A REVIEW ON TRANSDERMAL DRUG DELIVERY THROUGH PATCHES

Transdermal drug delivery systems (TDDS) have emerged as an effective alternative to conventional oral and parenteral routes, offering controlled and sustained release of therapeutics through the skin. Transdermal patches bypass first-pass metabolism, improve patient compliance, reduce dosing frequency, and maintain steady plasma drug concentrations. This review highlights the fundamental principles of transdermal drug delivery, including skin structure, mechanisms of permeation, and factors influencing transdermal transport such as drug physicochemical properties and formulation strategies. Various types of transdermal patches—reservoir, matrix, drug-in-adhesive, micro-needle-assisted, and iontophoretic systems—are discussed with emphasis on their design, advantages, limitations, and clinical applications. Recent advancements in penetration enhancers, nanocarrier- based patches, and smart transdermal systems are also explored, demonstrating significant potential for improving therapeutic outcomes. Overall, TDDS represent a promising platform for non-invasive drug administration, and continued research may further expand their applicability to a broader range of drugs, including macromolecules and biologics.