Innovative Approaches for Topical and Transdermal Drug and Cosmeceutical Delivery.

In recent years, non-invasive drug delivery methods have emerged as promising alternatives to conventional needle-based injections, with Transdermal Drug Delivery Systems (TDDS) gaining particular attention due to their reduced patient rejection rates, improved compliance, and ease of application. Beyond pharmaceuticals, TDDS is expanding its role in skincare and cosmetic formulations, enabling localized delivery while minimizing systemic exposure and off-target effects. Despite the advantages, the skin's complex physicochemical barrier properties continue to present major challenges for effective penetration. To address these limitations, nanotechnologybased strategies such as liposomes, niosomes, ethosomes, solid lipid nanoparticles, and polymeric nanocarriers have been widely investigated. These nanosystems enhance solubility, stability, and controlled release while improving dermal penetration and bioavailability. Encapsulation technologies, including nanoemulsions, nanogels, and biodegradable polymeric systems, provide protection of labile cosmetic actives, sustained delivery, and targeted action within specific skin layers. The chapter further highlights recent advancements in chemical penetration enhancers, biopolymers, and hybrid delivery vehicles such as gels, films, and emulsions designed to optimize cosmetic performance. With scientific progress, translating nanotechnology-driven TDDS into cosmetic applications requires careful consideration of regulatory frameworks, particularly for safety assessment, nanotoxicology, product labeling, and compliance with international guidelines (e.g., FDA, EMA, and EU Cosmetic Regulation). These aspects are critical for consumer safety, ethical marketing, and global acceptance of nanocosmeceuticals. This review provides an updated overview of topical and transdermal cosmetic formulations, emphasizing how nanotechnology and encapsulation strategies are redefining product efficacy and safety, while outlining the regulatory challenges that shape their future commercialization.