Characterization Methods for Oral Mucosal Drug Delivery

Abstract

Drug delivery across oral mucosal membranes has emerged as an excellent alternative for compounds that cannot be delivered orally. However, a standardized method to evaluate drug absorption across oral mucosal membranes, either in vitro or in vivo, still remains elusive. This chapter provides a comprehensive review of the current in vitro and in vivo methodologies employed in the literature for evaluating oral transmucosal absorption of compounds. The barrier function of oral mucosa along with the transport mechanisms is briefly reviewed. The methods to study drug absorption in vivo such as the buccal absorption test along with its refinements are discussed. In addition, a brief review of the present knowledge relating to various in vitro methods including the selection of suitable animal species, apparatus, and their limitations is given. Methods to test residence time, mucoadhesion, and drug release are also discussed in this chapter, together with a special emphasis on the use of buccal cell cultures as a means to study oral mucosal drug absorption. The need to conduct pharmacokinetic (PK) studies is also highlighted and discussed in the chapter.