European Journal of Biomedical and Pharmaceutical Sciences

TRANSDERMAL DRUG DELIVERY SYSTEMS: A COMPREHENSIVE REVIEW

B. Premkumar*, D. Dhachinamoorthi, C. Santosh

ABSTRACT

Transdermal Drug Delivery Systems (TDDS) represent one of the most significant advances in non-invasive drug delivery technology, offering a reliable and patient-friendly alternative to oral and parenteral routes of administration. The skin, being the largest organ of the human body, serves as both a portal and a formidable barrier to drug permeation. A thorough understanding of the multilayered structure of human skin—particularly the stratum corneum and its lipid-bilayer organization—is fundamental to the rational design of effective transdermal formulations. This review comprehensively addresses the anatomy and physiology of skin and its associated barriers to drug permeation; the diverse categories of penetration enhancers including chemical, physical, and biochemical approaches; the classification, design principles, and mechanisms of various transdermal drug delivery systems; and the formulation strategies and in vitro/in vivo evaluation methodologies employed in transdermal product development. Emphasis is placed on clinically relevant drug candidates, polymer selection, adhesive systems, and modern analytical techniques used to characterize transdermal patches. The future potential of nanotechnology-based transdermal systems, microneedle arrays, and iontophoretic devices is also briefly addressed.

Keywords: Transdermal Drug Delivery, Skin Barrier, Stratum Corneum, Penetration Enhancers, Transdermal Patch, Iontophoresis, Microneedles, Flux, Permeability Coefficient, Controlled Release.