Design and labeling differences between generic and reference listed drug inhalers: human factors considerations in...

While generic inhalers are approved based on therapeutic equivalence to their reference listed drug (RLD) counterparts, design and labeling differences may unintentionally affect product usability and patient adherence. Comparative use data for drug-device combination products such as inhalers is limited, leaving gaps in understanding how design variations influence use errors.

This study systematically compared five RLD inhalers and eight US FDA-approved generic counterparts selected from the US FDA Orange Book. The data was analyzed using a structured framework to classify and compare physical characteristics, labeling elements, and instructional cues.

Differences were identified across all five groups, including variations in device shape, mouthpiece design, dose counter placement, handling technique, and instruction. Group 1 showed the most differences. These differences may result in errors such as incorrect device handling, reduced drug deposition, or increased difficulty learning proper inhaler techniques.

Findings revealed that design and labeling differences can introduce cognitive and physical product use challenges, potentially impacting proper inhaler use and patient adherence. While this study relied solely on publicly available materials, future work should incorporate user testing, digital human modeling, and assessments across patient populations with varying use characteristics.