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E/L Testing Isn’t What It Used to Be

Apr 21, 2021 | Medical Device Testing

Medical device biological safety evaluations have advanced significantly over the last ten years, and regulatory requirements are quickly evolving as well. Turnkey evaluation of testing requirements has progressed into a more device-specific evaluation of risks. It is essential for manufacturers to consider how the changes put in place by ISO 10993-18 will impact their product’s testing needs and any historical compliance of chemical characterization studies.

Complying with the new standard requires a variety of highly sensitive and selective analytical equipment, robust databases and, above all, the expertise to sift through data and identify all chemical constituents. Manufacturers are reevaluating their products to ensure past testing strategies still hold up to current regulatory expectations. To understand how the industry got to this point and forecast where it is headed, we need to start from the beginning.

E/L Gains Momentum

When E/L testing first gained a foothold with medical devices in the early 2000s, methods were focused on qualitative measures. Testing did not generally attempt to quantify the amount of specific chemical constituents present but rather verify major materials present and evaluate total extractable residue.

As certain products were facing public litigation, such as pelvic mesh and breast implants, renewed scrutiny around the risks presented by implantable devices quickly caused the expectations for chemical characterization to be more rigorous, selective and quantitative.

As the decade progressed, even more analytically selective and sensitive techniques emerged, and chemical characterization requirements tightened. Regulators responded with an increased focus on testing device materials and a growing interest in customizing testing to better suit medical devices. In 2016, the US FDA Draft Guidance on ISO 10993-1 reaffirmed the value of chemical characterization when evaluating medical devices.

Recent E/L Testing Trends

Expectations grew along with advanced test methods and equipment that could accommodate increasing regulatory requirements. The 2016 US FDA guidance on the use of ISO 10993-1 required two to three solvents per instrumentand three replicates, thus increasing the investment that companies made during biological safety evaluations.

Around 2017, regulatory agencies began requiring exhaustive extractions (that is, multiple extractions on the same device) for permanent implants. Then in 2018, regulators published a revised version of ISO 10993-1, putting new guidance in place. Specifically, it made chemical characterization and the subsequent risk assessment fundamental components in assessing device safety.

This expectation meant submissions must examine chemistry information and risk assessment to drive their biocompatibility test strategy, and manufacturers must provide justification to support final submissions. Additionally, reviewers examined the training and qualifications of the expert personnel performing these tests. 

Internally, the U.S. FDA showed increasing alignment around chemical characterization and toxicological risk assessments, asking how those play into evaluating a device’s biological safety. By 2019, reviewers began requiring exhaustive extraction on prolonged devices as well as permanent devices, which extended the timeline needed to perform testing and increased associated costs.

E/L Testing Today & Going Forward

The publication of ISO 10993-18:2020 marked a significant milestone for the medical device industry. The 2020 revision continued to push expectations and the subsequent approach forward.

This revision provided increased guidance for tailoring chemical characterization to each device by establishing thresholds based on device size, duration and type of patient contact, and the target patient population. For example, reviewers began expecting confidence intervals for identification and implemented the analytical evaluation threshold (AET) as a common baseline for chemistry studies. The AET is essential to achieving an accurate risk assessment. It also helps avoid regulatory scrutiny by requiring qualified chemists to work alongside toxicologists.

The methodologies that laboratories employ today are evolving rapidly, perhaps even faster than the standards themselves. Thus, the concept of “state-of-the-art” procedures is gaining attention as regulators’ expectations grow in tandem with the industry’s capabilities. This is evident with the September 2020 release of International Standard ISO 10993-1, “Biological evaluation of medical devices – Part 1: Evaluation and testing within a risk management process.” As we near the upcoming publication of ISO 10993-17, toxicological risk assessments are positioned next to advance the practices in place. Still, manufacturers may find these latest regulations challenging to keep up to date with the continuously evolving regulatory landscape.

Keeping Up with Chemistry

If you have not conducted E/L testing in recent years, it may be time to consider retesting to satisfy the evolved science and regulations. For many products, testing conducted prior to the publication of ISO 10993-18:2020 may need reevaluation according to the new guidance.

Given the new role that chemical characterization has taken in testing and the new expectations to identify biological concerns, it is critical to consider E/L testing as an essential ingredient in preparing a successful medical device submission. Looking to dive further into the details? Check out a detailed recap about ISO 10993 in “Planning and Predicting for ISO 10993: Part 18 & Part 17.

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WuXi AppTec provides a broad portfolio of R&D and manufacturing services that enable companies in the pharmaceutical, biotech and medical device industries worldwide to advance discoveries and deliver groundbreaking treatments to patients. As an innovation-driven and customer-focused company, WuXi AppTec helps our partners improve the productivity of advancing healthcare products through cost-effective and efficient, socially responsible and sustainable solutions – and has received ESG (Environment, Social and Governance) A Ratings from Morgan Stanley Capital International since 2019. With industry-leading capabilities such as R&D and manufacturing for small molecule drugs, cell and gene therapies, and testing for medical devices, WuXi AppTec’s open-access platform is enabling more than 4,200 collaborators from over 30 countries to improve the health of those in need – and to realize our vision that “every drug can be made and every disease can be treated.”

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