The document outlines the buccal drug delivery system (BDDS), highlighting its mechanism of drug delivery through the buccal mucosa. It details the types of dosage forms used, the formulation components such as mucoadhesive polymers and permeation enhancers, and their respective roles in enhancing drug absorption. Additionally, it discusses various formulation types including tablets, patches, gels, and sprays, along with their preparation methods and applications.