Precise Intradermal Drug Delivery Mediated by the Elastic Membrane in the Needle-Free Injection

Needle-free drug delivery systems present a promising alternative to traditional needle-based injections, providing safety and patient compliance. This study developed an elastic-membrane-mediated needle-free injection (NFI) for precise intradermal drug delivery by placing a layer of elastic membrane on the surface of the injection target. This method was studied using the hydrogel model and porcine skin. In the hydrogel experiment, high-speed photography captured the hydrodynamic characteristics of the injection process with and without the elastic membranes (polydimethylsiloxane membrane and polyethylene membrane). We found that the presence of the membrane effectively modulated the drug distribution within the hydrogel; for instance, a 60% reduction in penetration depth and a 90% increment in horizontal diffusion were witnessed when a 49 μm polyethylene membrane was deployed. Experiments on porcine skin involved the injection of aqueous and oil-based solutions, representing a broad spectrum of drug formulations utilized in human and veterinary medicine. Compared with conventional NFI, membrane-mediated NFI effectively reduced the injection depth (50% for aqueous solution and 40% for oil-based solution) and enhanced the horizontal diffusion (44% for aqueous solution and 8.1% for oil-based solution), resulting in more drugs delivered into the dermis layer. We conclude that elastic-membrane-assisted NFI offers a simple, speedy, and effective strategy for intradermal drug delivery, potentially enhancing the efficacy in vaccination.