Many items need to be sterilized for aseptic processing, including stoppers, filler change parts, utensils and more, so for ease of operation it is common to maintain an inventory of ready-to-use parts in the aseptic core. Unfortunately, I’ve seen this taken to the extreme, with many sites essentially becoming a ‘warehouse’ of pre-sterilized items, with hold times as long as a month…
Long hold times have their advantages in terms of operational flexibility, but I’d argue against them from an aseptic processing perspective. In fact, I’d say that an aseptic warehouse of any size is just about the worst idea ever. The packaging for the sterilized items may be integral, but the additional handling required to keep them in the aseptic core for an extended period is always risky. Unfortunately, the practice of establishing a warehouse is all too common. It simplifies the planning process and allows for easy schedule changes because all of the required items are already available. What is sacrificed for all this convenience is the ability to maintain environmental conditions and item sterility. Don’t forget that all rooms, surfaces and items should be sanitized on a frequent basis, which includes storage areas and stored items.
The best approach to material supply in aseptic and clean filling is to adopt a ‘just-in-time’ approach by maintaining minimal inventory in the aseptic core. When items must be stored, it’s important to minimize the risks. The key here is to have an effective wrapping system. I prefer press-sealed bags, which are widely available and have a porous side for air/condensate/steam exchange. A much less capable wrapping technique that I’ve frequently seen is covering items in paper or cloth sheets that are then tied or taped to offer some measure of post-sterilization protection. Such wrapping is perfectly acceptable for birthday presents, but it’s too variable for aseptic items that are to be held sterile for any length of time. The integrity of the final package is nothing like that of press-sealed bags. They may be inexpensive but that does not justify their use. When it comes to validating hold times, the only method I believe appropriate is associated with aseptic fills: you hold the items in the aseptic core and then use them in a process simulation (media fill test). If the media fill test works then you’ve confirmed the acceptability of the hold time. You can schedule the media fill a day or two longer than the actual hold time you intend to use routinely, bearing in mind that the hold period should always be minimized as much as possible.
Establishing hold times via sterility testing of wrapped items is a much less appealing approach. The manipulations involved in sampling and testing these materials are very different from the methods used for testing the product itself and have the potential for false-positive results. I would set the hold time requirement for all products, both aseptic and terminally sterilized, using the results from the validation tests. However, it’s important to understand that the media fill test does not include every permutation of component or equipment – another argument against the gift-wrapping approach to sterilization component protection, where every item will be wrapped differently. Applying consistent wrapping methods to all items enables the firm to use the same validation data across the board.
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