Material Equivalence: how to avoid repeating biocompatibility testing ?
A change in supplier, material, or even manufacturing process can call previously completed biocompatibility testing into question. However, when material equivalence can be robustly demonstrated, manufacturers can often continue relying on existing data and avoid costly additional testing.
At Toxi Plan, we help manufacturers navigate these changes by demonstrating material equivalence and maintaining compliance, while minimizing unnecessary repeat testing.
Requirements for cosmetic products manufactured outside the European union
The biocompatibility of a medical device relies in particular on the chemical characterization of the materials, a key step defined by ISO 10993-18. This data serves as the basis for identifying and assessing potential hazards to patients.
In practice, the materials and specifications used may change during development for technical or economic reasons. These changes then raise a crucial question:
"How can we guarantee that tests already carried out remain valid?" In what context is material equivalence relevant?
The chemical characterization of materials, as defined by ISO 10993-18, is a key step in the biological evaluation of a medical device. It begins by identifying the physical and chemical properties of the device’s materials and then, in most cases, by analyzing extractable and leachable substances in the laboratory.
The data obtained serve as the basis for hazard identification and for defining the biological tests to be performed. It is therefore essential that this characterization be carried out on materials representative of those actually placed on the market and in contact with patients.
If materials or processes are modified, it is necessary to verify that the initial evaluation remains valid despite these changes.
Changes in materials and industrial constraints: a reality on the ground
In practice, manufacturers face economic and technical conditions that sometimes lead to changes in product specifications for various reasons:
- Material shortages: these force the manufacturer to turn to an alternative supplier, which appears to be identical to the base material.
- Selection of a higher-performing material: the manufacturer finds a material supplier with more attractive properties, quality, or price.
- Changes in manufacturing additives, cleaning products, or any other ancillary products.
Why is it necessary to establish a material equivalence?
Material equivalence serves to justify certain questions.
As a manufacturer, these questions often arise:
• “Despite this change in material, can we still consider the device non-irritating to the skin?”
• “Despite this change in manufacturing additive, does the cleaning process validation still apply to the device?”
If equivalence can be established (e.g., there is sufficient data and evidence to support equivalence), the process eliminates the need to repeat the tests in question.
This can therefore save time and money.
How does the toxicologist determine your material equivalency?
Demonstrating that the material composition is the same is not sufficient to provide conclusive justification. A toxicologist must conduct a more thorough analysis to minimize non-conformities during audits.
For example, if a material is replaced with another that appears identical in composition, the toxicologist will perform an analysis to ensure that the second material is equivalent in terms of impurities and other traces of unintentionally added compounds.
Indeed, supplier A (original material) and supplier B (replacement material) do not necessarily use the same manufacturing process, which can lead to differences in the compounds that will potentially come into contact with patients. Similarly, if a manufacturing adjuvant is changed, the objective will be to demonstrate that the new adjuvant will not introduce new potentially toxic molecules.
Equivalence must therefore be demonstrated for each test that is to be retained.
Where can I find the relevant data?
The manufacturer's technical documentation
Raw material manufacturers often have access to a wealth of data, such as biocompatibility tests or chemical characterizations. This information is invaluable because it strengthens the demonstration of equivalence between materials.
For example : if a skin irritation test was performed on a replacement material and the device was already deemed non-irritating with the previous material, it is reasonable to assume that this change will not affect this safety criterion.
Scientific literature
Over the years, a wealth of toxicological data has been generated and is now available in the databases of institutions from various sectors (pharmaceutical, food, cosmetics, etc.).
This information can be used to support the demonstration of a material’s equivalence. For example, when a new adjuvant is introduced into a manufacturing process, reliable experimental data can confirm that it is not irritating to the skin and will not affect previously obtained skin irritation results.
What information needs to be collected?
To establish the equivalence of a material, several key pieces of information must be gathered. It is essential to know:
- The precise composition (substances, percentages, chemical identifiers),
- Potential impurities and contaminants (which can influence toxicity).
- The toxicological profiles of each substance must also be considered, covering local, systemic, and long-term effects.
These elements allow for the comparison of materials and the reliable assessment of their equivalence.
What to do when the data is not available?
However, it sometimes happens that this data cannot be collected for various reasons: the supplier does not have it or does not want to provide it, the composition is not well defined, no data is available in the literature, etc.
In this case, before restarting all the tests, it may be worthwhile to conduct a new extractables/leachables study following the same protocol as before. The results of the two extractables studies should then be compared, and an attempt should be made to demonstrate that this change in material or process has not affected the chemical characterization of the device.
In biocompatibility, a change in material or manufacturing process does not automatically mean that testing must be repeated. A robust demonstration of material equivalence, supported by relevant technical and toxicological data, often allows manufacturers to preserve existing results, secure their regulatory documentation, and reduce both costs and time to market.
At Toxi Plan, we support medical device manufacturers in demonstrating material equivalence, helping them manage technical changes while avoiding unnecessary retesting and regulatory delays.
Disclaimer:
The information provided in this article is for informational and educational purposes only. It does not constitute legal advice nor a personalized regulatory consultation. Despite the care taken in drafting this article and verifying its sources, regulations evolve regularly and may be subject to differing interpretations depending on the specific context of each company, product, or market.
Toxi Plan®, its directors, and its employees shall not be held liable for any use made of the information contained in this article without further analysis tailored to a specific situation. Any regulatory or strategic decision should be based on a specific assessment carried out by a qualified professional, with due regard to the applicable regulations, including any provisions or regulatory practices entering into force after the date of publication.