The chemical characterization of materials is an essential aspect of the regulatory review and approval of medical devices in the European Union (EU) and most major markets worldwide. Chemical characterization is also an essential aspect of the overall biocompatibility assessment process, which helps to ensure that the potential benefits of using a given medical device are not outweighed by the potential biological risks associated with that device or its components or materials.

Chemical Characterization involves the identification of a material and the identification and quantification of its chemical constituents as part of an assessment of the overall biological safety of a medical device. It also involves a measurement of the level of a leachable substance (traces of chemicals originating from raw materials and fabrication processes that may result in exposure to patients) in a medical device in order to:

• Allow the assessment of compliance with the allowable limit derived for that substance from health based risk assessment
• Determine equivalence of a proposed material to another material or to another final device / prototype
• For screening of potential new materials for suitability in a medical device for a proposed clinical application.

According to ISO 10993-18:2005, chemical characterization is the process of obtaining chemical information by data gathering and complementary generation (interaction between two different genes that work together to create a specific phenotype or visible trait that isn’t possible if they are separated), for example, by chemical testing. More precisely, it entails the use of analytical chemistry to identify and qualify the amount of chemicals extracted from a device.

There are two categories of tests to perform a chemical characterization: direct material characterization and evaluation of substances potentially released by the devices.

The first group of tests evaluates the inner chemical properties of materials. The latter assesses those substances that can leach out from a device by conducting an extractable and leachable analysis followed by toxicological risk evaluation based on the tolerable exposure levels. This data should then be evaluated by a group of experts that examine each compound, using existing literature and tools established in ISO 19003-17:2022.

Chemical Characterization is defined by the ISO-10993-18 standards. In order to test the biocompatibility of your medical device, qualitative and quantitative data must be collected on the materials that make up the devices in the context of biological safety. In the absence of such information, the material should be tested using appropriate techniques to collect data on its composition and its potential extractibles.

The ISO 10993-18 standard tests must be performed when developing a new medical device, when changing the manufacturing process or when changing materials and/or suppliers. Please be aware that even if a material has been historically shown to be biocompatible, it must still pass the ISO 10993-18 tests:

Simulated extraction : An extraction with simulated use is performed to estimate the type and quantity of substances expected to be released from a medical device during its clinical use.

Exaggerated Extraction : Extraction intended to result in the release of a larger number or quantity of chemical constituents than would be produced under clinical conditions of use.

Exhaustive Extraction : Multi-stage extraction performed so that the amount of extracted material recovered in a later step is less than 10% of that detected, by gravimetric analysis (or by any other means), in the initial extraction step.
 

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