Anatomy and Physiology of the Oral Mucosa

Abstract

The oral route of drug delivery Drug delivery remains the preferred method for the administration of medicinal compounds to humans due to convenience, cost, and ease of drug administration, which, not unexpectedly, leads to an increase in patient compliance. However, for conventional low molecular weight organic and peptide-based therapeutic compounds that are subject to either a high “first-pass” effect due to intestinal and/or hepatic extraction or extensive degradation and/or inactivation by gastric acid or gastrointestinal enzymes Enzymes gastrointestinal , and for patients that would otherwise not be administered a drug by the oral route due to either a specific disease state (malabsorption syndrome, immediately postabdominal surgery, etc.) or age (pediatric or geriatric), the oral transmucosal route of drug administration is a viable and safe alternative. This has led to the development of a variety of dosage forms, for example, mucoadhesive tablets, gels, patches, ointments, and films Films to name a few, for placement and subsequent delivery of various drug substances from the oral cavity. This chapter reviews the most pertinent concepts regarding the anatomy Anatomy and physiology Physiology of the oral mucosa and its relevance to local and systemic oral transmucosal drug delivery Transmucosal drug delivery . Some of the concepts addressed involve the advantages Advantages and disadvantages Disadvantages of oral transmucosal drug delivery Drug delivery transmucosal , routes of drug delivery, factors that influence drug delivery which are associated with the permeant and the microenvironment within the oral cavity (e.g., mucus, saliva, and salivary glands) Salivary gland , and practical considerations regarding tissue irritation Tissue irritation and/or damage when using this route of drug administration. Lastly, the role of permeation enhancers and buffering agents/pH modifiers in oral transmucosal drug delivery are discussed. It is hoped that the fundamental information contained in this chapter regarding the anatomy and physiology of the oral cavity will assist those pharmaceutical scientists directly involved with the formulation of dosage forms intended for oral transmucosal drug delivery.