Buccal Tissues and Cell Culture

Abstract

The buccal mucosa may be an alternative route of administration for selected compounds that cannot be delivered using conventional oral dosage forms, because they undergo either extensive first-pass metabolism or degradation in the gastrointestinal tract. The buccal route has several advantages for long-term controlled drug delivery. The oral mucosa is readily accessible for placement and removal of a delivery device, is well supplied with both vascular and lymphatic drainage, and avoids both hepatic first-pass metabolism and presystemic metabolism in the gastrointestinal tract. Additionally, the buccal mucosa is considerably more permeable than the skin, an accepted route for controlled drug delivery, and thus this alternative route would expand the number of compounds that could be delivered in therapeutic doses. Furthermore, the time lag through buccal mucosa is considerably shorter than that seen though skin. Unidirectional delivery of the drug to the mucosa from a device with an impermeable backing reduces drug loss due to swallowing. The development of a small, thin flexible device that causes minimal disruption to normal activities such as eating, drinking, and talking is the ultimate aim of this area of drug delivery research. As part of developing such a delivery system, the degree of drug permeation through the buccal mucosa must be determined. Initial in vitro studies to measure steady-state drug flux and time lag and to evaluate different delivery systems can be performed in modified Ussing chambers using buccal mucosa isolated from an animal model. Permeation, metabolism, and toxicity can be assessed in vitro using a recently developed buccal cell culture system that allows the generation of multiple cultures from a small amount of starting tissue.