Purpose: Evaluation of product viscosity, density and aeration on the dose delivery and accuracy for intravitreal injections with commonly used commercially available hypodermic 1 mL syringes.
Methods: Six commercially available hypodermic 1 mL syringes with different specifications were used for the study. Syringes were filled with the test solutions with different densities and viscosities. Syringes were also subjected to shaking stress to introduce aeration in the test solutions in the presence of different surfactant concentrations with and without high antibody concentration. Target intravitreal volumes of 100 μL, 50 μL and 30 μL were tested to assess dosing accuracy in a controlled simulated administration setup using DIN ISO 11040-4 guidelines and Zwick/Roell Z010 TN instrument.
Results: With increasing product viscosity, higher volumes and hence doses were delivered especially for very low volumes like 50 μL and 30 μL. No impact of increasing product density was found on the delivered dose. The presence of surfactants or high protein concentration can lead to aeration, which also negatively affects the dose accuracy and precision.
Conclusion: Formulation parameters like viscosity can have an impact on dose delivery using hypodermic syringes for intravitreal injections and on the resulting glide force.
Keywords: dose accuracy; formulation; intravitreal injections; surfactant; viscosity.