The answer of EMAs Quality Working Party says, it is the applicant’s responsibility to select and justify the pilot batch size.
The joint CHMP and CVMP guideline on process validation (CPMP/QWP/848/96, CVMP/598/99) states that: “pilot-batch size should correspond to at least 10% of the future industrial scale batch i.e. such that the multiplication factor for scale-up does not exceed 10. For oral solid dosage forms this size should be at least 10% or 100,000 units whichever is greater* unless otherwise justified”.
The guideline does not dictate that the 10% figure should always be linked to the scale of manufacture of individual product presentations. In addition, it allows for departures from the guidance where this is justified. Further, the guideline does not preclude the use of bracketing.
Certain bulk products are used to produce a series of presentations, for example a bulk powder blend may be used to produce 50 mg, 100mg and 200 mg direct compression tablets with the same percentage composition. In such instances, as long as the applicant can demonstrate a satisfactory link between the pilot batch size used for validation and the routine production batch size, it will usually be acceptable to define the pilot batch size as 10% of the planned production scale for the bulk product. During the process validation study, the complete pilot scale bulk batch should be used to manufacture the individual presentations. The division of the bulk batch between the different presentations should also be justified.
*In the case of veterinary medicinal products, the minimum pilot size may be smaller than 100,000 units where justified.
Check your batch size to verify if it is (still) reasonable!
EMA/ Q & A List
EMA/ Q & A Batch Size