Peculiarities of confirmation of shelf life of medical devices

On every package of a medical product, we can always see a line with the shelf life or the date of issue and expiration date and can calculate this value ourselves. Why are different storage values sometimes declared for the same product? Why are some products not declared to have a shelf life at all? And how can we know for sure that during the time stated on the package, the MI will really be usable? We will try to answer these and other questions in this article.

What is the purpose of prescribing a time limit on medical devices?

The warranty shelf life of a medical device is the period of time specified by the manufacturer during which nothing will happen to the product and it can be safely used. Of course, there are many nuances here. And the most important is that this period is guaranteed under the right conditions of storage and transportation. If the conditions of storage of MI were ignored or the integrity of the packaging was violated, no one can guarantee that the product is suitable for use. Why? First, all medical devices are treated differently - some are sterile, some are not, and some are sterilized before use. The sterile ones inside are also categorized according to the sterilization method. It can be exposure to ethylene oxide (EO), gamma radiation (radiation sterilization R), steam and other methods, depending on the production technology and materials used. Secondly, exposure to moisture and temperature plays not the least role. Some products are stored only at low temperatures, for others, exposure to low temperature conditions is detrimental. And thirdly, it is important how the product is delivered to the end user, i.e. the method and conditions of transportation can certainly affect the final product. Therefore, these conditions are necessarily stipulated in the normative document for MI.

Choice of packaging

Confirming the shelf life of medical devices consists of several steps. And the first important one is the selection of the primary packaging. In order to protect the MI from environmental influences, the manufacturer develops and approves a specific packaging for each type of MI. And it is not just chosen because the manufacturer wants it that way. For sterile products, packaging is selected based on the requirements of the sterile barrier standard. For example, if your MI is being treated with ethylene oxide gas, the packaging must be gas permeable, but it must not allow microorganisms to pass through. And so on, depending on the manufacturing conditions, the raw materials used, and even the region where the MI is distributed. When a package is selected and tested for certain parameters, it is necessary to understand how long it can hold a sterile state. And in general, whether the medical device itself will not lose its properties over time. 

Stability test

To understand the lifetime of medical devices, the manufacturer subjects them to a stability test in their final version. It comes in accelerated and real-time versions. In the accelerated process, the MI in the final packaging is stressed by increased temperature and humidity. This happens according to certain rules, following international practices. There is a standard ASTM F 1980:2016 on accelerated mode, it should be used in determining the parameters and in general, follow its recommendations. Accelerated stability implies precisely compressed time frames. For example, if the shelf life of the product is defined as 3 years, the accelerated stability test is conducted in about 3 months. In real time, on the other hand, stability is tested for the entire declared 3 years. 

Real-time mode also implies that the intervals at which the MI will be tested are set longer. For example, with accelerated stability, we will test the product every month or even week, while in real time the first test will be conducted after 6 months. Of course, it depends a lot here on what raw material the product is made of. When there is a medicinal product in the composition, the approach changes completely. And for some forms of release, stability is only conducted in real time. 

Manufacturers always test this parameter in parallel in two modes. This is to ensure that the declared shelf life of the medical device is confirmed. And sometimes, based on the results of one of the modes, the shelf life of medical devices or storage conditions may be adjusted. That's why it's important that an MI comes to registration fully tested. Only a ready and complete stability report can ensure that the duration of suitability and storage conditions are correctly determined. 

Medical technology

The service life of medical equipment is defined in a different way. The equipment is subjected to cycles of reliability tests, whereby by counting and recalculating the manufacturer determines how long the equipment is guaranteed to last before it loses functionality. This means that, in theory, the equipment can last forever if used correctly. Therefore, the concept of "shelf life" for MT is not applicable. The terms "useful life of medical equipment" or "normative service life of medical equipment" are used. 

It is also important to maintain the equipment and replace components in a timely manner. The correct use of the medical equipment is described in the operating instructions. The manual also includes the conditions under which the correct operation of the equipment is guaranteed and which accessories can be used in conjunction with the MT. 

What to put in the file medical device

In the context of medical device registrationFor IMNs, the experts want to see in the dossier all reports confirming that the MI has been fully tested and the declared shelf life confirmed. For IMNs, the summary stability report must be accompanied by test reports confirming the results of the tests and providing full information on the series, standards and the manufacturer itself. For RCs, examiners accept an accelerated stability report, without real-time confirmation. For medical devices, the main report that confirms the life cycle is the MT technical test report. It should show reliability testing, in addition to the basic EMC, electrical safety and functionality tests. 

Naturally, the reports confirming the shelf life should be in addition to the instructions for use, the quality normative document and the layouts, since all these documents are considered together and the information in them should not allow for discrepancies.