Stability Studies 101
Pharmaceutical | PMTA | CBD
Stability studies or shelf-life studies are studies conducted on products to evaluate their shelf-life. These studies are important in ensuring that products are both safe and also that they meet their label claim over the course of their life.
Stability studies should be conducted for any product where a shelf-life is marked on the label to inform the consumer or patient when the product is safe to use.
There a number of ways to conduct stability studies, some suited better than others for particular product types. Samples are typically stored under fixed ‘conditions’ where the temperature and humidity are tightly controlled.
Long term studies: typically these studies run in ‘real-time’ for the intended duration of the product shelf life. So for a product with a 1-year shelf life, these studies would run over 1 year. 25°C ± 2°C/60% RH ± 5% RH
Intermediate studies: these studies are conducted for climatic regions where temperature and humidity are harsher than for others. These studies typically last 6 months where samples are stored at the following conditions: 30°C ± 2°C/65% RH ± 5% RH
Accelerated studies: these studies are intended to ‘fast-forward’ the degradation of the product through increasing heat and humidity to give a predicted shelf life. These studies typically last 6 months where samples are stored at the following conditions: 40°C ± 2°C/75% RH ± 5% RH 6 months
For each product, an appropriate specification should be set. What is appropriate for one product may not be appropriate for another and so whether you are testing a pharmaceutical tablet, medical device or CBD product, varying standards and considerations should be made.
Physical: Assessment of the physical properties of the product may be made such as the product appearance and pH which may change over time and indicate degradation or packaging interaction. Other tests may include uniformity contents and dose.
Chemical: Chemical testing is seen as the primary indicator of product degradation. Typically the main component or ingredient will be assayed (measured) to track its reduction over time. In addition to the main compound, a measurement of any related compounds or degradants is typically made.
Microbiological: It is important to consider the microbiological effect of the product and that microorganisms may pose to human health. Formulations high in water content may be particularly susceptible to microbial contamination and growth and over time unsafe levels of toxins may form. If the product contains anti-microbial compounds, the effectiveness of these should be measured as part of the stability study.
It is typically recommended that not fewer than 3 batches of each product are tested on a stability study. This number may vary depending on the industry, for example, for CBD products under Novel Food regulations it is recommended to test 5 batches of product.
Samples of each batch are normally tested at predetermined intervals throughout the course of the study. Typically, the following testing frequency is recommended for a 12 months study: study start, 6 months, 9 months, and 12 months. For accelerated studies, a minimum of; study start, 3 months, and 6 months are recommended.
Extrapolation of data
Typically, for regulatory submissions, applicants will submit data before the end of a study (i.e 12 months into a 24-month study). It is generally accepted that if no appreciable change in product characteristics are observed during the study, it is possible to extrapolate or predict a product shelf-life. This enables more timely submissions of regulatory data. Accelerated studies generally work on the principle that for every 10°C above room temperature, the product should degrade at double the rate (Arhanious Theorem)
It may be beneficial to consider the impact of forced degradation on the safety of the product. UV light and oxygen may be used to force the degradation of the product in a stress test to evaluate how the product is likely to perform to such stresses and whether an unsafe product is formed.
Stability studies are useful tools in the evaluation of product safety. Under certain regulatory frameworks; PMTA, pharmaceutical, and novel foods, they form a pivotal element of the regulatory submission process. Contact our team at Inter Scientific to see how we can help you. With fully validated test methods and ICH compliant, onsite storage, we can take away your regulatory burden and simplify the process.