Drug stability refers to the ability of raw materials and preparations to maintain their physical, chemical, biological and microbial properties. The purpose of the stability study is to study the change of the properties of the drug substance or preparation over time under the influence of temperature, humidity and other conditions, to provide a scientific basis for the determination of the production, packaging, storage, transportation conditions and validity period of the drug, and to ensure the stability of the drug in clinical use. safety and efficacy.
Test methods for stability studies: long-term test, accelerated test and impact factor test.
Long-term testing is carried out under the storage conditions specified for marketed drugs. The purpose is to investigate the stability of the drug during transportation, storage and use. It can directly reflect the stability characteristics of the drug and is the basis for determining the validity period and storage conditions.
Accelerated tests are performed under abnormal conditions. The purpose is to study the stability of drugs by accelerating the rate of chemical or physical changes of the drug in commercial packaging. The purpose is to simulate the stability of research drugs under short-term abnormal conditions that may be encountered during transportation and storage, and to preliminarily predict the long-term stability of samples under specified storage conditions.
1. How to test drugs in a stability Test Chamber
The testing of influencing factors is carried out under harsh conditions. The purpose is to understand the factors affecting stability, possible degradation pathways and degradation products, and provide basis for preparation process screening, packaging material and container selection, and determination of storage conditions. At the same time, it provides a basis for the temperature and humidity conditions that should be used in accelerated tests and long-term tests, and also provides a basis for the selection of analytical methods.
Both temperature and humidity tests are impact factor tests. Generally, the test substance of the drug substance is placed in a suitable container (such as a weighing bottle or a Petri dish) and spread into a thin layer ≤ 5mm thick, and the loose bulk drug is spread into a thin layer ≤ 10mm thick for testing. For oral solid dosage forms, generally smaller dosage units are used, the inner packaging is removed, and dispersed into a single layer under suitable conditions. If the test results are inconclusive, two additional batches of samples should be tested.
2. Drug temperature and humidity test in the stability Test Chamber
1. High temperature test
The test product was placed in a sealed clean container and placed in a stable room at 60°C for 10 days, and samples were taken on the 5th and 10th days to test relevant indicators. If the test product changes significantly, perform the test in the same way at 40°C in a stabilization chamber. If there is no significant change at 60°C, no 40°C test is required.
2. High humidity test
Place the test product in an airtight container with constant humidity at 25°C, RH70%±5% for 10 days, and take samples for testing on the 5th and 10th day. Test items should include hygroscopicity and weight gain items. If the weight increase of hygroscopicity exceeds 5%, the test shall be carried out in the same way at 25°C and RH75±5%; if the weight gain of hygroscopicity is less than 5%, and other inspection items meet the requirements, the test shall not be carried out. Liquid formulations are not eligible for this test.
