Validating the sterilization process for a new medical device can take more than eight weeks and cost thousands. Companies will have to supply several packaged samples, which is not a big deal if you're talking about a device that will be made in the thousands. But what if the device is expensive and only a hundred will be made? Then running additional product samples becomes extremely costly.

Regulatory bodies understand this predicament and have documented a rationale for product adoption — using a validated ethylene oxide (EO) sterilization process for similar devices.

But sterilization employees leave, companies change, and the idea gets lost or confused as companies grow. So it's good to occasionally revisit exactly what product adoption entails

TIR-28

Although the concept of product adoption sounds simple, applying it to the auditor's satisfaction is not that easy. To assist in doing so, the Association for the Advancement of Medical Instrumentation (AAMI) issued the technical information report or TIR-28 a few years ago to guide companies and sterilization specialists through the idea's proper application with a range of guidelines and suggestions. The main body is only five pages and may be one of the more readable technical guidelines.

The TIR says product adoption is the process of formally including a candidate product into an existing validated sterilization process. The trick to successfully applying product adoption is to recognize and justify families of products, those that are similar in construction, materials, size, and packaging. Then the most difficult to sterilize device in each group will be the process challenge device or PCD. If a sterilization process works for the PCD, it should work for other devices in the family.

Grouping products into families takes some thinking. The TIR provides a checklist in section 4.2 Families. The nonexclusive checklist is important because companies must document how and why they classify something, or provide historical background for why a device is in a certain group.A sterilization specialist should comment on each point in the list to document that each was considered.

There is, however, no clear or accepted description for a sterilization specialist. Generally, that person should be informed, appropriately trained, have experience, and be trusted with the company's sterilization matters. Product familiarity is also key to the success of this process.

Medical-grade tubing made of silicone provides a simple example. Suppose this identical tubing comes in 2, 4, and 8-ft lengths. The longest piece, of course, will be the worst case or most difficult to sterilize due to the gas path. But take this same tubing applied with varying lumen sizes, endcaps, or other fittings and it may change which device becomes the PCD.

Document, document, document

The device manufacturer, first of all, is responsible for the validation and explaining it to auditors. Auditors want to be sure the challenge device represents the worst case in a particular product family. So justify in writing why you think so. State, for example, that the existing validation sequence applies to a new 6-ft tubing with a larger lumen because it's packaged in the same configuration, manufactured in the same environment, and made of the same materials. The FDA wants to see that a company is aware of differences and similarities in products and it is not making rash assumptions without documentation or testing to back up their theory.

Document also how you are configuring the product family. Auditors expect to see a written rationale that shows you have sound logic for grouping products into these families. Industry regulators understand the time and cost on companies. What they don't want to read is that people have, for example, placed all products with tubing into a tubing family. If the tubing materials differ, the rationale for the family can fall apart.

It is also a good idea to look ahead to new or future products. This can save a company a substantial amount of money. For example, suppose a company has validated the same identical tubing in 2, 4, and 6-ft lengths. If it knows a 12-ft version is likely, make it and validate it because it will be the worst case. After validating the 12-ft. version, the existing three shorter versions can be validated under a documented paper adoption.

Remember, you know your product better than an auditor in most situations. Document your rationale for sterilization validation, and be prepared to provide supporting documentation if needed, regarding materials, packaging specifications, and so on.

Most auditors are busy these days so it's not likely you'll get a response if you send them your family rationales and ask for comment. But when ISO auditors are in, ask them for an off-line review. Their primary goal is to help you improve your quality system.

Annex A of TIR-28 includes four questions to assist with comparisons that find family members. The four are not inclusive. But the Annex says if the answer to any one is “yes,” a new product or variation thought to belong in a particular family needs further evaluation. Remember, the candidate product should not be more difficult to sterilize than the existing validated product.

• Products in a family should have a similar configuration. Does the candidate product have a more restrictive passageway than the existing one, fewer openings, internal surfaces, or closures?

• Similar materials and characteristics. Are the materials known to retain higher EO residuals? Are they from the same source? Can they withstand the same temperature and pressures?

• Similar primary package configuration.

• Products in the family should have similar package density and similar thermal dynamic response to the process.

Make contact

Centurion Sterilization Services, (866) 386-0530, centurionsterile.com

It's all about families

Section 4.2 in the AAMI TIR-28 provides guidance for justifying the placement of products into families with a list of 10 classification considerations. It may be necessary to show the auditor your written rationale for grouping families as you did, so it's a good idea to say something about:

• Product design of the family and the PCD

• Product function or end use

• Manufacturing method or type of equipment utilized

• Manufacturing environment. Where was the product made?

• Construction materials. Two visually similar devices made of different materials, PVC and silicone, for example, might belong in different families. Residual gas may vary substantially.

• Packaging materials. Is the device in a breather bag, pouch, or packaged in rigid materials?

• Primary, or secondary packaging configurations, or both. Are there multiple layers?

• Density

• Size, or surface area, or both

• Bioburden. Less initial contamination on the product makes it easier to sterilize.

The protocol - who does what

The protocol provides step by step instructions as to what the contract sterilizer will do to validate a new or modified product. It describes what will be done and by whom and includes particular products, processes, and test requirements. Our company puts as much relevant information into the protocol, as possible so there is no doubt where responsibility lies. Companies can generate their own protocols or utilize their contract sterilizer or a consultant to develop one.

A brief glossary

These few terms from TIR-28 might be useful to those in liaison with sterilization companies.

Candidate product: New or modified product including the packaging system, proposed for inclusion into an existing validated sterilization process.

Packaging system: Entire packaging for a product consists of the sterile barrier (primary package), the carton or shelf package (secondary packaging), and the shipping container (tertiary packaging).

Product challenge device, the PCD: An object that simulates the worst-case of conditions as they are given for a sterilizing agent and in terms of the goods to be sterilized.

Product family: A collection of products that are determined to be similar or equivalent for validation purposes.

Sterility assurance level, SAL: Probability of a viable microorganism being present on a product unit after sterilization.