All products such as cosmetics and pharmaceuticals decompose with time. The purpose of stability testing cosmetic products is to ensure that a new or modified product meets the intended physical, chemical, and microbiological quality standards while also ensuring functionality and aesthetics when stored under appropriate conditions.
Cosmetic and personal care products that are intended for storage at room temperature have two options for stability testing, Real Time and Accelerated Testing. Accelerated Stability testing is based on the idea that a product that is exposed to extreme conditions will perish at a faster rate than a product stored and used under normal conditions. A general standard for accelerated testing, based on the Arrhenius Equation, is:
10 weeks at 45°C is equivalent to 1 year at ambient (~21°C) temperature.
Types of Stability Testing
Stability tests can be conducted in real time or under accelerated conditions and should address the stability of a product under appropriate conditions of storage, transport and use.
When testing a product for aesthetic and physical stability there are many characteristics to look for that will determine if the product is still of good quality over the designated use time. These include color, odor / fragrance, pH value, viscosity, texture, flow, and emulsion stability (signs of separation); microbiological stability tests which evaluate the degree of contamination with bacteria, mold, and yeast; and packaging stability tests which evaluate the impact of packaging on the contained product.
Packaging & Stability Testing
Packaging can directly affect finished product stability because of interactions which can occur between the product, the package, and the external environment. For example, product constituents may be absorbed into the container or may chemically react with the container. In addition, the container may not fully protect the product from the adverse effects of atmospheric oxygen and/or water vapor, or volatile product constituents (e.g. fragrances) may evaporate through the container.
Is Stability Testing Mandatory?
Stability testing is crucial to ensure your product is safe, of high quality, and remains functional. We do not recommend launching a product without first conducting this test. Manufacturers may require you to have this test conducted, especially if you are bringing a new product to market. If you are planning on selling your product in major stores, many stores will require you to have documentation of the shelf life.
Over the Counter products must undergo Stability Testing, and this is required by the FDA.
Stability testing can get expensive. Launching a new product is an expense. Prices for these cosmetic tests, range from provider to provider. Unfortunately, quality and efficacy also differ between providers. We recommend going to a laboratory to get your testing done.
The lab is most likely going to follow FDA Q 1 & (R2) of New Drug Substances and Products Guidance. You will want to make sure your provider conducts the USP 61 & 62 (United States Pharmacopeia) regulations as a part of their test. The purpose of this is to determine if there is any yeast or mold present in the sample.
There is a kit that can be purchased and used to reduce costs of the testing, but it is not legitimate because it does not follow the USP 61 & 62 standard protocols.