Ian Matthews, design engineering team manager at Owen Mumford, works on the detailed design development of injection products, ensuring all design inputs are achieved to a high quality standard. Here he discusses the crucial role of biocompatibility
The medtech industry is constantly evolving, whether through the need to meet the demands of a growing population, adapt to changing end-user requirements or the implementation of ever improving technologies. A continued awareness and eye for innovation are imperative in the sector, as this can have immediate, positive impact on end-user outcomes.
One such area to consider is the level of awareness and understanding of biocompatibility – the interaction of a living system or tissue with a device – which is a core and fundamental element that must feed into the design, development and manufacture of a medical device. A common definition is ‘the quality of being compatible with living tissue or a living system by not being toxic or injurious and not causing immunological rejection’. In a regulatory sense, biocompatibility is the evaluation required to determine the potential toxicity resulting from bodily contact with a material or medical device.
Human factors are considered throughout product development of medical devices, as usability and patient safety are paramount. Any device that contacts the end-user is engineered to compliment the condition being treated, ensuring minimal risk of harm or discomfort. A biocompatibility assessment must occur whenever a human factors evaluation is required as the device and materials used must be safe and comply with industry regulations. This assessment concentrates on any material within a device that may contact or penetrate the end-user at any time.
A number of elements can influence the biological response of a material, therefore it’s essential these are factored into the planning of and execution of the device development. There are different biological requirements depending on the frequency, duration and nature of human contact. Should the device penetrate the skin to deliver medication, comprehensive testing and toxicological evaluation is required to ensure the materials used do not cause an adverse systemic reaction.
Human factors assessment and refinement is constant throughout the design process. When user interaction is needed to assess the design, the materials and method used must be safe and representative to provide informative results. For clinical trials, all materials that contact users must be proven to be biocompatible before the trial begins. At this stage, it is of paramount importance that the clinical device is safe to use and adheres to regulatory requirements ahead of clinical trials. If not planned effectively, this adds additional time and risk to the project as a full biocompatibility evaluation can require a number of months, especially for materials which breach the skin surface or for implantable products.
Further to human factors considerations, there are additional challenges that can arise within biocompatibility. As well as being biocompatible, materials may also require specific performance characteristics to fulfil their requirements. Often, functional and material safety requirements conflict, and the chosen material is unable to do both. Material requirements must be considered at an early stage of medical device development. Any later and a re-design may be required to achieve product inputs. The earlier in the design process that biocompatibility is evaluated, the better – as identifying potential risks can help streamline the overall medical device development process.
Testing is an important consideration when proving that medical devices will meet regulatory requirements and not cause patients harm; however, biocompatibility testing can be complex and challenging, and if not executed correctly, can have serious commercial consequences. Selecting inappropriate evaluation endpoints and/or choosing to assess an endpoint using an incorrect method (testing or toxicology assessment) can lead to insufficient analysis resulting in regulatory requirements not being addressed, plus a safety risk for the user. This can result in causing significant delay to a successful regulatory submission and product launch. The international standard for device evaluation, ISO 109931, provides guidance on how medical devices can be evaluated within a risk management process. A manufacturer’s knowledge of the testing and assessment processes is extremely valuable to ensure that new devices are developed to meet biocompatibility needs to an efficient timeline.
The team in place to review biocompatibility requirements and define a strategy is key. Previous experience of working with materials is valuable in the design and development phase. Experienced engineering and regulatory teams can support with identifying biocompatibility requirements, providing a wealth of awareness as to what materials or manufacturing techniques can and cannot be used. By utilising this industry knowledge, challenges are highlighted early in the design process, streamlining development and product regulatory submission. Without this material awareness, an unacceptable combination of materials can be used within the device, or irritants could be added as part of the manufacturing process. To enhance awareness and understanding, the wider team’s experience and learnings from other projects must be recorded and shared, to gain efficiencies for new projects and processes.
In addition collaboration with toxicologists is critical to ensure confidence during medical device development. With novel materials, toxicologists can explore the chemical characterisation of each component to determine if any risk exists, which can then quickly inform the design phase of the project. If a change to the manufacturing process is essential to the success of the new device, then additional testing and toxicology evaluations must be incorporated into the product development timeline.
Equally, manufacturers must ensure production devices are representative of the materials and processes evaluated for biocompatibility during the project development phase. A bridging piece is important to demonstrate that the entire production process and environment do not impact the device’s biological response, and therefore produces a safe product for the market.
Another challenge to consider is the requirement to deliver against customer requests as part of the overall device design. Maintaining the ability to optimise product capabilities, whilst considering material restrictions can be a balancing act. If a customer has specified a particular design input, this may determine specific materials to use. If these materials do not fulfill the required biocompatibility endpoints, further research is required.
Regulatory requirements can also provide an additional challenge. The FDA, for example, will share ‘guidance documentation’ which provides comprehensive detail of current regulatory thinking. These documents are extremely useful for regulatory efficiencies but are open to interpretation.
Forecasting challenges and having the right team in place can ensure biocompatibility requirements are considered during an early phase of development. A comprehensive level of understanding internally can prove to be extremely valuable over time.
Ensuring constant awareness of industry regulations and guidance is essential. In order to meet biocompatibility challenges head on it’s important to continue to keep abreast of market regulations and biocompatibility requirements. This means products can be created with a reduced level of risk, which comply with regulatory requirements, without delay in the product timeline. If we don’t encourage continued awareness and innovation, we are at risk of being unable to sustain the highest quality of patient care.
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