This document provides an overview of buccal and sublingual drug delivery systems. It discusses the anatomy of the buccal mucosa and some of the advantages of buccal/sublingual routes, including avoidance of first-pass metabolism and protection from digestive enzymes. Various formulations are described, including tablets, patches, films, and semisolids. Evaluation methods like drug release studies, permeation studies, and bioadhesion tests are also summarized. The document provides a comprehensive introduction to buccal and sublingual drug delivery.