(682g) Computational Fluid Dynamics Modeling and Experimental Studies of Multi-Port Needles for Optimization of Drug Delivery to Multiple Tissue Layers

Transdermal injections remain the most efficient way of delivering drugs to the circulatory system to circumvent the barriers typically associated with enteral routes. However, the therapeutic or immunologic response can be limited due to various factors: (a) poor drug diffusion, (b) inaccurate deposition/location of drug, or (c) the need for electroporation to enhance cellular uptake. New developments in drug formulation have presented the industry with successful protein, RNA, and DNA based vaccines; those, however, suffer with poor efficacy in part due to the difficulties of properly delivering these macro-molecules at high concentration, which can result in high-viscosity injectables.

Whilst the hypodermic needle remains the vanguard method of delivery, we sought to improve the delivery with a modified flow regime by placing the outlets along the length of the needle, to create a so-called “sprinkler needle” effect. With the aid of CFD based simulations, we created 3D models of 22 gauge hypodermic needles modified with side-ports along the length of its body. Geometry, size and number were the proposed variables attributed to the side-ports with the goal of achieving a tailored flow distribution along the length of the needle. In this first phase of our study, the number of side-ports was our main focus; fluid viscosity was also a key variable in our models. Utilizing both simulations and experiments, we were able to study numerous high-viscosity injections and determine the volumetric flow rates through each port and ultimately design geometries to achieve a given flow distribution.