A method for evaluating drug penetration and absorption through isolated buccal mucosa with highly accuracy and reproducibility.

The purpose of the project is to establish a standardized operation method of the in vitro permeability model to maximize mucosal integrity and viability. The model drug lidocaine permeability, 20 kDa fluorescein isothiocyanate-dextran, H&E staining, and mucosal viability were used as evaluation indicators. Firstly, the buccal mucosae of rats, rabbits, dogs, porcine, and humans were analyzed by H&E staining and morphometric analysis to compare the differences. Then, we studied a series of operation methods of isolated mucosa. The buccal mucosae were found to retain their integrity in Kreb's bicarbonate ringer solution at 4 °C for 36 h. Under the long-term storage method with program cooling, freezing at -80 °C, thawing at 37 °C, and using cryoprotectants of 20% glycerol and 20% trehalose, mucosal integrity and biological viability can be maintained for 21 days. The heat separation method was used to prepare a permeability model with a mucosal thickness of 500 μm, which was considered to be the optimal operation. In summary, this study provided an experimental basis for the selection and operation of in vitro penetration models, standardized the research process of isolated mucosa, and improved the accuracy of permeability studies.