|
Sterile Barrier System (SBS) expiration dating
A thorough understanding of ISO 11607, parts 1 and 2, is instrumental in ensuring product efficacy and ultimately, patient safety. This article addresses four basic aspects of sterile barrier system expiration dating:
- Relevant definitions
- Performance testing vs. stability evaluation
- Real time vs. accelerated aging
- Suggestions for expiration dating evaluations
Definitions
A package stability evaluation demonstrates that the sterile barrier system maintains integrity of specified critical characteristics over time. Package stability/expiration dating refers to the indication of the date by which the product should be used, expressed at least as the month and year. MDMs should consider that if the expiration date is based on product performance, the date should reflect the effectiveness of device stability, which would limit the labeling to the shorter of the two.
Performance testing vs. stability evaluation
It is critical to understand the difference between performance testing and stability evaluation, as they can be interpreted quite differently. Performance testing evaluates the interaction between a packaging system and the product in response to stresses imposed by the manufacturing, sterilization, handling, storage, and shipping processes and environments. Stability evaluation can demonstrate a packaging system's ability to maintain an acceptable level of its critical characteristics after exposure to specified sterilization cycles and time (aging). Stability testing is often part of an overall packaging validation program that uses various physical test methods to evaluate the affects of aging on various package attributes.
Accelerated aging (AA) should be thought of as a conditioning mechanism of the package assembly. Often device manufacturers encounter problems resulting in failures which are associated with the manner in which the AA conditioning was conducted. MDMs should consider whether failures experienced during the AA conditioning are actual failures that can be experienced during real time aging or more importantly during real world scenarios.
Some of the critical attributes to consider in stability evaluation include (but are not limited to): microbial barrier properties, performance-related properties of materials, seal strength, and seal integrity of the package system.
Real time vs. accelerated aging
Aging should be done using a real time method. Accelerated aging (AA) data is acceptable provided it is started in parallel with the real time test sequence. As stated in the ISO 11607 standard, stability testing via AA protocols shall be regarded as sufficient evidence for claimed expiry dates until data from real-time aging studies are available.
MDMs should review the information readily available on the subject of conducting stability test sequences. ASTM 1980 is the most widely used document as it is the standard guide for accelerated aging of sterile medical device packages. There are also many opinions in terms of the sequence of events used to conduct a stability evaluation.
Suggestions for expiration dating evaluations
Consideration should be given to worst case as specified for sterilization cycles, as well as the number of exposures possible in the everyday production environment. Ask your packaging material supplier for standardized stability data on commonly used packaging materials.
If you use a month/year labeling format (i.e. 10/06), consider adding one additional month to your study (e.g., for 24 month evaluation, actually test 25 months) to ensure adequate evaluation.
The controversial topic of package/material stability evaluation has generated some great debates and articles from industry leaders. Some common discussion points include AA temperatures with or without humidity in the conditioning cycle, and pre/post distribution simulation of accelerated aged samples. Although each MDM must ultimately define which variation best suits their particular application, the following articles can help broaden your knowledge base on this subject:
The Need for Specificity in Accelerated Aging
Glen Petrie, Eastman Chemical Company
MD&DI—October, 2006
Sterile Packaging: the Facts of Shelf Life
SPMC
Medical Device Network—March, 2006
Demystifying Medical Device Package Validation
Scott Levy, DDL Inc.
P&MPN—November, 2004
About the author
Randy Troutman is Oliver Medical's technical director. He is a member of the Institute of Packaging Professionals medical device packaging committee and the Association for the Advancement of Medical Instrumentation (AAMI) packaging working group ISO/TC 198. Troutman joined Oliver in 2006, having worked previously for Smith & Nephew, Medtronic, and Kimberly Clark.
|
