Shelf life testing is part of the pre-production development steps. Labels on medical devices are required to have an expiration date, and this date must be based on evidence. At the expiration date, the quality and functionality of the product fulfil the specifications. On this website, we give some information about shelf life testing.
Samples
The number of time points and the type of tests must be determined to determine the required number of samples. All samples should be representative of commercial/clinically used products. Different sets of samples must be prepared (time 0, 6 months, one year, two years, etc) depending on requirements. As a starting point, the tests done during the validation of the process and packaging are a good start to test the shelf life. Examples are dimensions, mechanical strength, chemical stability, seal- and packaging integrity.
The total number of time points x number of samples per test must be doubled if both real-time and accelerated testing is done. Real-time testing is always required, while accelerated testing is optional.
Accelerated Shelf Life Testing
Accelerated shelf life testing aims to simulate the product’s ageing process over a shorter period, allowing for predictions about its stability under normal storage conditions.
- Determine the target shelf life.
- Define accelerated storage conditions: This typically involves elevated temperature and humidity levels. The chosen conditions depend on the stability of the product at these temperatures and influence the acceleration. The accelerated time points can be calculated using the Arrhenius equation.
- Store the products in these conditions, usually in a temperature and humidity-controlled stove.
- Test the attributes as defined in the protocol, at the required time points.
Real-Time Shelf Life Testing
A set of samples per time point is stored in storage conditions that are expected to be representative of normal conditions. If the storage conditions are ambient, the samples should be stored in ambient conditions, including temperature and humidity changes. The real-time ageing of samples should be done in the environment, it will be normally stored in. So ageing in a freezer, when stored in a freezer.
Logging the temperature and humidity while storing the samples and putting the results in the shelf-life summary report is always advised.