Qualification of containers for cold storage of cytotoxic vials remains in the isolator of a centralized cytotoxic preparation unit

Introduction
Centralization of cytotoxic preparations in sterile isolator allows to use cytotoxic vials remains for several preparations. In the context of acquiring an isolator without a refrigeration system, a sealed transfer container, not connected to the isolator, was chosen for cold storage of remaining products. These residues are put into the pre-sterilized container containing eutectic plates. When not using the residues, the container is stored into a refrigerator. Upon using the residues, the container is sterilized. The aim of our study is to test the container’s sealing, maintenance of sterility, and temperature compliance over time.

Methods
Three transparent sealed containers of different sizes, intended for food preservation, were tested. During peracetic acid sterilization, the containers were checked for sealing, using peroxide detection strips to ensure that the sterilizing gas did not diffuse into the containers. Container sterility maintenance is checked using trypticase soy medium, introduced into each container inside the isolator, whose sterility is verified through a calibrated 1m³ air sample. Two positive controls are set up by introducing 100 CFUs of a referenced Staphylococcus strain: one control is placed in the incubator at 32.5°C, and the other control at 5°C with the test containers. Temperature maintenance is monitored by using a temperature probe inserted into the container with the eutectic plates. The container is initially stored in the fridge and then moved into the isolator after sterilization. Temperatures are recorded every 30 minutes for 3 hours.

Results
All containers passed the leak test. No microbiological contamination was observed for 37 days on the containers cold-stored. Container temperature readings showed an increase of 5.2°C, 3 hours after removal from the refrigerator.

Discussion/Conclusion
The seal integrity and sterility maintenance of our containers were found to be compliant. However, the temperature increase of the container does not allow its use, outside the refrigerator, for the entire production day, and the container must be returned to the refrigerator in the middle of the day. The development of containers without connection to the isolator, designed by manufacturers, could ensure better cold storage of cytotoxic residues.

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