[Oral mucosal administration]

Oral mucosal administration (OMA) can circumvent hepatic first-pass metabolism and avoid gastrointestinal degradation while offering advantages, such as a rapid onset of action, noninvasiveness, and convenience, positioning it as an important complementary and alternative route to conventional oral and parenteral administration. How-ever, the dynamic and moist environment of the oral cavity leads to inadequate formulation adhesion, substantial drug permeation barriers across the mucosa, and suboptimal controlled-release precision. These limitations have driven the development of oral mucosal drug delivery systems (OMDDSs). This paper systematically summarizes the structural and physiological characteristics of the oral mucosa and dissects the core advantages and major challenges of OMA. It further comments on the research progress and application status of various OMDDSs, including tablets, nanoparticles, hydrogels, patches/films, and microneedles, as well as their clinical application in the management of local oral diseases and systemic disorders. Finally, it discusses future directions, such as artificial intelligence-assisted design, breakthroughs in macromolecular delivery, standardized evaluation systems, and theranostic integration, to provide theoretical references and innovative insights for the rational design and clinical translation of novel OMDDSs.