Large Volume Autoinjector Design – Forgotten Considerations: Reflections Of An Executive Advisor

Paul E Jansen, PE, Executive Advisor, Kymanox Corporation

The pharmaceutical industry is increasingly focused on developing high-concentration injectable drug formulations, leading to challenges with viscosity and injection volumes. Conferences such as CPHi, PDA Universe of Pre-Filled Syringes, and PODD in 2024-2025 have highlighted innovations in drug delivery, including viscosity management technologies and faster absorption solutions. However, as drug volumes increase beyond 3 mL, new challenges arise for autoinjector usability and patient tolerance.

A key concern is balancing drug delivery with absorption in the subcutaneous cavity. If the delivery rate exceeds the absorption rate, drug accumulation may occur, potentially leading to discomfort or reduced efficacy. While autoinjectors are being tested for delivering up to 20 mL, their practicality is questionable due to injection time, tolerability, and usability factors.

The industry must consider whether large-volume autoinjectors align with patient needs or if on-body delivery systems (OBDS) are more suitable alternatives. Successful injection solutions require optimizing injection time, drug accumulation, and usability. If these factors cannot be balanced, regulatory approval may be difficult.

While formulation advancements may reduce injected volumes or enhance absorption, they won’t always maintain autoinjector compatibility. In some cases, splitting doses across multiple injections or utilizing OBDS devices might be a better alternative for effective and patient-friendly drug administration.