Transdermal Drug Delivery Systems: Progress, Obstacles, And Future Prospectives

Abstract

Transdermal patches offer a comfortable and non-invasive method for administering medication, marking a significant shift from traditional pills and injections. This review provides a detailed exploration of their core principles, from the structure of the skin and the variables influencing drug absorption to the various patch designs like matrix, reservoir, and drug-in-adhesive systems. It also assesses modern production methods, including solvent casting and hot-melt extrusion, weighing their practicality for large-scale manufacturing.

The discussion also covers key innovations designed to improve drug absorption, such as chemical agents (e.g., terpenes and fatty acids) and physical approaches like iontophoresis and microneedles. To ensure safety and efficacy, the text details essential testing protocols, from in vitro release and skin irritation studies to stability assessments that adhere to ICH standards. Furthermore, the real-world impact of this technology is illustrated with case studies of established transdermal products, including fentanyl for pain, oestradiol for hormone therapy, and patches for nicotine cessation.

The field continues to evolve dynamically, with emerging innovations like patches that deliver proteins, integrate glucose sensors, or use thermo-responsive smart polymers. Despite clear benefits such as avoiding first-pass metabolism and enhancing patient compliance, transdermal systems still face challenges like skin irritation and limitations on drug molecule size. Given that transdermal products now constitute 40% of investigational delivery systems and their market is expanding at a 25% CAGR, this review offers critical insights for the development of next-generation patches. The future of this progress lies in the integration of nanotechnology and novel biocompatible materials, which are set to unlock new therapeutic frontiers.