Stability testing is one of the most commonly deferred items in a new product launch. The formulation is finalized, the packaging is selected, the launch date is set — and the stability program gets pushed to “after we launch.” The logic is understandable: stability data takes time to generate, and the product needs to get to market.
The problem is that an expiration date without supporting stability data is, at best, an educated guess and, at worst, a compliance liability. For FDA-regulated products, the expectation is that expiration dates are supported by data. For products sold in international markets, stability data requirements are often explicit and mandatory. And for any manufacturer who cares about product quality, stability data is the only reliable way to know whether the product you’re shipping today will still meet its specifications on the day a consumer uses it.
A stability program measures how a product changes over time under defined storage conditions. The parameters you test — potency, microbial limits, physical appearance, moisture content, pH — depend on the product type and the failure modes that matter for that product. A probiotic supplement degrades differently than a liquid botanical extract. A tablet with a moisture-sensitive active ingredient has different stability concerns than a hard capsule with a stable mineral.
The goal is to understand the product’s shelf life: the period during which it remains within its established specifications under the intended storage conditions. That shelf life becomes the basis for the expiration date on the label.
For dietary supplements, FDA doesn’t mandate a specific stability testing protocol, but the agency expects manufacturers to have a scientific basis for their expiration dates. The most defensible basis is real-time stability data — data generated at the intended storage conditions over the full shelf life period. Because generating real-time data takes as long as the intended shelf life (typically 1–3 years for supplements), manufacturers typically use accelerated stability data to support initial expiration dating, with real-time data generated concurrently.
ICH Q1A(R2) is the international guideline for stability testing of new drug substances and products, developed by the International Council for Harmonisation. While it’s technically a pharmaceutical guideline, it’s widely used as a reference framework for dietary supplement and food stability programs because it provides clear, scientifically defensible protocols.
The guideline defines three primary storage conditions:
The relationship between accelerated and real-time stability is based on the Arrhenius equation — the principle that chemical reactions proceed faster at higher temperatures. Accelerated stability data at 40°C/75% RH for 6 months is generally considered supportive of a 24-month shelf life claim, though this relationship varies by product type and degradation mechanism. For products with complex degradation pathways — botanical extracts, probiotic supplements, products with multiple active ingredients — the accelerated-to-real-time relationship may not be straightforward.
ICH Q1A(R2) is a reference framework, not a mandatory requirement for dietary supplements. Requirements vary by product category and market — consult a qualified regulatory expert for your specific situation.
A stability protocol should be written before the first stability samples are placed. The protocol defines: which product lots will be tested, which storage conditions will be used, which time points will be tested, which parameters will be measured at each time point, and what the acceptance criteria are for each parameter.
Time points matter. A stability program that tests only at 0 months and 24 months gives you limited information about when degradation begins. Standard time points for a 24-month program are 0, 3, 6, 9, 12, 18, and 24 months for long-term testing, and 0, 3, and 6 months for accelerated testing. Testing at intermediate time points lets you identify the onset of degradation and understand the degradation rate.
The parameters you test at each time point should be driven by the product’s known or anticipated failure modes. For a probiotic supplement, CFU count is the critical parameter — you need to know whether the probiotic remains viable throughout the shelf life. For a vitamin C supplement, potency is critical — ascorbic acid is sensitive to heat, light, and moisture. For a liquid product, microbial limits and pH may be the most important parameters.
Don’t test everything at every time point. A stability program that runs a full panel of 20 tests at every time point is expensive and generates more data than you can effectively analyze. Focus each time point on the parameters most likely to change, and run the full panel at the beginning and end of the program.
Stability is not just about the formulation — it’s about the formulation in its packaging. The container closure system affects moisture ingress, oxygen exposure, and light exposure, all of which affect product stability. A stability program should use the same packaging that will be used for the commercial product, or packaging that has been demonstrated to provide equivalent protection.
This is a common mistake: running stability studies in one packaging configuration and then changing the packaging before launch. If the packaging changes significantly — different container material, different closure type, different desiccant — the stability data from the original packaging may not support the expiration date for the new packaging. Any significant packaging change should trigger a stability assessment to determine whether new stability data is needed.
The output of a stability program is a dataset that supports an expiration date. The expiration date should be based on the earliest time point at which any tested parameter is predicted to fall outside its specification, under the intended storage conditions.
For a product with a 24-month intended shelf life, you need either 24 months of real-time stability data, or accelerated stability data that supports a 24-month claim with real-time data being generated concurrently. If the real-time data at 12 months shows unexpected degradation, you may need to revise the expiration date — which is why initiating stability testing before launch, rather than after, gives you time to respond to unexpected results.
At Aurora TIC, we help manufacturers design stability programs that are scientifically sound, operationally practical, and aligned with the regulatory requirements for their product categories and markets. The right protocol depends on your product, your packaging, your intended markets, and your quality system maturity — but the framework above is the right starting point for any manufacturer building a stability program from scratch.