Novel cannula design improves large volume auto-injection rates for high viscosity solutions

Area of Science:

• Biomedical Engineering
• Drug Delivery Systems
• Pre-clinical Studies

Background:

• Large-volume autoinjectors (LVAI) require efficient syringe and cannula designs for subcutaneous (SC) drug delivery.
• Optimizing cannula dimensions is crucial for managing injection time and viscosity.

Purpose of the Study:

• To compare the injection performance of a novel ultra-thin wall (UTW) pre-filled syringe (PFS) cannula against a standard special thin wall (STW) PFS cannula in a 2 mL LVAI.
• To evaluate the feasibility of SC injection with varying injectate viscosities (2.3-30 cP) in swine models.

Main Methods:

• A prototype LVAI was used to test UTW and STW PFS cannulae in swine.
• Injection performance metrics included delivery time, volume, leakage, and tissue effects.
• Histological analysis was performed for UTW cannulae with viscosities up to 50 cP.

Main Results:

• Both UTW and STW cannulae achieved effective SC delivery up to 30 cP viscosity with minimal, transient tissue effects.
• The UTW cannula, featuring a larger lumen, demonstrated significantly faster delivery times compared to the STW cannula.
• Histological evaluation showed rare, minimal injection site reactions with UTW cannulae, even at 50 cP.

Conclusions:

• The study confirms the feasibility of LVAI SC injections using both UTW and STW PFS cannulae.
• The UTW cannula design shows potential for enabling more rapid LVAI injections, particularly for high-viscosity formulations, with acceptable tissue tolerance.