This is a continuation of last month’s Cleaning Memo. In that Cleaning Memo I discussed the criticality of cleaning for primary packaging equipment.
That this is important is evident from the fact that the principle involved (non-uniform contamination of the next batch) is mentioned in the FDA cleaning validation guidance. This month I will focus on issues related to limits and worst-case challenges. As discussed last month, one issue that makes primary packaging equipment critical is that it is possible that residues on some or all surfaces of the primary packaging equipment may preferentially transfer to a small portion (such as the first portion) of the next product packaged. It would be prudent to set limits based on this worst-case assumption (that transfer of residues can preferentially occur into a small portion of the next batch).