This Cleaning Memo is a follow-up to last month’s where we covered criteria for selecting swab sampling locations. This month we will cover how to appropriately document that selection criteria and process. I am not advocating a “best practice”; there are many ways to appropriately document the selection process, so we will cover some of the considerations.
First off all, it is most important that the criteria used for selection (such as those criteria covered last month) be either described or referenced in a high level document, such as a cleaning validation master plan (CVMP) or standard operating procedure (SOP). While it may be possible to skip this step and just have the criteria listed in each cleaning validation protocol, this will inevitably lead to inconsistencies in terms of applying the criteria from protocol to protocol. Failing to cover the criteria in a high level document also calls into question your firm’s commitment to consider such criteria on a consistent basis (from one situation to the next). For clarification, I am not saying that the same locations should be sampled in different situations; I am merely suggesting that the criteria selected for a specific situation should be selected from among the possible worst case criteria described in the high level document. I should also add that in a specific situation there may be one or more locations that would be unique and should be selected for sampling for that one situation (in addition to other selected locations).
The next step preferably is to establish documents with a swab sampling map for each equipment item (or perhaps for a group of items, such as “all 1000 liter liquid blenders”). If the document applies to a group of equipment items, the specific identification of covered equipment, such as the equipment number or ID, should be listed as part of the document. The “map” itself could be a schematic or a digital image of the equipment with specific locations to be sampled marked to assist in proper sampling. For example, those locations may be identified sequentially, such as A, B, C, and so on. In that same “swab sampling map” document there should also be additional information on each identified and marked location. That additional information should include a verbal description (such as left sidewall at air liquid interface), the type of residue to be sampled (such as API, detergent, or bioburden), and a short rationale of why that location is a “worst-case location (such as “juncture of two material”, “rough surface”, or “unique material of construction”). There may be other general categories that could be added, such as whether sampling is to be done after every batch or only at the last batch of a campaign (commonly called “changeover cleaning”). It may be most suitable to present this verbal information in tabular form to clearly separate the relevant information for each identified location (A, B, C, and so on). This document map should be a controlled document. As a controlled document, it should be updated and approved to reflect any changes in the equipment itself or in products made in the equipment.
Then, in a cleaning validation protocol, this document of the sampling locations can be either referenced (my preference) or reproduced (copy and paste). If it is referenced, then when residue limits are specified in the protocol, they should listed and be tied to the sampling locations (that is, A, B, C, and so on) in the document map. If it is reproduced, an additional column may be added to include the residue limit. In either case, there should be a reference to where the determination of the limit is documented.
As suggested, this is not a template to follow, but rather considerations to assist you in making appropriate decisions in how to document sampling locations. Finally, there may specifics of your cleaning validation practices that may require other variations consistent with GMPs.
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