Book excerpt: This volume provides a comprehensive overview of the current issues facing scientists working on delivering drugs locally and systemically via the membranes that line the mouth. The book describes the anatomical and physiological challenges of this route for drug delivery and how they impact the design of oral mucosal drug delivery systems. It also provides a detailed description of current oral mucosal drug delivery technologies that overcome these challenges alongside research, development and assessment methods. In 11 authoritative chapters, the book affords an in-depth evaluation of the major issues associated with this route of administration, namely the retention of the drug/product at the site of administration and increasing drug permeability through the oral mucosa. The book provides insights into the in vitro and in vivo methods available to assess drug permeability and retention, offers solutions on how to improve the permeation of the drugs through the oral mucosa, and explores approaches to prolong drug/product retention at the site of administration. It also indicates future directions in research and product development. Oral Mucosal Drug Delivery and Therapy is a key resource for those wishing to extend their knowledge of this field.