The question of when to perform a single-batch release versus full sterilization is one we get often from medical device developers. There’s no one simple answer, but there always is an answer once you take time to consider the variables and do the math.

The top-line benefits of full validation are straightforward. Once the validation is complete, you can run with defined process parameters over and over again. In other words, full validations apply to future lots. You send product to your sterilization contractor when ready, and they can efficiently sterilize it using those parameters.

In contrast, as the name implies, single-batch release results apply only to the batch tested—not to future batches. A defined amount of material is sterilized in a single load.

Understand Multiple Variables

The complexity of deciding whether to run a single batch or a full validation stems from the presence of multiple variables. ISO 11135 standards provide detailed requirements for each.

Product and Chamber Size

Product unit size and the sterilization chamber size should be considered. Most contract sterilization contractors will offer different sizes of chambers. Each chamber size has its own advantages and disadvantages, but for a given chamber, the maximum quantity of product that can be sterilized in a single load is limited by the chamber volume.

Units Consumed by Testing

Next are standards specifying the number of product units required for testing. To illustrate, let’s say the contract sterilization facility can fit a maximum of 50 units of a given product in its chamber. Of the 50 units, per ISO standards, a specified quantity will need to be allocated for testing. In this scenario, the following are the minimum requirements for single-batch and full validation sterilization.

• Single-batch release: In each of the two required sterilization cycles, eight of the 50 units would be allocated for testing. After testing both cycles, that’s destructively testing 16 units, leaving the developer with 42 sterile units that are ready for release.
• Full sterilization validation: The sterilization validation would need to use 27 units. That’s almost twice as many as needed for a single-batch release. In addition, those units will not be immediately ready for release; the sterilizer would take one further step to use the validated process in a production run. However, the contractor can then sterilize routinely without performing device testing before release.

Costs and Time

Total costs and the time to complete the project should be considered.  A full validation typically costs about twice as much as a single batch release. In terms of time to completion, a single batch release typically takes five to seven weeks from the date the sterilization contractor receives the product. A full validation typically takes eight to ten weeks.

Product Design Changes

Developers of medical devices need to think carefully and realistically about potential changes they may make to their product. The type of changes can heavily influence the choice of single-batch release or full validation.

When you do a full sterilization validation on a product, there are certain changes you can make to the product and still be able to use the same validated sterilization cycle. In general, it would be decreasing the mass of the product you’re sterilizing, or increasing the diameter of the product’s smallest holes or torque-less paths.

However, if you think your product could experience significant design changes—such as to its material composition, length, or smallest diameter, or an increase in mass—then you may easily find yourself in a situation where you may need to do additional testing beyond the initial validation.

That said, there is a mechanism in some situations where three single-batch releases on the same product (with no design changes) can be turned into a validation.

Begin with the End in Mind

To make the best decision, developers need to begin the sterilization with the end in mind. If you are confident of your product design for your near-future needs, a full validation is usually the right call.

On the other hand, if you think your product—or its packaging—will change substantially, a single-batch release may be a good option. It also could make sense if you can fit a very large amount of product into the sterilization chamber, knowing the sterilized products would meet your needs for a long time.

Tips for Making the Call

The choice between single-batch release and full validation is not always clear.  These suggestions can help make the best choice.

Evaluate short-term gain versus long-term pain. A developer may be tempted by saving a few weeks and a few thousand dollars by opting for a single-batch release. But it often also means that they have little confidence in their design and aren’t sure of what will come next. Developers are generally better off getting further ahead with their product design before moving to the sterilization stage, recognizing that going with a single-batch approach early on may mean more testing and product consumption.

1. Plan ahead. Sterilization contractors—especially smaller, expert shops—are rarely the laggers in completing validations. Developers frequently request quotes, defer decisions, and then expect exceedingly fast turnaround—even without product ready. Developers who are invested in getting their products to market as quickly as possible would be wise to research sterilization contractors early on in the development process and select one that will be a good partner.
2. Work with a contractor experienced in product development, not only in sterilization. Given the variables, the decision between a single-batch release and full validation can be more complex than it initially appears. A vendor that is experienced in all aspects of product development—from ideation to market launch—will be in the best position to lay out the scenarios, do the calculations, and help make the best decision. They may also be able to provide invaluable input into the design and development process that will assure expediency when it comes to sterilization, packaging, and labeling.

Conclusion

Deciding between a single-batch release and a full validation requires analysis of product type, size, design, projected changes and developer confidence in their design. On the surface, a single-batch validation may be faster and less expensive, but a deeper look may lead to a better outcome with a full validation.

Jim Kasic is the founder, president, and CEO of Boulder iQ. With more than 30 years of experience in the Class I, II and III medical device industry, he holds more than 40 U.S. and international patents. His career includes experience with companies ranging from large multinational corporations to startups with national and international scope. Kasic previously served as president and CEO of Sophono Inc., a multinational manufacturer and distributor of implantable hearing devices that was acquired by Medtronic. He was also the president of OrthoWin, acquired by Zimmer-BioMed. He holds a Bachelor of Science in physics and a Master of Science in chemical/biological engineering from the University of Colorado and a Master of Business Administration from the University of Phoenix. Contact him at jim.kasic@boulderiq.com or on LinkedIn.