What Is Stability?
Stability carries two distinct meanings depending on the product group. In FURNITURE, stability means resistance to tipping over: loads defined in the standard are applied to the product at defined points, and whether it tips is observed. In COSMETIC AND PHARMACEUTICAL PRODUCTS, stability is monitoring under controlled temperature and humidity conditions whether the product retains its physical, chemical and microbiological properties over its shelf life.
Purpose of Stability
In furniture, the purpose is to verify the product does not tip over under foreseeable use, particularly children climbing on it — tipped-over cabinets and TV units are a serious source of injury. In cosmetics and pharmaceuticals, the purpose is to support the declared shelf life and storage condition with data.
Which Products Is Stability Applied To?
- Cabinets, bookcases, chests of drawers and TV stands
- Tables and chairs
- Cosmetic products (cream, lotion, shampoo)
- Pharmaceutical formulations and packaged products
- Food supplements
In Which Sectors Is Stability Used?
Standards Related to Stability
- TS EN 1022 (seating — determination of stability)
- TS EN 1730 (tables — stability tests)
- TS EN 16121 / 16122 (storage furniture — stability)
- ICH Q1A(R2) (stability testing of new drug substances and products)
- ICH Q1B (photostability)
- ISO 18811 (guidelines on stability testing of cosmetic products)
Stability Conditions
- Furniture
- Vertical and horizontal loads defined in the standard, applied at defined points
- Pharmaceutical — long term
- Long-term storage condition defined in ICH Q1A, chosen according to climatic zone
- Pharmaceutical — accelerated
- Accelerated condition defined in ICH Q1A; typically monitored for six months
- Cosmetics
- Monitoring under room, high-temperature, low-temperature and cyclic conditions
Equipment for Stability
- Stability (tip-over) test platform and loading rigs
- Climate chambers (temperature and humidity controlled)
- Photostability chamber
- HPLC and analytical measurement systems
- pH meter, viscometer and microbiological facilities
Sample Requirements for Stability
- A fully assembled product for furniture; the declared use class must be provided
- Specimen with its market packaging for cosmetics and pharmaceuticals
- A separate specimen is required for each time point to be pulled
- Formulation, packaging material and batch information must be provided
Duration of Stability
The furniture stability test is short. Cosmetic and pharmaceutical stability studies are inherently long: the accelerated condition typically runs six months, and the long-term study runs for the declared shelf life, with specimens pulled at defined time points.
Stability Procedure
- 1For furniture, the product is placed on the defined floor and conditioned.
- 2Vertical and horizontal loads are applied at the points defined in the standard; tipping is observed.
- 3For cosmetics and pharmaceuticals, specimens are placed in chambers at the defined conditions.
- 4Specimens are pulled at the defined time points.
- 5Appearance, pH, viscosity, active substance content, degradation products and microbiological properties are measured.
- 6Results are assessed as a trend over time.
Stability Acceptance Criteria
In furniture, the acceptance criterion is that the product does not tip over under the defined loads. In cosmetics and pharmaceuticals, it is that specification limits are maintained over the shelf life; the limits are defined in the product's own specification, and come from the pharmacopoeia monograph where one exists.
Evaluation of Results
In furniture, each loading point is assessed separately; passing at one point does not cover another. In pharmaceuticals and cosmetics, accelerated results alone do not determine shelf life — they support the long-term data; if a significant change is seen, an intermediate condition study is required.
Stability Report
- Product identification and test scope
- Loads applied, points and tip-over observation for furniture
- Storage conditions and time points for cosmetics and pharmaceuticals
- Measurement results for each time point
- Trend assessment and conclusion
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- (EU) 2023/988 General Product Safety Regulation
- (EC) 1223/2009 Cosmetic Products Regulation
- 2001/83/EC Directive on Medicinal Products for Human Use
Pharmaceutical Analysis — What Does This Testing Field Cover?
The section below describes the field that the Stability test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Pharmaceutical analysis determines the identity, purity, quantity and behaviour of an active substance and of the finished product. What sets this family apart is that the methods are largely defined in PHARMACOPOEIAS: the European Pharmacopoeia (Ph. Eur.) and the United States Pharmacopeia (USP) give both the method and the acceptance framework together.
The binding nature of the pharmacopoeial method shapes how the field works. In other sectors a laboratory can choose a suitable method, whereas here the method in the monograph governs; if an alternative method is to be used, its equivalence must be demonstrated. This is what makes results comparable worldwide.
Analyses are carried out in several groups. Identity and assay (HPLC, UV, titration) show what the product is and how much active substance it contains. The impurity profile and residual solvents look for unwanted compounds arising from the manufacturing process. Elemental impurities address metals originating from catalysts and equipment. Dissolution and disintegration behaviour is the most important in vitro indicator of how the drug will be released in the body.
The DISSOLUTION TEST is one of the most critical measurements in the field. It is not enough for a tablet to contain the right amount of active substance; that substance must dissolve at a suitable rate. The dissolution profile is used to assess the effect of formulation changes on bioavailability and holds a central place in generic drug licensing.
METHOD VALIDATION is a mandatory step in this family. If a pharmacopoeial method is used, it is verified that the method works properly under that laboratory's conditions. If an in-house method has been developed, it is validated against parameters such as linearity, precision, accuracy, specificity, limits of detection and quantification, and robustness. A result produced with an unvalidated method cannot be used in a licence dossier.
Stability studies determine shelf life and are the longest-running work in the field. The product is held under defined temperature and humidity conditions, analysed at set intervals, and the results become the basis of the shelf life and storage condition claims. Accelerated conditions give preliminary information but real-time data is what counts.
The microbiological side is a separate body of work: microbial enumeration, testing for specified microorganisms, sterility testing for sterile products and the bacterial endotoxin test. For sterile products, packaging integrity and sterilisation validation also come into play.
Data integrity has moved to the centre of inspections in recent years. It is not enough for the result to be correct; the raw data must be traceable, unalterable and auditable. Validation of electronic record systems has therefore become an inseparable part of analysis.
Method groups in this field
Identity and assay
HPLC, UPLC, UV-Vis spectrophotometry, titration, identity confirmation by FTIR.
Impurities and residues
Related impurities, degradation products, residual solvents (GC headspace), nitrosamine screening.
Elemental impurities
Determination of elemental impurities by ICP-MS and ICP-OES and the associated risk assessment.
Physicochemical
Dissolution and disintegration, hardness, friability, uniformity of dosage units, water content (Karl Fischer), particle size.
Microbiological
Microbial enumeration, specified microorganisms, sterility, bacterial endotoxin, preservative efficacy.
Stability
Real-time and accelerated stability studies; photostability and in-use stability.
Commonly confused in this field
- The pharmacopoeial method is binding; an alternative method may be used only by demonstrating its equivalence.
- A result produced without method validation cannot be used in a licence dossier.
- Accelerated stability does not replace real-time data; shelf life is supported by real-time results.
- The dissolution profile is sensitive to apparatus type, agitation rate and medium; the conditions must be complete in the report.
- A shortcoming in data integrity produces a non-conformity in an inspection even when the result is correct.
- A change of formulation or supplier requires analytical comparison and, where necessary, a new stability study.
Which decisions these results support
- The licence dossier and batch release
- Determining shelf life and storage conditions
- Method transfer and method validation
- Incoming raw material acceptance control from suppliers
- Assessing the effect of a formulation change on bioequivalence
Related Tests
Frequently Asked Questions About Stability
We anchor the cabinet to the wall — is a stability test still needed?
Yes. Product standards address both anchored and unanchored conditions, since the user may not fit the anchor. Supplying the anchoring hardware with the product and clear instructions is a separate compliance matter.
Does accelerated stability determine shelf life?
Not on its own. Accelerated data gives an early prediction and can support a provisional shelf-life claim, but the final shelf life is supported by long-term study data.
Are stability and challenge testing the same thing in cosmetics?
No. Stability studies track the product's change over time; challenge testing (preservative efficacy) deliberately inoculates the product with micro-organisms to show the preservative system works. Both are required together in the Product Information File.