DDL conducts both accelerated aging testing and real time aging testing to help establish shelf life and expiration dates for medical devices, packaging and products.
When establishing shelf life claims, it must be recognized that the data obtained from accelerated aging testing is based on conditions intended to simulate the effects of aging on and between the materials involved. The resulting ‘expiration date’ or shelf life from accelerated aging testing is considered a conservative estimate. Real time aging test results are used to verify accelerated aging evaluations and together are used to determine final shelf-life claims/values.
Accelerated Aging Test for Shelf Life Validation
Accelerated aging testing is based on a thermodynamic temperature coefficient formulated by J.H. Van’t Hoff that states “for every ten degree Celsius rise in temperature the rate of chemical reaction will double.” However, since this formula is based on rate kinetics of a single chemical reaction, not on packages made up of various materials, the direct extrapolation of this theory to the aging of packaging materials must be used with caution.
The FDA and the package testing industry believe Van’t Hoff’s theory is useful in defining and justifying accelerated aging testing services. Temperature selection for an accelerated aging study should be determined by the temperature that avoids unrealistic failure conditions such as deformation due to melting. Real time aging must be performed in conjunction with any accelerated aging study to correlate the results found during accelerated aging.
Real Time Aging Testing
Real time aging is performed in parallel with accelerated aging in order to support and verify accelerated aging conclusions. It is recognized that in some cases products are technologically obsolete before a real time aging project can be completed.
The FDA provides guidance regarding medical device shelf life determination and advises manufacturers to consider several parameters including chemical and physical. The European Medical Device Directive (MDD) requires all sterile medical devices to have an expiration date. Documented shelf life evidence must exist to substantiate shelf life claims made by the manufacturer.
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The use of Van’t Hoff’s Theory for medical device products and packaging materials is supported by the following references:
Hemmerich, Karl J., “General Aging Theory and Simplified Protocol for Accelerated Aging of Medical Devices” Proceedings MDM-West, January, 1997
Clark, Geoffrey, “Shelf Life of Medical Devices” Guidance Document, Division of Small Manufacturers Assistance, CDRH, FDA, April 1991
