Accelerated Aging Discussion
Posted by Frank Hild on Tue, Jun 02, 2009 @ 12:05 PM
Determining the effects of aging on a package/product in real time is a lengthy process that would severely delay market introduction of new products. Therefore, a standardized test methodology was developed to accurately evaluate the environmental effect of storage on a package/product during its expected usable shelf life. Accelerated aging, which subjects samples to elevated temperatures for specific periods of time, is used to simulate the effects of real-time aging and provides data which allows the manufacturer to accurately predict the effect of real-time aging on his package/product. A product can be released to market based upon successful accelerated aging of the package/product that simulates the period claimed for product expiration. (1 year, 2 years, etc.) Concurrent with the accelerated aging process, the manufacturer should still conduct real-time studies in order to substantiate the data generated during the accelerated aging process.
* Standard Test Method: ASTM F1980; Accelerated Aging of Sterile Medical Device Packages
Methodology: Accelerated aging techniques are based on the assumptions that the chemical reactions involved in the deterioration of materials follow the Arrhenius reaction rate function. This function states that a 10° C increase or decrease in the temperature of a homogenous process, results in approximately a two times or ½ time change in the rate of a chemical reaction.
Definition of variables:
AAR : Accelerated Aging Rate
AATD : Accelerated Aging Time Duration
DRTA : Desired Real Time Aging
AAT : Accelerated Aging Temperature
AT : Ambient Temperature
Q10 : Accelerated Aging Factor
Q10 = 2 - industry standard
Q10 = 1.8 - more conservative option
Equations:
Step 1. AAR = Q10^ ((AAT - AT) /10)
Step 2. AATD = DRTA / AAR
Example: Time duration calculation for accelerated aging of a medical product:
One year shelf study at 55° C, where ambient temperature is 22° C and Q10= 2
Equation Sample Data
AAR = Q10 ^ ((AAT -AT) /10)
AAR = 2 ^ ((55 - 22 / 10) = 9.85
DRTA = 1 year x 365 = 365 days
AATD = DRTA / AAR
AATD = 365 / 9.85 = 38 days
NOTE: 55° C and Q10 =2 are the most commonly used factors for medical devices and medical packaging components.
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