Please see below for further details on this part of our quality assurance management.

Shelf life and long-term stability tests

Bios products have long shelf lives ranging from 3 to 10 years (corresponding to 36 to 120 months). Customers usually obtain batches from us with a remaining shelf life of 3-6 years.

Please note however: The expiry dates are valid only, if our products are stored in the customer laboratory as specified on the product label. All our products are issued with a dispatch label specifying storage conditions (usually just the storage temperature) and expiry date. In addition, each of our delivery parcels comes with a Bios-blue sticker reminding the recipient to avoid any disruption of the cold chain and promptly place the received goods into appropriately temperature controlled refrigerated storage. Bios keeps appropriately stored retention samples of each batch. This allows re-evaluation of product performance in case there are any respective customer complaints and to check whether or not the concerned product batch retained its full activity when appropriately stored. Shipping times to any of our destinations usually do not exceed 60 hours and do not have any adverse effect on our product activity as assessed many times. We regularly expose our products to simulated shipping conditions and then determine product activity. For such simulation tests we expose the shipping cartons for 60 hours to an ambient temperature of 25-33°C. The temperature in the inside of the cartons measured with a mini/max thermometer never rose beyond 25°C. Shipping simulation also includes tossing the cartons around and hurling them against a wall. About 20% of our long-term stability test results were obtained from such transport simulation test.

We determine the shelf life of our production batches by comparing the results of long-term tests with those obtained when the production batch was originally approved/released for sale. For example: For approval of a batch of mumps test slides the test results must exactly match the titer stated on the positive control, show a clearly negative result for the negative control, and show no interfering staining with the conjugate control. To validate the guarantied shelf life we test a retained sample of this batch of mumps slides again during the last month of expiry using the test reagent batches (positive and negative controls, conjugate) available at that time. The shelf life of the mumps slides is confirmed if the test results obtained at the initial batch release are confirmed. In this way we monitor and if required adjust the shelf life of our merchandise. Long-term tests are an essential aspect of our quality management. We therefore publish these results on our website.

What we call ‘long-term tests’ (LT ) are quality checks that we use to determine and assure the shelf life of our product batches. How we perform and evaluate the long-term tests does not differ in any way from the tests done for initial batch approval. The only difference is that the LTs are not performed at the beginning of a batch evaluation but rather at various intervals during and beyond the guarantied shelf life, more specifically within the shelf life (interval X), around the expiry date (interval Y), and after the expiry date (interval Z). If the test results meet the performance criteria of the batch as established at initial product approval we may extend the shelf live for the remaining stock of this batch and issue it with a new batch code and expiry date. Before this can happen however, such LT results must have been reproduced with at least another batch. Batches that have been issued with a 2nd shelf life can be recognized by the customer on the larger label stuck over the original label (more or less perfectly). We do not remove the old label to avoid any adverse effect on the quality of the product. At the same time the readily identifiable new label makes customers aware that this particular batch has been issued with an extended shelf life.

These shelf life extensions described above are principally possible because expiry date or product expiry are only technical terms. Shelf life and expiry are merely convenient classification (stock holding) criteria regardless whether stock administration is done by analog recording on file cards or digitally in a data bank. The activity of our products however, and this is what matters here, does not suddenly diminish at some point in time. The expiry date of a batch marks a point in time for the minimum shelf life. Therefore, principally all our product batches are potentially fully active for a longer time than indicated by the expiry date. We make use of such shelf-life extensions only with slow-selling batches.

We do not perform any long-term tests for products such as solid PBS buffer substance, blotting paper templates, embedding medium (1610, 161010), and cover slides (1700, 17200). These products cannot expire and therefore do not carry any pre-label with allocated batch number. Nevertheless, we allocate pro forma a shelf life of 10 years to these products, which merely serves convenient administration of batches in our merchandise data bank. Therefore, customers will receive these products with a dispatch label stating for this batch the pro forma expiry date, which is irrelevant in this case.

Special long-term data are automatically obtained also for all the test reagents used in the long-term stability tests of each product batch. We collect these data under the term ‘activity at re-use’. Each batch of a test reagent, such as conjugate, positive control, embedding medium, or cover slides that was successfully used in a long-term stability test of a product batch is automatically also OK. Each successful test confirms that all test components meet the required quality criteria. These data relate to reagents used within their shelf life because for our tests we only use reagent batches that have not expired. We are dealing with evaluation of ‘activity at re-use’ because these test components are integral part in the ongoing evaluation of product batches and long-term stability tests.

Besides selling in-vitro diagnostics (IVD) that Bios manufactures completely on their own, we also sell half-finished or finished products from other IVD manufacturers. However, all these goods are sold under the Bios name (e.g. immunofluorescence reagents under Bios and the tradename Biognost® for this product line). And this means that for all these products every single batch must pass the Bios performance validation and long-term stability tests. Therefore, the Bios guarantee of product quality applies both to the products manufactured in-house and to those we obtain from external IVD manufactures.

There also may be batches that fail a long-term test. If such batches are still within their guaranteed shelf-life we recall them from the market. If they are past their expiry date we are nevertheless critically evaluating the situation and review the assigned shelf-life. We perform additional long-term stability tests on current and subsequent batches to assess whether the earlier test result was just an outlier or whether the assigned shelf-life has to be questioned. Fortunately we are facing such situations only very rarely and with very few products when we have to spend such time and effort.

Last modification: 30.11.2020