Transdermal Patches: Comprehensive Review of Drug Delivery Innovation and Clinical Applications

Transdermal drug delivery systems (TDDS) represent a paradigm shift in pharmaceutical administration, offering non-invasive therapeutic delivery through the skin. This comprehensive review examines the fundamental mechanisms underlying transdermal permeation, including passive diffusion through the stratum corneum, drug partitioning, and molecular transport pathways12. The anatomical and physiological properties of skin, including the brick-and-mortar structure of corneocytes and lipid matrices, establish the foundational understanding for overcoming the skin barrier. Contemporary formulation strategies encompassing polymer matrices, plasticizers, and chemical penetration enhancers have enabled successful delivery of diverse therapeutic agents. Advanced technologies including microneedles, iontophoresis, electroporation, and sonophoresis are expanding the scope of drugs amenable to transdermal administration. Clinical applications span pain management with fentanyl patches, hormone replacement therapy with estrogen and testosterone formulations, cardiovascular management with nitroglycerin delivery, and neurological applications including scopolamine and selegiline patches. This article synthesizes findings from over 20 peer-reviewed research publications to provide pharmaceutical scientists with comprehensive knowledge of transdermal patch development, evaluation, regulatory requirements, and emerging therapeutic opportunities.