1. Scope

1. Scope
1.1 This guide is intended to assist primarily in the recognition of potential risks considered unique, less obvious, or particularly important or significant to hydrolysable absorbable polymeric materials, devices, or device components intended for implantation in the human body with optional provision of some additional analysis, estimation, evaluation of those risks included, where appropriate.
1.2 This guide has been generated with principal emphasis on the evaluation of devices formed from synthetic polymers that degrade in vivo primarily through hydrolysis (for example, a-hydroxy-polyesters that undergo bulk degradation). Evaluation methods suggested herein for these polylactone-based polyesters may or may not be applicable to implants formed from materials that, upon implantation, are substantially degraded through other mechanisms (for example, enzymatically induced bio-erosive or oxidative degradation). For absorbable polymers that do not degrade through bulk hydrolysis, users of this document need to independently conduct their own additional research/investigation of the potential risks that accompany enzymatic, oxidative, or other primarily surface-interactive degradation mechanisms.
1.2.1.1 The most common hydrolytically degradable polymeric medical devices are based on a-hydroxy-polyesters, including polylactide, polyglycolide, poly(lactide-co-glycolide), and polydioxanone, for example.
1.2.1.2 Other examples of hydrolytically-degradable polymers include polycaprolactone, poly(diol citrate)
1.2.1.3 Other classes of polymers that may be hydrolytically degradable include polyanhydrides, polyorthoesters, polyurethanes, and polyesteramides, for example.
1.3 This guide is not limited in applicability to the most common absorbable polymers, but rather to inform the user of common risks associated with the use of any hydrolytically degradable polymer as part of a medical device.
1.4 This guide applies to both completely absorbable implants and absorbable implant components of an otherwise non-absorbable device
1.5 This guide is not intended to be considered all inclusive, since some absorbable unique aspects may have not yet been known, identified, or may be dependent upon or made more pronounced by a specific device design.
1.5.1 These polymeric material-oriented guidelines do not necessarily reflect the total needs for any particular implant application (for example, orthopedic, cardiovascular, sutures, and dermal fillers), which likely require additional and potentially essential application-specific requirements and evaluations.
1.6 The risks described in this guide may also be applicable to absorbable ceramics or absorbable metals, but evaluation methods specific for these types of materials will not be covered.
1.7 This guide is intended to cover all forms of absorbable polymeric components and devices, including solid (for example, injection-molded) and porous (for example, fibrous) forms. This guide is also intended to cover devices fabricated from amorphous, semi-crystalline, cross-linked, and all other absorbable polymer systems.
1.8 Adherence to all aspects of these guidelines is not mandatory, in that the described considerations, assessments, and tests listed within this guide are not necessarily relevant for all absorbable implant systems and applications.
1.9 Risks associated with combination of absorbable polymers with bioactive agents (drug delivery) - Absorbable polymers used as a matrix to control the in vivo release of bioactive agents (drugs, antimicrobials, and so forth) may be evaluated according to many of the methods described herein. However, additional test methods not covered by this guide will likely be needed to evaluate a bioactive agent’s composition, loading, release kinetics, safety, and efficacy.
1.10 Composites of absorbable polymers with ceramics and/or metals may be evaluated according to many of the methods described herein. However, additional test methods not covered by this guide will likely be needed to evaluate the composite’s other component(s).
1.11 Risk considerations regarding the cost benefit of a device are outside the scope of this guide.

Keywords

risk assessment; risk identification; implant; hydrolysis; hydrolyzable; hydrolysable; absorbable; bioabsorbable; resorbable; bioresorbable; biodegradable

Rationale

Numerous standards exist for implantable absorbable polymeric materials and general absorbable device guidance can be found in ASTM F2902. However, little guidance exists that underscores the risks involved in the numerous steps needed to successfully bring a reliable implantable absorbable implant device to market, which range from raw material quality to clinical implant design and post-market surveillance. This standard, which will cite existing standards whenever possible, is intended to uniquely provide a general overview of the steps to market and any related non-obvious or critical risks that may be unique to implants composed of absorbable materials.

The title and scope are in draft form and are under development within this ASTM Committee.