METHODS FOR ASSESSING THE BUCCAL MUCOSA AS A ROUTE OF DRUG-DELIVERY

This review focuses on the methods available for assessing the buccal mucosa as a portal for drug entry. It identifies the lack of informati on pertaining to the transport and barrier properties of this epitheli um as a major bottleneck in the optimisation of buccal drug delivery s ystems. The criteria for selecting an appropriate animal model for hum an buccal epithelium and a critical review of in vitro methodologies a re discussed. The harvesting of any mucosal samples should be by mecha nical means and the time between the moment of harvesting and the actu al start of the experiment should be minimised. Techniques available f or studying the barrier function of oral mucosa and its modulation by penetration enhancers are surveyed. In this respect three methodologic al approaches are discussed: (1) flux measurements, (2) histological a nd ultrastructural observations and (3) spectroscopic techniques. We c onclude that a combination of different methodological approaches, pre ferably in time-dependent studies, should be performed in order to obt ain a deeper insight into the buccal mucosa as a transport barrier and thereby aid the formulation of better strategies for overcoming it.