Choosing the Right Equipment for Drug Stability Testing

In the pharmaceutical industry, stability testing helps demonstrate how drug quality changes over time under various environmental conditions, including temperature, humidity, and light. This testing must be done before the drug can reach the market.

To test the quality of a drug at a specific temperature and humidity, a batch of the drug of interest is placed in a Constant Temperature Humidity Chamber for a specified period of time. Samples are checked periodically for quality analysis. Because stability testing can span anywhere from a week to six months to a year or more, the stability chambers used must be reliable and consistent.

Another type of stability testing focuses on photostability, or how a drug is affected when exposed to certain amounts of light and ultraviolet light over time. For this type of testing, a stability chamber that meets specific guidelines and is capable of emitting the required light and UV light over time is required.

Complying with ICH guidelines requires stability chamber with consistent performance
Stability testing guidelines are outlined by the International Committee for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) and are followed by regulatory agencies worldwide, including the Food and Drug Administration (FDA), European Commission (EC), and Health Canada. Six ICH Guidelines (Q1A to Q1F) provide specific details for adequate testing. These guidelines are very specific, requiring that the temperature in the stabilization chamber not deviate by more than 2 or 3°C, depending on the conditions, and the humidity not deviate by more than 5%. Therefore, a stability chamber for such tests needs to have the low temperature and humidity excursions observed during prolonged testing.

The temperature also needs to be uniform throughout the unit. Stabilization chambers that use traditional non-directional airflow systems use fans mounted on top of the unit to push air down through wire shelves. When racks are filled with samples, this air flow is blocked, causing changes in temperature conditions throughout the chamber. This inconsistency may affect stability conditions and overall stability testing.

In contrast, a stabilization chamber that uses a horizontal laminar airflow system includes a positive-pressure feed chamber on one side of the chamber and a negative-pressure return chamber on the other side to create horizontal airflow directly across the surface of each shelf. Using this method means that even when the racks are full of samples, they receive a steady flow of conditioned air, resulting in optimal temperature uniformity throughout the chamber and across all samples. The horizontal laminar airflow system also increases the capacity of the stabilization chamber by ensuring temperature uniformity, even when the racks are full, enabling testing of larger sample batches.

Reliable unit will maintain performance during long-term stability testing
Samples can be tested in a stabilization chamber for a week, six months, a year or longer, depending on the type of testing performed. If one chamber fails, pharmaceutical labs could lose months of work and will be pushed backwards in their timelines, prolonging the time it takes for a drug to reach the market. Stability chambers used for stability testing in the pharmaceutical industry must be durable and rigorously tested for their long-term performance.

Additional features help pharmaceutical labs feel safe when using the stability chamber. For example, high and low temperature alerts can warn users when temperatures deviate. Even better, remote monitoring systems allow users to keep track of what's going on in the room even when they're not in the lab.

Requirements for Photostability Test Chamber

Photostability testing evaluates whether drug products undergo unacceptable changes when exposed to a combination of white light and ultraviolet (UV) light. Stability chambers used for this type of testing need to provide ideal light emission to meet the ICH requirements of Guideline Q1B - they must be able to maintain more than 1.2 million lux hours of light and emit more than 200 watts of UV energy to the sample. Unlike stability testing for temperature and humidity, light stability testing can be completed in as little as a week, and specific units can be programmed to turn off the light when the desired exposure level is reached.

One issue to consider when performing photostability testing is safety. Exposure to UV rays can cause damage to human eyes and should be avoided. A chamber with lights that automatically shut off when the door is opened will help prevent UV exposure and keep your workers safe.

Other potential uses
In the rare case that your pharmaceutical laboratory does not perform stability testing, the stability chamber can be used for other applications. For example, because they maintain a constant temperature and humidity, they are ideal containers for samples that need to maintain stablity conditions.

Stability testing in the pharmaceutical industry is a time-intensive investment, and selecting the right instrument should not be taken lightly. Stability chambers for testing the stability of pharmaceuticals under different temperatures, humidity and light need to be reliable, stablity and comply with ICH guidelines.