes three phases: Conditioning, sterilant exposure and post-conditioning, with all phases performed within a single chamber. The process is carried out under deep vacuum conditions of typically 1-10 millibar (0.03-0.3 inches Hg), with a temperature range of typically 28-40°C (82-104oF).
Total cycle time (from door closed to door open) is typically eight hours or less. However, cycle time may vary depending on product composition, packaging materials, temperature, and load size and configuration.
Steam Sterilization is a simple yet very effective decontamination method. Sterilization is achieved by exposing products to saturated steam at high temperatures (121°C to 134°C).
Product(s) are placed in a device called the autoclave and heated through pressurized steam to kill all microorganisms including spores. The device’s exposure time to steam would be anywhere between 3 to 15 minutes, depending on the generated heat.
Steam sterilization process is not appropriate for many materials due to the high temperatures involved.
Some quarantine/down time is required once products have been sterilized. Sterilized packages need to be allowed to dry before being removed from the autoclave to prevent contamination. Once removed, they must be allowed to cool to ambient temperatures, which may take several hours.
For effective sterilization it is critical that the steam covers all surfaces of the device.
To ensure optimal conditions, many autoclaves have built in meters that display temperature and pressure conditions with respect to time. Biological indicator devices and Indicator tape which changes color are also used to gauge the performance of the autoclave. The chemical tape is placed both inside and outside the sterilized packages, whereas bioindicator devices release spores inside the autoclave. The spores are incubated for 24 hours at the end of which time their growth rate is measured. If the spores have been destroyed it indicates that the sterilization process was effective.
ISO 17665 specifies requirements for the development, validation and routine control of a moist heat sterilization process for medical devices. Moist heat sterilization processes covered by ISO 17665-1:2006 include but are not limited to:
- Saturated steam venting systems
- Saturated steam active air removal systems
- Air steam mixtures
- Water spray
- Water immersion
ISO 17665 covers sterilization of solid as well as liquid medical devices. According to the standard it is the manufacturer’s responsibility to develop the process and provide guidelines/ instructions for operation and validation of the process. The standard also requires detailed documentation of all conditions that affect the process performance now and in the future. ISO 17665-1 only provides very general guidelines on steam sterilization requirements and operations. ISO 17665-2 tries to describe these guidelines more specifically through the use of examples and further explanation.
How can we help?
Since 2010 GemarMed has been working with both domestic and international customers to formulate and execute successful regulatory activities and quality assurance, exclusively serving the medical device industry.
We can provide expert service to support your sterilization projects:
- Product/packaging design considerations with respect to sterilization
- Product families and procedure kits – establishment of representative device
- Load configuration to meet current and future goals of your company
- Sterilization validation study design
- Process Challenge Device design and feasibility testing
- Single Batch Release
- Annual Requalification, risk assessment in case of Requalification failure
- Assessment of impact of a change on validated sterilization process
- Product adoption into validated sterilization process
- Laboratory testing strategy (microbiology/EO residuals).
- Audit of sterilization subcontractor’ facilities, IQ/OQ reports review
- Project Management
We will be happy to supply additional vital information in the field of sterilization and assist your efforts towards achieving a better product.