It’s quite difficult to validate a rework procedure because, in most cases, you’re lacking numerous
batches to be able to show consistency of that rework procedure. This is basically a filing issue,
but at least from a GMP perspective, it’s quite difficult to validate a rework procedure because
you’re lacking multiple batches that failed for the same reason.
Reworking always required a prior approval and re-processing didn’t. We think we’ve got a lot of
people reinventing definitions and reinventing what was originally agreed upon, and things will
start to fall out as you shake the trees. But, you’re going to need to explore with the reviewing
branch when you start to get outside of the GMP part and get into the filing issue.
Section 14.3 says: “the batch should be subjected to appropriate evaluation, testing, stability
testing if warranted, and documentation to show that it’s equivalent”. This is a good example of
where you would use concurrent validation. You should agree up front with the Center exactly
what testing you are going to do. That should be written up in a protocol. You should then run
your one batch according to the rework procedure and write it up as an interim report that is
retained. Once you and the Center have agreed, you would release that reworked material. Your
concurrent validation report for this one batch would sit on the shelf, hopefully forever. If a similar
problem occurs where you would want to use that same rework procedure, then that would be
added on to the original protocol, and a second report should be written at that time. So, while it’s
not possible to document the consistency, and we all hope that we never have a lot of
opportunities to do rework, we should still capture all the additional testing and controls.
