Yingtai: Precautions for Sterilization Validation

Yingtai: Precautions for Sterilization Validation

1. There are three basic types of sterilization cycles. Choose according to the type of material to be sterilized.

Rigorous loading (vacuum) is suitable for substances that are easy to sterilize because air removal and steam penetration are highly effective for these substances. For example: open glassware and large-diameter pipes. A typical rigid item sterilization cycle requires a vacuum degree to be reached before steam is admitted to reach the set sterilization temperature.

Wrapped items (vacuum) are used for items that are difficult to sterilize because air removal and steam penetration are more challenging compared to rigid items. For example, capped empty bottles (glass or plastic), clean suits, long hoses/pipes, vent filters, portable containers with small inlets/outlets. A typical wrapped item sterilization cycle involves at least 3 vacuum draws before sterilization. After sterilization, the steam in the load is removed through vacuum.

Liquids (non-vacuum) generally contain liquid items that should not have a large vacuum degree, otherwise, the liquid will spill over. For liquids, the autoclave cycle is heated and cooled without vacuum. Steam enters the top of the chamber to displace air, which is pushed to the bottom of the chamber and expelled.

2.A variable to consider is whether to use fixed load or variable load configurations. There's a trade-off here between validation effort and operational flexibility- do you want to validate a wide range of load configurations to increase Production's flexibility in loading the autoclave?Here are some typical load configurations to consider:A fixed load/fixed position configuration means that any load to be sterilised will be placed inside the chamber in exactly the same way for every processing run. A diagram of the load configuration should appear in the Standard Operating Procedure (SOP) so that operators can reproduce the load for every processing run. This situation requires the fewest validation runs (3)but offers no flexibility in load configurations.A fixed load/variable position configuration means that the location of the load items in the autoclave can vary. Only a list of the items that can be in a load is required for the SOP. The validation runs must demonstrate positional equivalence by rotating the items from location to location during the test runs. lf positional equivalence is proven after three validation runs, then you can stop. A fixed load/variable position configuration gives operators flexibility in loading the autoclave. This saves time when loading large loads of numerous items of different types.A variable load configuration means that different combinations of items and/or numbers of any item(s) can be placed into the chamber. The validation runs must demonstrate that the cycle is adequate for both a maximum and minimum load configuration. The minimum load tests are done with only one item in the autoclave, that item being the load item demonstrated as being the most difficult to sterilise.

3.The choice of the Control used when sterilising liquids determines whether the load you are sterilising will pass all the acceptance criteria.M ore than one liquid Control may be needed to validate all the different types of bottles and liquids requiring sterilisation. Consider the following when choosing the Control for liquid cycles:The size of the bottle and its fill volume - the larger the bottle and the greater its volume, the harder it is to sterilise. The thickness of the glass -thicker glass is more difficult to sterilise than thinner glass.The viscosity of the liquid - the greater the viscosity,the slower the heat-up time, and the harder

it is to sterilise.

The liquid Control will ideally be the one that is the most difficult to sterilise (worst-case) and will be located at the coldest spot in the chamber (lower level near the front door or directly above the drain).

Don't be tempted to use a Control that is dramatically different from the composition of the load If the liquid Control takes too long to reach the sterilisation temperature, then the protein composition of the media in the rest of the load (which may have exceeded the desired temperature by the time the Control reaches the sterilisation temperature) may be denatured.If in doubt, perform preliminary studies using different liquid Controls to obtain information on the load's heat-up time sand F0-values.

The number of validation runs required for different types of liquids and bottles can be reduced by grouping liquids with similar viscosities, bottle sizes and fill volumes. Each liquid Control will have a unique maximum and minimum load configuration associated with it.Use procedural controls to ensure that the choice of liquid, bottle size and fill volume used for each Control, and its location in the chamber, are maintained during the validation runs and subsequent processing runs.