Determining What’s “Production Equivalent” with a New Product Design

Q: I’m dealing with a design contract house responsible for product design of a medical device. They are responsible for all of the documentation needed for design control, etc.

If we produce the first 100 units via the contract house, those units will be saleable and used by the customer. The supplier will do process validation at its location for its respective build. In addition, the final assembly location (not the supplier) for production will perform process validation.

Do you see any issues or concerns with this approach to product design?

A: Perhaps. The design validation units will have to be either production or production equivalent units.

Here’s the criteria you should use:

  1. If the first 100 units are made at the design house with a “frozen” design and a validated process (either a “frozen” production process or one that is nearly complete), and…
  2. If the components, raw materials, etc. went through an approved in-coming acceptance activity with approved acceptance criteria, and…
  3. The units are made with similar equipment and personnel who will build the next 100 or more units…

…then you can demonstrate the units as production equivalent.

But if the method of manufacture is significantly different than normal production, then the units would NOT be production equivalent. The production differences could include things like different equipment; different levels of personnel experience; different in-coming, in-process or finished device acceptance procedures; and different methods and criteria.

For example, if the first 100 units are built by the product design engineers, the units won’t be equivalent. If the first 100 are built using manual processes (such as manual welding), but future devices will be built using automated processes, the units won’t be equivalent.

You will need to repeat some — if not most — of the design validation performance and functionality activities once you transfer the design from the design contract house to the regular production facility.

You can take the approach you’ve described, but you will need to repeat some — if not most — of the design validation performance and functionality activities once you transfer the design from the design contract house to the regular production facility.

Process validation only proves that the process can build a device to your design intent and that the process can be kept in a state of control with appropriate monitoring.

So the mere fact that both production processes are validated does not answer the design for manufacturing (or servicing) question which is answered only with true design validation:

Is my device safe and effective, and will it perform and function as described in my initial design input requirements and as my customers need and expect according to my specified design outputs — including my specified method of manufacture? 

When you change the method of manufacturing, you also need to assess the ability of that method to produce a device that is safe and effective. You need to understand whether or not (and how) the manufacturing method could impact your finished design. Does it produce the same design as the other method?

Passing a finished product inspection will not necessarily always answer that question; it will depend on the actual device and its design.

Answered by Denise Dion, Vice President of Regulatory and Quality Services for EduQuest, who served 18 years at the U.S. FDA as an expert field investigator and was a member of FDA’s Design Control Inspection Strategy Team. Denise is the lead instructor for EduQuest’s 2-day training class, Design Control for Medical Devices.

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