HUMAN DRUG CGMP NOTES EXCERPT

December 1998

Is testing rinse solution alone enough to support residue determinations for cleaning validation?

Reference: FDA Guide to Inspections of Validation of Cleaning Processes, July 1993

While it is understood that rinse samples are capable of sampling larger surface areas, particularly ones which are difficult to access, for the purposes of cleaning validation, rinse samples alone would not be acceptable unless a direct measurement of the residue or contaminant has been made. One disadvantage of rinse samples is that the residue or contaminant may not be soluble or may adhere to the equipment. Some firms use both swab samples, where feasible, and rinse samples during the course of their cleaning validation.

For routine equipment cleaning after validation, some firms may be able to justify use of rinse samples to demonstrate the process continues to consistently clean the equipment.

FDA has compared rinse samples to that of a "dirty pot analogy." When evaluating the cleaning of a dirty pot, the rinse water is not what is looked at to see if the pot is clean.

The purpose of cleaning validation is to demonstrate that a particular cleaning process will consistently clean the equipment to a predetermined limit; the sampling and analytical test methods should be scientifically sound and provide adequate scientific rationale to support the validation.