ISO/TR 37137:2014

Overview - ISO/TR 37137:2014 (Cardiovascular biological evaluation - Guidance for absorbable implants)

ISO/TR 37137:2014 provides interim, part-by-part guidance to adapt biological evaluation methods (the ISO 10993 series) for intentionally absorbable implants used in cardiovascular applications. The Technical Report focuses on managing the effects of intentionally released soluble components and degradation products so that standard biocompatibility and hemocompatibility test results are not erroneous or misleading. Recommendations are provisional; any interim adjustments require a documented written justification and may later be incorporated into the respective ISO 10993 parts.

Key technical topics and requirements

• Interim adjustments to ISO 10993 test methods: Practical options for modifying in vitro test conditions when degradable materials alter assay environments.
• pH and osmolality considerations: Where degradation products change media pH/osmolality, controlled adjustment (buffering or dilution) to physiologic ranges can be acceptable - provided the change is justified and retesting shows resolution. (Example: care with osmolality dilution for magnesium alloys; minimum cited value ~105% of normal for some cases.)
• Degradation products and leachables: Identification, quantification and toxicological assessment of degradation products released during processing, storage or in vivo degradation. Chemical characterization can support substitution of some biological tests with a toxicological risk assessment.
• Particulate matter: Assessment of transient particulates formed during degradation; full biocompatibility testing of particles may be unnecessary when equivalence to well-characterized materials is demonstrated.
• Sterilization impact: Biological evaluation should use the final sterilized device or provide rationale and data showing test articles are representative of the final device. Harsh sterilization can create different by-products and must be considered.
• Drug–device combination products: Test both the finished device with the API and the device without the drug when APIs may affect degradation or biological response; assess potential interactions.

Practical applications - who uses this standard

• Medical device manufacturers developing absorbable cardiovascular implants (stents, sutures, scaffolds)
• Biological safety and regulatory affairs teams preparing ISO 10993 test plans and justifications
• Independent testing laboratories and CROs performing biocompatibility and hemocompatibility testing
• R&D and quality engineers evaluating material selection, sterilization, and combination product designs

Related standards and references

• ISO 10993 series (notably: ISO 10993-1, -3, -4, -5, -6, -7, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18)
• ISO/TS 10993-19, ISO/TS 10993-20
• ISO/TR 15499 (general guidance)
• ISO/TS 12417 (drug–device combination guidance for vascular devices)

Keywords: ISO TR 37137, absorbable implants, biological evaluation, ISO 10993, degradation products, leachables, biocompatibility, hemocompatibility, sterilization considerations, drug-device combination.