Nutrasource Blog

Common Stability Testing Questions for Natural Health Products (Canada) and Dietary Supplements (U.S.)

Posted by Kevin Yan, M.Sc., VP Certifications & Analytics on Wed, Nov 20, 2019

As a contract research organization (CRO), we field many inquiries about stability storage testing here at SGS Nutrasource. Despite being extremely important, analytical product testing for stability and shelf-life is often overlooked. Keep reading to find our analytical team’s answers to the most commonly asked questions about stability storage testing for different dosage forms.

What is an accelerated stability test condition?

Accelerated stability test conditions as defined by the International Conference on Harmonization (ICH) are "studies designed to increase the rate of chemical degradation or physical change of a drug substance or drug product by using exaggerated storage conditions as part of the formal stability studies". The common storage conditions for an accelerated stability test condition can be found as prescribed in the ICH Guidelines for Stability Testing.

Can you perform stability testing for a physical, chemical and microbiological stability study?

Using it’s network of specialty laboratories, SGS Nutrasource can perform physical, chemical and microbial testing for stability studies under both accelerated and real-time conditions for a variety of products and matrices.

What is long-term stability testing?

Long-term stability testing is defined by the ICH as "stability studies under the recommended storage condition for the re-test period or shelf life proposed (or approved) for labelling". This type of testing is also referred to as room temperature or real-time stability storage condition testing.

The storage conditions are commonly 25°C +/- 2 degrees and RH of 60% +/- 5%. However, at times 30°C and 65% RH storage conditions can be substituted. This depends on the product or compound being testing, as well as the zone you are contemplating having the product sold in. These zones are also stipulated in the ICH Guidelines for Stability Testing.

How many lots of product do I need for accelerated and long-term stability testing?

Typically, between 1 and 3 lots of each product stored in finished packaging are required to be placed on stability. This depends on what stage of the product lifecycle your product is at, but ICH guidelines recommend 3 lots.

Regardless, we strongly urge you to consult with the applicable regulatory authority in your region to find out what specific requirements they may call for.

What time points do I need to test my products at?

Proposed stability testing should show results after 0, 3, 6, 9, 12, 18 and 24-months storage for long-term testing, and 0, 3- and 6-months storage for accelerated testing. However, if you feel your product can achieve a longer shelf life you could consider longer time points for long-term stability testing (i.e., 36, 48, 60 months).

What should a stability testing program’s conclusion contain?

A stability testing program should have a conclusion as to how the product was tested, what the result was and how long its shelf life should be (all based on the testing).

Additionally, a stability testing protocol should be created at the beginning of the stability testing program that states the parameters of the testing program, the product specifications, what is expected to be tested, and when testing should occur.

In a 24-month stability study, what are the critical time points?

For long-term studies, the frequency of testing should be frequent enough to establish the stability profile of the product. For products with a proposed shelf life of at least 12 months, the testing frequency at the long-term storage condition should normally be every 3 months over the first year, every 6 months over the second year, and annually thereafter through the proposed shelf life. If the product matrix is a unique formulation, testing frequency can be increased in order to better determine the exact stability characteristics

At the accelerated storage condition, a minimum of three time points, including the initial and final time points (e.g., 0, 3 and 6 months), from a 6-month study is recommended. Increased testing should be conducted where an expectation exists that results from accelerated testing and is likely to approach significant change criteria.

Can the testing of stability samples be matrixed?

One common question is whether the testing of stability samples can be matrixed in order to get costs down, yet still conduct a legitimate study. ICH guidelines recommend that for reduced designs, such as matrixing or bracketing, this approach can be applied if you can justify the matrix design.

Your stability schedule should be designed so that a selected subset of the total number of possible samples for all combinations is tested at a specified time point. At a subsequent time-point, another subset of samples for all combinations should be tested.

The design assumes that the stability of each subset of the tested samples represents the stability of all samples at a given time point. You must be able to identify the differences in the samples for the same product, covering different lots, strengths, sizes of the same container/closure system and different container/closure systems.

SGS Nutrasource provides stability testing services for a wide variety of product types. Contact us today to learn more about our capabilities and stability testing.


Kevin-Yan-cKevin Yan, MSc, is VP of Certifications and Analytics at SGS Nutrasource, with over 12 years of experience in natural health products and product testing. Kevin has helped hundreds of clients prove that their products are safe and effective for regulatory bodies as well as analytical testing required for research projects, release testing, and product formulation.

Topics: Product Testing & Certifications, Dietary Supplements/Natural Health Products