Abstract
BACKGROUND: Ease of injection is important to patients. An autoinjector was developed to deliver exenatide, a glucagon-like peptide-1 receptor agonist for type 2 diabetes mellitus. For autoinjection, 0.06-mm exenatide-containing microspheres are suspended in medium-chain triglycerides. Herein, we report design verification and usability testing of the autoinjector for exenatide once-weekly suspension (QWS) delivery. METHODS: Exenatide QWS in a single-chamber cartridge is self-injected subcutaneously with three main steps: mix, unlock, and inject. Design verification testing used validated testing methodology. A summative validation study with simulated-use scenarios evaluated unassisted performance on critical tasks (ease of use and the injection process). RESULTS: The autoinjector met specified design requirements for dose accuracy and torque/force. Of 104 participants enrolled (73 lay users, 16 health care professionals, and 15 pharmacists), 90 independently referred to instructions for use during testing. Users successfully achieved critical tasks on first attempt 87-100% of the time. Approximately 78% of participants successfully completed the full injection scenario, including 72% of lay users reporting visual or dexterity impairments. Initial use errors on critical tasks included not mixing well (n = 12), not removing needle cap (n = 8), and not holding needle to the skin for complete injection (n = 5). Untrained injection-naïve and trained injection-experienced lay users made the fewest errors (7% and 3%, respectively). Trained and untrained participants took 2:33 and 5:03 minutes, respectively, to complete a weekly injection. CONCLUSIONS: Users with a range of injection experience can rapidly learn to administer exenatide QWS autoinjector correctly, thus minimizing patient effort to manage their diabetes with injectable therapy.