Stability chambers are built to artificially replicate conditions for those drugs that might be exposed in different environmental situations. Occasionally, it is used to accelerate the impacts of exposure to atmospheric conditions that may be hostile in any area where this medicine is stored.
Stability chambers work on the principle to retain the relative humidity (RH) and temperature of the chamber with the assistance of thermostats and water reserved in the chamber. According to the law of physics, the air can retain higher humidity with help of high temperatures in the chamber because the high temperatures increase the capacity of air to sustain higher humidity in certain situations.
To test the quality of the medicine under certain temperatures and humidity, a batch of the medicine of interest is located in a stability chamber that has maintained temperature and humidity for a specified amount of duration. Samples are scanned periodically for quality examination. The stability chambers used in the process need to be reliable and consistent because testing takes place over periods ranging from one week to six months, to one year or more.
Photostability is another type of stability testing, or how the drug is impacted when exposed to a certain amount of light and UV over time. Photostability testing examines whether undesirable changes occur to medicine when it is exposed to a combination of white light and UV light. For this test, stability chambers are required to fulfill certain guidelines and can emit the necessary light and UV over time.
In the field of the pharmaceutical industry, stability testing assists to provide information as to how the quality of medicine will adapt with time under a variety of environmental conditions including temperature, humidity, and light exposure. This testing must be accomplished before a drug arrives on the market.
The conditions for using stability chambers are highly specific and expect that the temperature deviates by no more than 2 or 3° depending upon the condition and humidity diverges by no more than five percent. Hence, chambers used for this type of testing must have low temperature and humidity variations that have been verified over a long period of testing. The temperature also needs to be consistent throughout the process. For photostability testing, they must be able to retain light exposure of more than 1.2 million lux hours and emit more than 200 watts of UV energy to samples. Unlike stability testing for temperature and humidity, photostability testing can be accomplished in very little time than can be one week and certain units can be programmed so that the light shuts off when the expected exposure has been attained.