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When do you need a drying step?

ISO 17664[1] specifies that ”where drying is necessary, at least one verified drying method shall be specified.” FDA provides more detailed information on the importance of drying steps following different stages of processing[2] as outlined below.

One important merit of adding a drying step following processing is that active device drying may reduce or eliminate recontamination. This is especially important for unwrapped devices that are processed by high-level disinfection or liquid chemical sterilization because these devices will be wet at the end of reprocessing. Consequently, FDA states that labeling should recommend a drying procedure after processing and before storage to eliminate moisture that can support the survival of contaminating microorganisms2.

However, drying is not only important following high-level disinfection or liquid chemical sterilization. Moisture remaining on wrapped, or contained products, after sterilization can compromise the package integrity and performance by impairing the sterile barrier properties of the packaging materials and the effectiveness of the seals. Therefore, FDA states that labeling should specify a validated minimum drying time for terminal sterilization methods for wrapped or contained devices2. Consequently, when validating steam sterilization parameters drying time should always be evaluated alongside the inactivation of microorganisms.

A final important consideration is mid-process drying such as drying after cleaning. Moisture that remains on devices following cleaning may interfere with subsequent microbicidal processes. Additionally, processing following cleaning may be delayed, which could again cause recontamination of cleaned devices. Therefore, labeling should recommend an intermediate and effective drying step prior to any delayed sterilization2.

In summary, whether for preventing recontamination, preventing package integrity loss, or preventing interference with subsequent microbicidal processes, a drying step is important after each stage of processing.

[1] ISO 17664:2017 Processing of health care products – Information to be provided by the medical device manufacturer for the processing of medical devices.

[2] FDA: 2015 Reprocessing medical devices in health care settings: validation methods and labeling – guidance for industry and food and drug administration staff