ISO/TS 37137-1 Biological Evaluation of Absorbable Medical Devices - Part 1: General Requirements

The standard “ISO/TS 37137-1 Biological evaluation of absorbable medical devices - Part 1: General requirements” published by the International Organization for Standardization (ISO) describes the requirements for evaluating absorbable medical devices during a biological risk assessment based on the standard “ISO 10993-1 Biological evaluation of medical devices - Part 1: Evaluation and testing within the risk management process”.

For the purposes of this standard, the following terms and definitions apply:

• Absorption is the effect of a non-endogenous (foreign) material or substance, or its decomposition products, passing through or being assimilated by cells or tissues, or both, over time.
• A degradation product is an intermediate or final substance resulting from the physical, metabolic or chemical decomposition of a material or agent.
• Degradation is the physical, metabolic or chemical decomposition of a material or substance.
• A leachate is a substance that can be released from a medical device or material during clinical use or simulated clinical use. For absorbable medical devices, leachates can be substances released from the product during manufacturing or substances formed and released as a result of its degradation (i.e., degradation products).
• The final product is a medical device or medical device component that has undergone all manufacturing processes for the medical device to be marketed, including packaging and sterilization, if applicable. The final medical device or sterilized finished medical device has the same meaning as the final product in this standard.

Biological assessment is the evaluation of a medical device, medical device component, or a material to determine the likelihood that the medical device material, the medical device design, or both, will cause an unacceptable adverse systemic and local effect on surrounding cells and tissues.

The biological assessment of an absorbable material should be carried out in accordance with ISO 10993. Any changes to the methods specified in the ISO 10993 series of standards should be justified in a written biological risk assessment.

Degradation products may be released into the removal medium or tissue, or both, or may persist in the degrading implant. Released degradation products occurring prior to or during product use should be characterized.

Differences in processing can affect the biocompatibility of the final product. Simply showing the same composition is not sufficient, as many other factors (e.g. degree of purity, grain size and crystal structure for metals, molecular weight, sterilization mode) can affect resorbable material performance and biocompatibility. A completed device biorisk assessment using information from chemical analyses of resorbable materials and their degradation products, combined with toxicity data from literature, can support some of the biological endpoints described in ISO 10993-1.

Additionally, biocompatibility testing is not designed to evaluate biological responses to absorbable devices throughout degradation. Since absorbable devices are constantly changing in the physiological environment and may exhibit different adverse biological responses at different stages of degradation, testing at different stages of device degradation may be necessary to demonstrate safety.

The final product evaluation shall be performed on sterilized finished medical devices or test samples that are representative of the final medical device. If the final product is not used for testing, a justification shall be provided that includes:

• Explanation of all differences between the test substance and the final product
• Data showing that any differences between the test substance and the final product do not affect its chemistry or degradation kinetics

Sterilization methods and conditions should be carefully evaluated and justified before biological testing. For irradiation sterilization, caution should be exercised when medical devices are sterilized using higher radiation doses. With an increased dose, significant amounts of different chemical degradation products may be produced or non-toxic chemicals may be degraded into toxic species. For other sterilization methods, toxicity may increase with increasing exposure time.

For medical devices containing an active substance (API), the presence of a pharmaceutical substance may affect the response in the biocompatibility test. Therefore, testing the medical device separately with and without the API should be considered, but may not be necessary. In addition, available information on the API alone and possible interactions between the pharmaceutical ingredients and the as-manufactured absorbable materials or degradation products should be evaluated for their impact on medical device biocompatibility and degradation.

Our organization has a strong staff that closely follows the developments in science and technology in the world and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also testing services in accordance with the “ISO/TS 37137-1 Biological evaluation of absorbable medical devices - Part 1: General requirements” standard.