Defining User Needs for Drug Delivery Medical Devices: A Practical Example
In a previous post, we discussed the importance of understanding and defining user needs to guide the development of effective medical devices and drug delivery devices. Today, I’ll illustrate this process with a specific example: the development of a prefilled syringe. Prefilled syringes are widely used in the pharmaceutical industry, and their design must consider the unique needs of various users to ensure the device is safe, effective, and easy to use. These principles are not only applicable to syringes but extend to a wide range of medical devices.
Designing a prefilled syringe or any medical device that addresses user needs requires a clear understanding of how users interact with the device, the challenges they face, and how the design can accommodate these challenges. Below, I will outline a set of common user needs relevant to prefilled syringes and drug delivery medical devices, demonstrate how these needs inform the design process, and explore how they can be validated through Human Factors (HF) evaluations.
User Needs: Prefilled Syringe and Drug Delivery Medical Device Example
The following list highlights several user needs frequently encountered during the development of prefilled syringes and similar medical devices. These needs should be tailored to the specific characteristics and usage scenarios of your intended users.
| User Need | How this informs your design? | How it can be validated? |
|---|---|---|
| The user must be able to identify the device in the intended storage. | The label and carton must be designed to ensure it is clearly differentiable among potential comparators by users with expected visual deficiencies (e.g., colorblind users). | Include a medical device and/or packaging retrieval task in your HF evaluations. Place potential comparators in the storage and see if participants can correctly identify the product. |
| The user must be able to understand how to use the medical device. | The instructions for use must be written in lay language and include self-explanatory graphic descriptions, ensuring that users with low health-literacy skills (e.g., kids or users without secondary education) can operate the device safely. | Include a knowledge-based assessment in your HF evaluations. Ensure that users with low health-literacy skills can identify, understand, and follow the instructions to safely use the medical device. |
| The user must be able to remove the cap in the intended use environment. | The cap removal force must not exceed a determined value (e.g., 10 Newtons), which should be what your most vulnerable users (e.g., 10-year-olds or elderly users with motor impairments) can exert in expected use environments. | Test devices with caps set to the highest removal force that will be available in the market. Include vulnerable populations in your evaluations to confirm they can remove the tightest cap. |
| The user must be able to activate the device in the intended use environment. | The activation force required to operate the device must not exceed what your most vulnerable users (e.g., 10-year-olds or elderly users with motor impairments) can exert. | Simulate conditions where the activation force is the highest expected, artificially setting the medical devices that way, and ensure that the most vulnerable users can still activate the device. |
| The user must be able to safely dispose of the device. | The device must fit into a standard sharps container if users are expected to dispose of it there. | Provide a sharps container during user evaluations and check if participants can easily dispose of the medical device after use. |
Translating User Needs into Design Requirements
Defining user needs at a granular level ensures that your design addresses the specific challenges faced by diverse user groups. These needs directly influence design inputs and decisions, such as cap removal force or instructional clarity. The structured documentation of user needs also forms a foundation for evaluating usability and compliance with IEC 62366 standards.
For example, specifying that "the user must remove the cap in the intended use environment" necessitates a detailed examination of removal force and ergonomics. Similarly, specifying that "the user must deliver the treatment effectively" leads to decisions about injection force and timing to accommodate the physical capabilities of all user groups.
Creating a visual matrix linking user needs to design inputs and validation tasks is a practical approach. This method not only simplifies regulatory submissions but also ensures alignment between defined inputs and user validation processes.
Validation Through Human Factors Evaluations
After defining user needs, validating them through Human Factors evaluations is essential. HF evaluations simulate real-use conditions, helping ensure the device meets safety, usability, and effectiveness standards across user demographics.
In the case of a prefilled syringe or similar medical device, these evaluations might involve tasks like identifying the syringe among similar products, following instructions, or testing cap removal and injection forces. Each test confirms that the device fulfills its intended user needs. For a comprehensive guide to conducting these validations, refer to our post on "Effective Summative Evaluations".
Expanding to Medical Device Applications
While this example focuses on prefilled syringes, the principles outlined here are broadly applicable to a range of medical devices. Whether you’re designing auto-injectors, inhalers, or wearable devices, understanding user needs and translating them into actionable design requirements is crucial for creating effective solutions. Regulatory bodies like the FDA and EMA emphasize the importance of usability testing and human factors evaluations for medical devices to ensure safety and efficacy.
Conclusion
Defining and validating user needs is foundational to developing user-centered medical devices and drug delivery solutions. In the example of a prefilled syringe, understanding and addressing the challenges faced by patients, caregivers, and healthcare professionals ensures safer, more effective, and easier-to-use devices. By following a structured approach, developers can align their designs with real-world user expectations, bridging the gap between regulatory compliance and practical usability.
