Drug Absorption Through The Oral Mucosa

As a familiar drug delivery route, buccal mucosa as an alternative site for the delivery of drugs into the systemic circulation has recently received much attention. There are many reasons why the buccal mucosa might be an attractive site for the delivery of drugs, excellent accessibility, high patient acceptance and compliance, low enzyme activity and avoiding first-pass effect, etc.The porcine buccal mucosa was used for in vitro study because the permeability of this membrane is very similar to the human buccal tissue. In addition, to investigate the permeabilities of drugs, the alcohols, carboxylic acids, phenols, benzoic acid, caffein and hydrocortisone were selected as the model drugs for the thorough study of their properties. Besides, the permeabilities of 19 drugs vias buccal mucosa and human skin were compared.This study exerted TK-12A diffusion instrument, in which the donor chamber was filled with saturated solutions of drugs so as to keep changeless concentrations. The results revealed that the process of permeability vias buccal mucosa and human skin were similar. There was a linear relation between Q and t, which accorded with Fick's diffusion equation.The results indicated that the permeabilities of 19 drugs vias buccal mucosa were larger than that of human skin. However, different kinds of drugs differed in the characteristic of permeability. For instance, to benzoic acid, caffein and hydrocortisone, the permeabilities vias buccal mucosa were 3, 50, 1000 times larger than that of human skin, respectively. The results implied that most drugs held stronger permeabilities vias buccal mucosa than human skin, which makes great sense to the application of drug design.Moreover, the three-layer BP neural network model which took the logK and MV as the prediction parameters was obtained . The values of the predicted logP and the observed logP were coincident. It denoted that the permeability coefficients (P) of drugs through buccal mucosa were well correlated with their oil-water partition coefficients (K) and molecular volumes (MV). However, the regression equation of the permeability coefficients of drugs through buccal mucosa obtained revealed that the pertinence of the equation was not as good as the neural network model. Hence, it could be concluded that the permeability coefficients (P) of drugs through buccal mucosa were mainly rest with their oil-water partition coefficients and molecular volumes, but the relation was complicatedly nonlinear.