The effects of permeation enhancers on the surface morphology of the rat nasal mucosa: a scanning electron microscopy study.

A rat model has been developed to compare relative morphological changes in the nasal mucosa after exposure to potential membrane permeation enhancers. Scanning electron microscopy was used to characterize gross structural and specific cellular changes following exposure. Micrographs of the rat nasal mucosa were scored in four categories: (1) mucosal surface integrity, (2) ciliary morphology, (3) mucus/extracellular debris, and (4) presence of red blood cells. The order of increasing morphological damage resulting from a 5-min exposure to each surfactant was 0.5% Solulan C-24 congruent to 0.5% Solulan C-24/0.5% sodium tauro-24,25-dihydrofusidate (STDHF) less than 0.5% STDHF less than 1.0% STDHF much less than 1.0% Laureth-9 less than 1.0% sodium taurodeoxycholate congruent to 1.0% sodium deoxycholate. The changes observed in the mucosal morphology after exposure to the various surfactants are in general agreement with data in the literature. This model is able to compare rapidly the relative morphological effects on the mucosal membrane of different nasal formulations.