Leaching content refers to the medical equipment and water or use of the liquid in the role, from the release of chemicals, medical devices, for example: additives, sterilization agent residue, process residues, degradation products, solvents, plasticizer, lubricant, push the agent, stabilizer, antioxidant, coloring, fillings and monomer and other substances.

Leachables can be divided into primary and secondary components. Primary component refers to the substance originally existing in the product material, such as: basic component of the material (polymer matrix, additives, stabilizers, etc.), impurities (trace components in the composition), pollutants, etc. Secondary components are substances that do not originally exist in the product materials, such as those produced in production and processing, and are derivatives of primary components.

Basic processes and requirements:

1. Clear material composition and production process of products

Identify product materials and product material composition, as well as all chemical contaminants to which the product may be exposed during production.

2. Certification materials meet relevant quality control standards

Product materials shall be tested in accordance with appropriate quality control standards and shall be certified to conform to product quality control requirements.

3. Confirm the leachable material

Provide a comprehensive and complete list of substances from which the product may be extracted. (If it is not available, it can be analyzed by chemical testing later)

4. Extraction study

Provide the leachable substances that may be leached from the finished medical device under conditions of actual use by the patient and the cumulative amounts of these substances.

5. Toxicological assessment

After considering the use of medical devices, the toxicological effects of the types and total amount of leacheable substances in medical devices were analyzed.

6. Identification of leachable substances

Polymer materials are mixtures of chemical components, some of which are bonded to the polymer framework or matrix of the material, and some of which are in a free state and can migrate to the surrounding environment.

Chemicals transported from polymer materials include stabilizers, smoothing agents, antioxidants, monosomes, plasticizers and contaminants.

The factors for the identification of leachables should include not only the chemical characterization of raw materials, but also the processing technology, production environment, degradation and degradation products.

The principle is that the processing process, production environment, degradation and other factors of finished products should be considered on the basis of understanding the chemical characterization information of raw materials.

8. Study on extraction of leachable substances

8.1 Selecting a Typical Product

In the extraction study, typical products should be selected for testing. The contact area between materials and clinical infusion liquid in typical products should be typical, and the structure and function should be the most complex model.

8.2 Selection of extraction conditions

The leaching conditions of medical device leachables shall not change the properties of leachables, and the leaching process must be technically capable of proving that the leachables are consistent with those produced by real market products under the worst environmental conditions.

Representative extraction solution, extraction temperature and extraction method should be selected according to the expected use, and extraction conditions should represent the worst conditions of the device in clinical practice.

8.3 Characterization of leachable substances

The process of characterization of leachable substances is qualitative and quantitative. The test method should be sensitive, reliable and repeatable.

9. Toxicological assessment

After the study of leachable extraction from medical devices, the leachable extracted from medical devices should be judged whether the leachable has toxic effect on human body based on the literature study.

The main basis of judgment is to determine the biological risk and tolerable intake of the leachable substance.

Tolerable Intake (Tolerable Intake; TI) is the average daily intake (mg/kg.d) of a substance, calculated on the basis of body mass, which is not considered to be significantly harmful to health over a specified time period.