Impact of Monomer Selection and Behavior on Transdermal Drug Delivery Systems: Regulatory and Formulation Perspectives

This review article provides a comprehensive overview of the main monomers used in transdermal drug delivery systems (TDDS), such as acrylates, methacrylates, polyethylene glycol acrylates, crosslinking monomers, and specialty monomers. It examines their impact on key quality attributes (critical quality attributes), including drug release kinetics, adhesion-cohesion balance, mechanical strength, and stability under thermal and humidity stress. The article also summarizes Food and Drug Administration and European Medicines Agency requirements for monomer characterization in regulatory submissions, details analytical techniques for measuring residual monomers and analyzing the resulting polymers, and highlights recent developments in the regulatory landscape. Monomer selection is emphasized as a vital scientific and regulatory factor that influences TDDS quality, performance, and patient safety.