If you’re working on a generic inhaler or any orally inhaled product for asthma or COPD, you’ve probably come across the EMA guideline on demonstrating therapeutic equivalence (July 2025). But what does it mean for usability? And how does it relate to standards like BS EN 62366-1?
Let’s break it down.
What does the EMA say about usability?
The EMA’s guideline (CPMP/EWP/4151/00 Rev. 2 https://www.ema.europa.eu/en/requirements-demonstrating-therapeutic-equivalence-between-orally-inhaled-products-oip-asthma-chronic-obstructive-pulmonary-disease-copd-scientific-guideline) focuses heavily on pharmacokinetics and in vitro testing to show that a generic inhaler performs similarly to a reference product. But tucked into Section 9 is a key point: if your product is an “integral” drug-device combination (i.e. not reusable), you may need to run a formal usability study.
Why? Because even if your formulation is spot-on, if users can’t operate the device correctly, it could impact safety and efficacy. That’s where usability engineering comes in.
Do I need to do a usability study?
If your inhaler is new or significantly different from the reference product, and especially if it’s intended for children, older adults, or caregivers, then yes, you’ll likely need to run a usability study. The EMA expects you to show that intended users can unpack, actuate, and store the device safely and effectively.
This aligns closely with BS EN 62366-1, which outlines how to apply usability engineering to medical devices. The standard encourages early identification of use-related risks and testing with representative users.
What kind of usability study is expected?
The EMA calls for a summative usability study (also known as a human factors validation test). This involves recruiting participants from each intended user group, typically 15 per group, and observing them as they simulate using the device. You’re looking for use errors, misunderstandings, or anything that could compromise safety or effectiveness.
The study should include realistic tasks like unpacking the inhaler, delivering the first dose, and storing it. For pressurised metered dose inhalers (pMDIs), you might even use placebo devices to assess actuation force.
How does this link to BS EN 62366-1?
BS EN 62366-1 provides the framework for everything the EMA is asking for. It guides you through defining user profiles, conducting task analyses, identifying use-related risks, and validating your design through testing. It also helps you document everything in a usability engineering file which is essential for regulatory submission.
In short, if you follow BS EN 62366-1, you’re already doing what the EMA expects.
What should go in your design history file?
The EMA expects a usability report that includes:
- Intended use, users, and environments
- Study protocol and results
- Risks identified and mitigations implemented
- Evidence that users can operate the device safely
This complements the usability engineering documentation required by BS EN 62366-1, including your use specification, task analysis, use-related risk analysis, and human factors summary report.
Final thoughts
Usability isn’t just a nice-to-have, it’s a regulatory requirement when it comes to inhaled medicines. By applying human factors principles early and aligning with BS EN 62366-1, you’ll not only meet EMA expectations but also design a safer, more user-friendly product.