Process revalidation

how can we identify and justify how many years process revalidation?
Any guidelines?

Hi Aya, and welcome!

Process validation should have a lifecycle approach, instead of being considered as a single (periodic) event (FDA Guidance for Industry. Process Validation: General Principles and Practices ):

Stage 1. Process Design
Stage 2. Process Qualification
Stage 3. Continued Process Verification (CPV)

That being said, it is no longer expected by the health authorities to have a “revalidation” period; instead, it is expected to have a continued process verification program which will demonstrate if the process has remained in a validated state lot by lot.

Process revalidation would not be required if changes tot he process have not been made and the CPV program has demostrated the process has been maintained in a validated state.

I hope this is helpful.