Smart Polymer-Based Transdermal Film-Forming Sprays: Stimuli-Responsive Drug Delivery Systems

Transdermal drug delivery systems (TDDS) have emerged as a promising alternative to conventional oral and injectable dosage forms due to their ability to improve patient compliance, avoid first-pass metabolism, and maintain sustained plasma drug concentrations. Among the advanced transdermal approaches, film-forming sprays (FFS) have gained considerable attention because of their non-invasive nature, ease of administration, rapid drying, and enhanced cosmetic acceptability. Recent progress in polymer science has enabled the development of smart or stimuli-responsive polymers capable of responding to environmental triggers such as temperature, pH, enzymes, light, and electrical stimuli. Integration of these intelligent polymers into transdermal film-forming sprays has resulted in advanced drug delivery platforms with controlled and site-specific drug release profiles. Smart polymer-based FFS exhibit improved therapeutic efficacy, reduced dosing frequency, enhanced drug permeation, and minimized systemic adverse effects. This review discusses the fundamentals of transdermal film-forming sprays, classifications of stimuli-responsive polymers, mechanisms of smart drug release, formulation strategies, evaluation techniques, therapeutic applications, recent advancements, and future perspectives. Particular emphasis is placed on thermoresponsive and pH-responsive polymeric systems owing to their growing pharmaceutical importance. The review highlights the potential of intelligent film-forming sprays as next-generation transdermal therapeutics for personalized medicine and targeted drug delivery.