Evaluation of multi-port needles for enhanced intramuscular drug delivery via experimental and CFD models

Intra-muscular (IM) injection via hypodermic needle and syringe is the most common delivery method of vaccines due to the muscle tissue ability to receive large volumes, high degree of vascularization, and tolerance of needle insertion. When injections are augmented with enabling technologies such as electroporation (EP), the drug dispersion zone becomes an important consideration since it should match with the electric field generated by the EP device. Herein, we sought to modify the flow from a standard hypodermic by implementing multiple side-ports along the length of the needle. We evaluated the flow in these side-port designs using CFD simulations and experimental validation. Our results indicate that low flow rates ( $Q<10mL/min,Re=4\rho Q/\pi d\mu \lesssim 500)$ result in non-uniform flow distribution, while higher flow rates $(Q\gtrsim 15mL/min,Re\gtrsim 769)$ result in near-uniform distribution of flow along all the side-ports, potentially creating superior drug dispersion pattern along the needle length for improved cellular uptake with EP.