In response to additional ques on above subject:
STATEMENT: In the OQ phase; process parameters that yield acceptable product are found; process windows are determined (via DOE’s) and backed-up by statistical data. In the PQ phase, you recommend using worst-case settings – at the edge of the now-determined process window. While I can see that this is the most thorough way to ensure the process window is appropriately set, there are two questions:
Ques: Is this necessary in the eyes of the FDA or other governing bodies that you have run into? Or, is running the PQ at a nominal setting acceptable by the FDA and other governing bodies?
Ques: When validating a process that has many variables, are there rules of thumb to determining how many “worst case” settings or scenarios should be run? I can see how a machine could be forever in the PQ phase if we were constantly exercising worst case scenarios. I can’t imagine a business “making money” let alone shipping product if they are spending time in a constant PQ phase.
Ans: Again, I try to hold my initial PQs to 3-5 max. (this would not include the additional PQs required for additional tooling, different lots of resin, etc.) You combine as many as practical and can omit some if the patient risk is minimal to non-existent. You as the manufacture decide, and document your rationale. I sometimes use a matrix to combine, much like a factorial for DOE.
To add to my previous response (see previous blog) -- An Alternative to V&V of Press and Tools:
1. V&V the press as described (machine states plus other key settings / operations -- heating, cooling, pressure ...);
2. Do 1. with the next tool scheduled, with min of 3 PQs, to V&V the press and qualify the tool;
3. At completion of three PQs, et al, release that lot;
4. That will Validate the press (and qualify that tool);
5. Remove the press machine states and other press related elements from the PQ template, and leave those pertaining to the molded part (fill, stress (polorized light / destructive testing ...), dims, et al);
6. Do a min of 1 PQ for each new tool and/or each new lot of problematic resin as an addendum to the original Press/Tool V&V and after approval release that lot of molded parts.
7. Repeat for each new part until all tools are qualified.
8. Each part / tool PQ can be done as part of a normal run if no problems are anticipated, and when passed, signed off so the lot can be released.
9. Do the same with additional lots of problematic resins if an issue.
Of course, all the above assumes the same as mentioned in the previous blog, that there are downstream 1st articles / QC performed in molding and assembly, as further verification activities, documented (SOPs referenced, results included ...).
It further assumes that variations in input variables are basically well known and controlled. To the degree that they aren't, additional PQs may be required.
This is not as hard as it appears. And not that obstructive to a business' operation.
-- John E. Lincoln email@example.com