Modeling the oral cavity: in vitro and in vivo evaluations of buccal drug delivery systems.

The delivery of drugs through the buccal mucosa has attracted much research interest over the past two decades and numerous approaches, both conventional and complex, have been developed in an attempt to deliver a variety of pharmaceutical compounds via the buccal route. However, the design of appropriate in vitro and in vivo methods to evaluate the behavior of these delivery systems is often ignored. This review aims to outline the progress in the in vitro and in vivo modeling of buccal drug delivery and provide a critical review of currently used methods. The development of a range of in vitro methods is outlined including disintegration/dissolution testing, in vitro mucoadhesion tests, in vitro residence time evaluation and permeability studies. The suitability of commonly used animal models for in vivo evaluation is also discussed and the physiological comparison of the animal oral cavity with that of a human's is described.