Usability of a High-Volume Autoinjector (HVAI): Addressing the User Need for Rapid High-Volume Subcutaneous Drug...

The increasing prevalence of biologic therapies requiring high injection volumes has created a need for devices that enable patient self-administration without compromising comfort or adherence. Conventional auto-injectors typically deliver 1-2 mL, necessitating multiple injections for higher doses, which can negatively impact patient experience and compliance. The high-volume auto-injector (HVAI) was developed to address this unmet need by enabling delivery of up to 10 mL in a single injection while maintaining ease of use and minimizing injection burden.A human factors study evaluated HVAI usability across representative user groups, including participants with physical impairments such as reduced hand strength or dexterity, which can make device use challenging. 74 injections were performed with injection times ranging from 21 to 60+ seconds; 69 were successful, five were incomplete. Of the successful injections, 88% met or exceeded a three-second post-injection hold time, the remaining injections with shorter hold times still delivered full doses. All five incomplete injections were classified as wet injections caused by premature device removal before the final indication. Despite the user dexterity impairments, most participants rated the auto-injector as easy to use and reported high confidence in dose delivery, supported by ergonomics and audible/tactile cues. Improvements in completion indicators were suggested.