Determining a product’s lifecycle by estimating its shelf life is an important development step that needs to be analyzed prior to market launch. Shelf life is a natural process of an item’s decay over time. A simple way of examining shelf life is by placing the item in a controlled environment and checking its status periodically over time. This method is known as a real-time aging study. Since some items may be stable for very long periods of time (years, or even decades) without noticeable degradation, it is highly desirable to speed up the process. The environmental conditions that an item is exposed to are large factors in how quickly decay can occur. The main method used to accelerate this decaying process is exposing the product to high temperatures. The test methods associate an increase in heat with an increase in decay rate. This allows a shelf life test to occur over a much shorter period of time, allowing for expedited product launches with a confident assurance of shelf life.
Before starting any such testing, one must define the failure criteria. For pharmaceutical items, potency is usually the biggest deciding factor. As the product ages, it can lose potency to the point where it is no longer functional. When conducting the inspection of the product, it is also important to make sure the package is not compromised. A white plastic bottle can discolor or become brittle over time and may make the contents unsellable, even though the product itself is still useable. For a sealed pouch, it is possible that the seals could degrade and cause the product to lose sterility.
The failure mode must be broken down to the point where an inspection test can be designed, with a set number of planned inspections to take place throughout the aging study. The amount of material required per inspection should be multiplied by the number of planned inspections, and must all be included at the start of the aging test. At regular intervals, a sample of the product is taken out of the aging chamber and inspected agai
nst the acceptance criteria to determine if the amount of time passed constitutes a loss of product integrity. If the inspection is not destructive (such as visual inspection), the product can just be placed back into the aging environment and then reinspected at a later date. However, if the inspection testing is destructive (such as bubble leak), the product quantity used for the aging test must be enough to accommodate the additional periodic inspections without running out of material before the end of the study.
The end goal of accelerated aging is to determine the product’s usable shelf life based on scientific study, without having to wait for the real time aging to complete. While results might vary for different materials, this can shave months or even years from the product launch process.