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Strategies for More Effective Human Factors Engineering for Injectables

Discover strategies to optimize the human factors engineering process for injectable products.

Human factors engineering (HFE) is a cornerstone in the development and life cycle management of combination products, especially injectables. From early concept to manufacturing, HFE helps minimize use-related hazards and risks and helps ensure patients can safely and effectively use injectable combination products.1,2,3

However, HFE often presents significant challenges. Many companies find themselves caught in cycles of multiple usability tests. For manufacturers of legacy products already on the market, evolving regulatory guidance and requirements such as those required for domestic (FDA) and international product development (IEC, ISO, etc.) may lead to the need for additional testing. Human factors results, rarely perfect to begin with, can be even more challenging for legacy products due to existing design and manufacturing constraints.

These challenges highlight the need for a more efficient approach to human factors engineering, particularly for legacy products. One powerful tool for optimizing human factors engineering is the Use-Related Risk Analysis (URRA), especially when implemented early in the product development process. By identifying potential use-related hazards from the outset, URRA can significantly reduce the number of human factors evaluations needed. This approach, combined with other best practices, can help ensure the best possible outcomes for patients while efficiently navigating the complex landscape of regulatory requirements and manufacturing constraints for injectable products.

The role of HFE in injectable| product development

Prior to the creation of a URRA, a User Task Analysis (UTA) should be established. An essential tool in the HFE process, the UTA provides a systematic breakdown of all the steps a user must perform to use the product correctly. This analysis helps identify potential use errors, areas of user confusion, and opportunities for design improvements. To create a UTA, human factors engineers observe and interview potential users, review similar products, and consider various use scenarios.

From the UTA, critical tasks are identified. These are tasks that, if performed incorrectly or not at all, could result in harm to the patient or compromise medical care.4 Examples of critical tasks for an injectable product might include proper dose selection, correct injection site identification, or maintaining the required hold time after injection.

Defining critical tasks is crucial as they become the focus of subsequent human factors studies and risk mitigation efforts. They inform the design of instructions for use, training materials, and the product itself. By concentrating on these key areas, manufacturers can allocate resources more effectively and design targeted solutions to enhance product safety and usability.

Early URRA implementation

URRA is a comprehensive approach to identifying and mitigating potential use-related hazards associated with a product. Compared to Use Failure Mode Effects Analysis (uFMEA), which focuses primarily on device failures, URRA takes a broader view, considering how users interact with the product in more varied environments and scenarios.

The URRA process involves systematically evaluating each step of product use, from preparation to disposal, to identify potential use errors and their consequences. This allows for a more nuanced understanding of risk, considering factors such as user characteristics, use environments, and potential misuse scenarios.

Implementing URRA early in the product development process offers significant benefits. By identifying potential risks early, manufacturers can make informed design decisions that inherently reduce these risks. This can lead to fewer design iterations and potentially fewer human factors studies, as major use-related risks are addressed before formal testing begins.

The cost and time savings resulting from early URRA implementation can be substantial. By reducing the need for late-stage design changes and minimizing the number of iterative human factors studies, companies can optimize their development process and potentially bring products to market faster.

Best practices for improving human factors engineering

Several best practices can enhance HFE effectiveness, focusing on early risk identification, study design, and leveraging expert knowledge to create safer, more user-friendly products.

The life cycle approach to HFE ensures that safety considerations are not just a one-time effort but are continually reassessed and refined based on real-world use data and evolving user needs. This integrates HFE throughout the entire life span of injectable products, from initial concept to post market surveillance.

During concept and feasibility studies, HFE principles guide initial design considerations, ensuring that user requirements are integrated from the outset. As a product moves through development stages, human factors evaluations become more detailed and specific, informing design iterations.

A key focus of HFE throughout the product life cycle is risk mitigation. By identifying potential use errors and their consequences early in the development process, manufacturers can implement design changes or other risk control measures to enhance product safety. This proactive approach not only improves the end product but can also streamline the regulatory approval process.

Designing effective human factors studies

Well-designed human factors studies are crucial for validating design decisions and ensuring product safety. A strong study design begins with clear objectives and a comprehensive understanding of the product’s intended users and use environments.

One key aspect of effective study design is preparing for unexpected results. While it is important to have hypotheses about how users will interact with the product, it is equally essential to be open to surprising findings. These unexpected results often provide valuable insights into user behavior and can lead to significant improvements in product design.

The outcomes of human factors studies should directly inform risk mitigation strategies, in line with the URRA. For instance, if a study reveals that users consistently struggle with a particular aspect of the product that was identified as critical during the URRA process, this information should feed back into design, leading to changes in the product itself, its labeling, or associated training materials as necessary.

Leveraging subject matter expertise

The complexity of human factors engineering in injectable product development necessitates the involvement of experienced professionals. Subject matter experts bring a depth of knowledge that can be invaluable in navigating regulatory requirements, designing effective studies, and interpreting results.

These experts can draw on their experience with similar products or use environments to anticipate potential issues and suggest effective solutions. They can also provide context for study results, helping to differentiate between critical issues that require immediate attention and those that may be less impactful.

However, it’s also important to balance this expertise with fresh perspectives. New team members or consultants may spot issues that those more familiar with the product might overlook. This balance of experienced insight and new viewpoints can lead to more comprehensive and innovative solutions to human factors challenges.

Regulatory considerations and recent guidance

While implementing these strategies, companies must consider regulatory compliance. The FDA’s release of draft guidance on URRA implementation marks a significant development in the regulatory landscape and underscores the importance of URRA in the product development process.5

For companies developing injectable products, this guidance has several important implications:
  • Systematic risk identification: The step-by-step process outlined in the guidance seeks to ensure a comprehensive approach to identifying potential use errors and their associated harms
  • Focus on critical tasks: The guidance’s emphasis on categorizing tasks as critical or non-critical reinforces the importance of identifying and focusing on those tasks that could lead to harm if performed incorrectly
  • Prioritizing inherently safe design: The guidance’s hierarchy of risk controls encourages companies to address use-related risks through product design wherever possible
  • Ongoing risk management: Companies should update the URRA throughout the product life cycle

Lessons from autoinjector human factors studies

The implementation of optimized HFE strategies can be best understood through practical examples. Autoinjector human factors studies provide valuable insights into how these approaches work in real-world scenarios, demonstrating both challenges and opportunities in the HFE process.

When evaluating autoinjector design, it has been seen that a systematic approach to HFE can identify critical use issues, inform design decisions, and ultimately lead to safer, more effective products. When performing HFE studies, a company can not only highlight areas where design improvements or additional user training may be necessary but also demonstrate how data-driven risk mitigation strategies can be developed and justified.

For example, when conducting a recent HFE study, it was found that while most users could successfully remove the safety release and administer the injection at the correct site, participants were challenged with following the instructions for use, specifically as to hold time (see Figure 1). However, when patients were trained on how to appropriate use the device, the demonstrated successful task completion and administered the correct number of doses based on symptom severity (see Figure 2).

An analysis of the hold time data showed that while only 31.9% of injections were held for the full 10 seconds or more. However, when patients were appropriate trained on how to use the device all trained participants demonstrated successful task completion and administered the correct number of doses based on symptom severity (see Figure 2). In contrast, as shown in Figure 3, only 205 of untrained participants were able to do so.

These findings underscore the critical role of effective training materials and patient education for such devices.

Using this data to justify risk mitigation strategies involved a careful balance between ideal scenarios and real-world use. While the goal remains to have users follow instructions precisely, human factors studies such as these examples provide valuable information about how the product performs under less-than-ideal conditions.

However, it’s crucial to note that such data should not be used to justify poor design or unclear instructions. Instead, it should inform iterative improvements to the product, its labeling, and associated training materials. The goal is always to make the product as intuitive and error resistant as possible while also ensuring it can perform effectively under a range of real-world conditions.

Although the studies originally traced critical tasks through the uFMEA, a URRA was created after evaluation of results and allowed for clear definition of use cases, tasks, subtasks, and potential errors. This allowed for exploration of design opportunities that were not previously considered across the user interface, including packaging, outer cartons, and instructions for use, thus demonstrating the value of applying URRA.

A call for proactive human factors engineering

As the landscape of injectable drug delivery continues to evolve, the importance of proactive and efficient HFE cannot be overstated. The strategies and best practices discussed in this article represent a shift toward a more effective approach to HFE that can significantly impact product development processes.

By implementing tools like the URRA early in the development cycle, companies can anticipate and address potential use errors before they become costly design flaws. This proactive approach not only enhances product safety but can also lead to more efficient development timelines and smoother regulatory pathways.

However, the field of HFE is dynamic. As new technologies emerge and user needs change, HFE processes must adapt. Preparing for future challenges requires a commitment to ongoing learning and flexibility in approach. Companies should stay abreast of evolving regulatory guidance, emerging technologies, and changing user demographics to ensure HFE processes remain effective.

Partnering with experienced HFE professionals can aid companies in effectively implementing these strategies. These experts can provide valuable insights, guide companies through complex regulatory requirements, and help interpret study results in ways that lead to meaningful product improvements. 

References
  1. Kumoluyi, R., and Khanolkar, A. Risk Management in Drug-Device Combination Product Development. Ther Innov Regul Sci. 2022 Sep;56(5):685-688. doi: 10.1007/s43441-022-00425-w. Epub 2022 Jun 26. PMID: 35753035; PMCID: PMC9356918.
  2. Reason, J. Human error: models and management. BMJ. 2000;320(7237):768–70.
  3. Association for the Advancement of Medical Instrumentation. Risk management guidance for combination products. AAMI TIR105:2020.
  4. FDA Guidance. Applying Human Factors and Usability Engineering to Medical Devices, 2016.
  5. FDA Guidance. Purpose and Content of Use Related Risk Analyses for Drugs, Biological Products, and Combination Products, 2024.

Amy Lukau is the Senior Human Factors Lead at Kindeva Drug Delivery and assists in the development of advanced proprietary autoinjector technology for commercial and government sectors. She leverages over fourteen years of experience in biotechnology and pharmaceutical research in human factors engineering and other areas. 

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