A Review on Current Advances in Transdermal Drug Delivery Systems

Transdermal drug delivery systems (TDDS) provide a non-invasive route for systemic medication administration, offering significant advantages over conventional oral and parenteral methods. These systems circumvent hepatic first-pass metabolism, improve drug bioavailability, and maintain steady-state plasma concentrations by delivering therapeutic agents through the skin, thereby enhancing therapeutic efficacy and reducing systemic side effects. The primary obstacle to this route is the highly impermeable stratum corneum, the outermost layer of the epidermis. Overcoming this barrier involves interactions between the drug's physicochemical properties, the formulation's design, and the skin's physiological state. Modern TDDS have evolved from simple passive patches to sophisticated platforms incorporating chemical permeation enhancers, vesicular nanocarriers like liposomes and transfersomes, and physical enhancement techniques such as microneedles and iontophoresis. These innovations have expanded the range of deliverable molecules from small, lipophilic compounds to larger biologics, including peptides and vaccines. The development and characterization of these systems rely on a robust framework of physicochemical, in vitro, and in vivo evaluation methods to ensure safety, stability, and predictable performance. The integration of smart materials and bioelectronics is paving the way for personalized, feedback-controlled therapeutic systems, can make TDDS a cornerstone of future medicine for managing a wide spectrum of acute and chronic diseases