Reagent Stability Testing of In Vitro Diagnosis

Stability research is an important content that runs through the entire IVD product development phase and supports the post-market research of IVD products. It is the basis for setting the product validity period. It can be used to judge the rationality of product production technology, formula selection, and packaging material selection. It is also As the basis for formulating product quality standards, stability research as an independent registration data is very worthy of our attention. What aspects should be considered in the process of stability research and what basic principles should be followed require in-depth discussion. Because the vast majority of IVD products contain biologically active ingredients, this article refers to the relevant requirements of the technical guidelines for biological product stability research (trial implementation), and elaborates some simple understanding of product stability research in eight aspects.

Plan

Before carrying out a stability study, it is necessary to formulate a stability study plan, including the determination of the samples used in the study, the conditions set by the study, the specific research projects, the duration of the study, how to conduct the transportation study, and the final analysis of the study results Wait. For our common IVD products, there are generally three aspects of stability research: long-term (real-time) stability research, accelerated stability research, and forced-condition stability research. Long-term stability research is the main basis for formulating product storage conditions and expiration dates. And mandatory stability studies are used to understand the stability of products under short-term deviations from normal storage conditions or extreme conditions. Of course, they can also be used as reference data for determining storage conditions and expiration dates. No matter which kind of stability study is done, it is necessary to verify the selected test method to ensure that it will not bring unacceptable test errors due to external factors such as personnel, time, environment, etc., and special attention should be paid to long-term stability studies. The selected test method should be consistent with the test method used when the product is released from the factory.

Sample

Generally, at least three batches of samples should be selected for testing during the stability study. The production process and quality requirements of the stability study samples at each stage should be consistent, and the quantity of each batch of products should at least meet the needs of the stability study. However, if the production batch size of the product may affect the actual performance of the product, it is recommended to use the mandatory condition stability study under the premise of controllable cost, such as: full-load mass production of three batches of products for product stability research. The packaging material of the product should be kept the same as the packaging material used in actual storage to verify whether the packaging material will affect the stability of the product.

Condition

Stability research should explore and optimize the research conditions according to the research purpose and the characteristics of the product itself, and the verification methods of other products should not be used in the same way. When selecting test conditions, full consideration should be given to the whole process of storage, transportation and use in the future, analyze and summarize various possible influencing factors in this process, and try to simulate the actual storage, transportation and use environment. Sexual research program. For example, for temperature research, the temperature conditions for long-term stability should be consistent with the actual storage conditions. The temperature in the mandatory condition test should be such that the performance degradation of the sample and the quality standard can be observed. The temperature conditions for accelerating the stability study are generally described. Between long-term and mandatory conditions, it is usually used when the reaction product may deviate from the reagent storage conditions in a short-term, such as whether the temperature exceeds the limit for a period of time during transportation will affect the performance of the product. Or for immunochromatographic products, the humidity requirements of the environment are relatively high, but if it can be proved that the packaging container of the product has good sealing performance, there is no need to study the stability of different humidity conditions. For another example, most diagnostic reagents contain liquid components. Under normal conditions, the reagent bottle should be placed upright, but if the reagent bottle is placed horizontally or inverted, the reagent liquid will contact the sealed part of the bottle cap and cause the liquid to seep, oxidize, or corrode. When the sealing ring leads to the chemical components in the sealing ring being incorporated into the reagents and causing performance changes, it is necessary to set up different reagent bottle placement states during the stability study for full evaluation, or identify such possible risks and take effective measures. The measures remind users not to horizontally or invert the product during storage or transportation.

Project

What should be done for stability? Generally speaking, we use the items specified in the “Technical Requirements for Products”. However, as a stability researcher, we shouldn’t talk about everything else and don’t understand the fundamentals. Therefore, we should fully consider product sensitivity when choosing a stability research project. Inspection items that may reflect product quality, safety, and effectiveness. For example, functional tests generally include sensitivity, specificity, repeatability, detection limit, linear range, etc. The reference materials used in the research process should be standardized materials. It is not recommended to use random selected clinical samples to avoid occurrence Random errors and systematic deviations of the evaluation results. For important inspection time points, such as annual inspections, all items should be verified. In the process of long-term stability research, it is found that the performance of the product is degraded or does not meet the standard. It is recommended to identify the different components of the product to clarify the cause of the performance degradation, and focus on observation when re-launching the stability study after the improvement. Its trend of change, evaluate the effect of improvement.

Time

With reference to the relevant guidelines and requirements for pharmaceutical biological products, the general principle of long-term stability study time setting is “test every three months in the first year, every six months in the second year, and every year from the third year onwards. Test once. If the validity period is one year or less, the long-term stability should be tested once a month for the first three months and once every three months thereafter”. However, the above suggestions cannot be copied and cited as the golden rule. It is still necessary to flexibly set the detection time point in the research plan according to the specific situation. For example, based on the preliminary stability research results, more intensive detection is performed for the time period when the product performance may change drastically. . In principle, the long-term stability should be as far as possible until the product fails. The mandatory and accelerated stability studies should observe that the product does not meet the product technical requirements. According to the current regulatory requirements, the stability study can continue to be submitted before the registration application, which means that the stability study may not be completely completed during the registration inspection and clinical trials.

Transportation

The transportation stability research stage should be completed on the basis of the planned cold chain storage and transportation conditions, and the transportation route, means of transportation, distance, number of transfers, time, conditions (temperature, humidity, vibration, etc.), packaging conditions ( Inner packaging, heat preservation measures, etc.), temperature monitor conditions (number and location of temperature monitors), etc. Simultaneously, it should be simulated under the worst conditions, during which the longest distance can be set, the temperature is extremely cold or extremely hot, and the cold chain during transit (considering the ambient temperature after the separation, the number of separations, the total time of separation, etc.), etc., The transportation stability study shall be conducted to confirm the transportation stability of the product under the specified storage conditions and the impact of transportation on the stability of the product under the specified storage conditions for a short period of time.
Result analysis
The stability study should be carried out in accordance with the prepared research plan, and the acceptable standard range (not lower than the quality standard in the product technical requirements) should be set in the plan to facilitate the final effective analysis of the research results. The results of the product stability study for different batches should have good consistency to verify the batch-to-batch difference of the product. The test results of the same batch of products at different times should be subjected to variation analysis to observe the trend of performance decline, and then determine the validity period and storage conditions of the product according to the set acceptance standards.

Application

The actual application of the results of the stability study is in the formulation of product instructions or product labels. The expiration date and storage conditions of the product should be clearly marked in the two materials in accordance with the existing regulatory requirements. At the same time, the precautions should also indicate the situations or behaviors found during the stability study that may bring risks to the product performance, such as: whether it can be frozen, whether it needs to be sensitive to light and need to be protected from light, whether it is humidity Sensitive needs dry environment etc. Products whose stability after opening is inconsistent with those before opening should indicate their storage conditions and expiry date after opening, and for freeze-dried products, their storage conditions and stability after reconstitution should be indicated.

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