Iontophoretic and Transdermal Drug Delivery Systems: Emerging Technologies and Applications

Iontophoretic and transdermal drug delivery systems have emerged as promising non-invasive alternatives to conventional oral and parenteral routes, offering controlled drug administration, improved patient compliance, and reduced systemic side effects. However, the highly efficient barrier function of the skin, particularly the stratum corneum, limits the passive permeation of most therapeutic agents, including hydrophilic drugs and biologics. Recent advancements in physical enhancement technologies, such as iontophoresis, microneedles, and ultrasound-mediated delivery, have significantly expanded the scope of transdermal drug delivery by transiently and reversibly modulating skin permeability. Among these approaches, iontophoresis enables precise, on-demand drug delivery through electrical driving forces, facilitating the transport of charged and polar molecules across the skin. This review highlights recent progress in iontophoretic and advanced transdermal systems, focusing on underlying mechanisms, formulation design strategies, analytical evaluation techniques, and emerging clinical applications. Special emphasis is placed on localized drug delivery and the potential role of iontophoresis in anticancer therapy. Current challenges and future perspectives related to clinical translation and regulatory considerations are also discussed, underscoring the growing significance of these technologies in modern drug delivery and precision therapeutics.