MECHANISMS, BARRIERS AND PATHWAYS OF ORAL MUCOSAL DRUG PERMEATION

This chapter focuses on reviewing the physicochemical evidence for the mechanism(s) of drug permeation across oral mucosa. It aims to identify those biological and physicochemical parameters which determine the rate and extent of human oral mucosal drug absorption. In addition, the potential barriers that a drug encounters and the possible pathways through which it may traverse the oral mucosa are reviewed. Information pertaining to the mechanism of oral mucosal drug absorption for a given drug, the barrier(s) that it is likely to encounter and the pathway by which it traverses the oral mucosa may (i) provide the rationale for drug candidate selection, analogue synthesis or prodrug design and (ii) provide an insight into methods by which membrane permeability can be modified. Each of these factors may facilitate the optimisation and rational development of drugs and delivery systems for buccal delivery.