Mucoadhesive Buccal Film: An Emerging Platform for Controlled Drug Delivery Systems

Buccal drug delivery refers to the administration of medications through the buccal mucosa, the inner lining of the cheek. Owing to its relatively high permeability and rich vascular supply, the oral mucosa offers a unique and effective route for both local and systemic drug delivery. This route allows drugs to be absorbed directly into the systemic circulation while avoiding degradation in the gastrointestinal tract and hepatic first-pass metabolism. This review provides a functional foundation for buccal drug delivery by outlining the anatomical and physiological characteristics of the oral mucosa, the mechanisms governing drug permeation, and the experimental techniques used to evaluate buccal formulations. In addition, it examines the concept of mucoadhesion, including its advantages, limitations, and theoretical basis, and presents an overview of commonly employed mucoadhesive polymers, their methods of preparation, and the different categories of buccal drug-delivery systems. The development of advanced drug-delivery strategies, particularly mucoadhesive systems, has demonstrated significant potential to enhance therapeutic performance. By adhering firmly to the mucosal surface, the primary site of drug absorption, these systems allow controlled and localized drug release. This targeted delivery approach improves bioavailability while supporting both local therapeutic effects and systemic drug absorption. Mucoadhesion has been explained through several theoretical models, including electronic, adsorption, wetting, diffusion, fracture, and mechanical theories. Although numerous in vitro and in vivo techniques are available to study mucoadhesive behavior, the underlying mechanisms are still not fully understood. This review aims to consolidate current knowledge by discussing widely used mucoadhesive polymers, evaluation methodologies, and prevailing theories that describe mucoadhesion in pharmaceutical drug-delivery systems. The growing demand for patient-friendly dosage forms has further accelerated interest in innovative drug-delivery technologies that improve safety, convenience, and therapeutic efficacy. Among these, buccal films have emerged as a particularly attractive dosage form. Buccal films are thin, flexible, and easy to administer, making them more acceptable than conventional buccal systems such as tablets, gels, lozenges, wafers, or microparticles. In addition to bypassing first-pass metabolism, their strong mucoadhesive properties ensure prolonged residence at the site of application, leading to improved positional stability, enhanced comfort, and better patient compliance.