Stability

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How stable are drugs, how are shelf lives/expiry dates of food (milk, cake, etc), drugs, and medical devices, such as a rapid diagnostic device (pregnancy device, rapid drug test device, etc) are determined?


The Food and Drug Administration (FDA) has strict rules on what is written on the packages of food, drugs, and medical devices. Before expiry date of a product is determined, pilot lots of the product must be manufactured following the exact  manufacturing procedures. The performance data of these pilot lots are tested for collecting the product's performance data. Stability or shelf life under certain storage conditions of these products are collected. There are two ways to conduct a stability study. One is accelerated stability study and another is real time stability study. The acceleration is usually achieved by increased temperature condition, therefore, such studies are called temperature accelerated stability study and real time/real temperature stability study.


Real Time - Real Temperature Stability Study


Because most FDA regulated products have confined storage temperature, the real time/real temperature stability study may be confined to the proposed storage temperature. The FDA requires that real time/real temperature stability study be made for all products that has an expiration date on the label. To do so, the manufacturer or a contractor testing lab obtain three pilot lots of the product and place them at the recommended storage temperature condition and monitor how the products degrades. The time for the first lot of product that falls out of the specification is established as the shelf-life of the product.


Temperature Accelerated Stability Study


How is temperature accelerated stability study designed and how are the data analyzed

FDA Guideline

Arrhenius Treatment

The stability data from the accelerated stability studies can be treated according to the Arrhenius equation. STABILITY SYSTEM computes the activation energy and the pre-exponential factor as well as the rate constants and the expiry dating periods for several temperature ranges of interest to the pharmaceutical system.

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